LX470 AHC issues - pressure sensor 1998 Vs. 2002 (1 Viewer)

[suprarx7nut]

SupraRX7


I was just about to reply to you and INDOCRUISW with the update later today, but since you were so kind to check in with me, I will do it now. You and INDOCRUISE are correct about this simple gear pump. It is a VERY simple concept and should work if there is fluid in it- I'm a Mechanical Engineer,, so i get that! .
The description below is with the replacement pump that has never been used, but I DID OPEN IT UP ( STUPID !) I have another new pump (AHC Pump sub-assembly 48901-60010) on order from IMPEX and i hope it will arrive by Friday. Until then, I want to see if this new pump that i have can work again.

I did as you described, and just filled the pump assy with oil, BEFORE attaching the reservoir so I could "burp" the pump housing by holding it at an angle where you can see that opening in the top of the AL pump housing that the tank grommet fits into. ( BTW- I bought a NEW grommet for that interface between the reservoir and AL pump housing. ) I watched the bubbles rise as I filled the pump through the 1" wide opening. When the fluid was no longer going into the pump gear area and was filled to the top of that opening, I applied 12 V directly to the pump and no fluid stream emerged when I removed the rubber stopper from the outlet ( I ll attache pictures when I go back to the garage to take them in about an hour) THIS..... IS A PROBLEM .. all i can figure out is it means ... there is still air INSIDE the gear pump housing as it is NOT sealing inside it. There is no pressure resistance to since the outlet is open to the atmosphere, but it should still send out a stream of oil like it did before I removed it from the LX and disassembled it to check the inlet and outlet tiny screens!!! NOW,..... I wish i would have NEVER done that .....

I will try again later this morning and attach pictures of what I just described above. I wish we could attach video, but the forum says i have to have a .PNG or .GIF file, not a .MOV file so i cannot! I do appreciate all Ya'll help with this, YOU, INDOCRUSIE, 2001LC, MORIDINLG, and everyone who has contributed to this post. This is a wonderful gift and tool to help all of us, on a personal level. THANK YOU!

My instinct tells me your disassembly of the pump isn't/wasn't the issue. You didn't let any magic out of it when you opened it up, haha.

To clarify in painful detail: You have the pump with the reservoir totally removed so that all you see is this (ignore red arrows, not my pic):

And you fill that inlet column where the grommet goes from the reservoir (but the reservoir is NOT present) with oil.

Then you turn on the pump. Again, the reservoir is in a separate room, far away from this situation.

And the column of oil stays there? No fluid movement? It doesn't drain out at all?

 

[IndroCruise]

SupraRX7


I was just about to reply to you and INDOCRUISW with the update later today, but since you were so kind to check in with me, I will do it now. You and INDOCRUISE are correct about this simple gear pump. It is a VERY simple concept and should work if there is fluid in it- I'm a Mechanical Engineer,, so i get that! .
The description below is with the replacement pump that has never been used, but I DID OPEN IT UP ( STUPID !) I have another new pump (AHC Pump sub-assembly 48901-60010) on order from IMPEX and i hope it will arrive by Friday. Until then, I want to see if this new pump that i have can work again.

I did as you described, and just filled the pump assy with oil, BEFORE attaching the reservoir so I could "burp" the pump housing by holding it at an angle where you can see that opening in the top of the AL pump housing that the tank grommet fits into. ( BTW- I bought a NEW grommet for that interface between the reservoir and AL pump housing. ) I watched the bubbles rise as I filled the pump through the 1" wide opening. When the fluid was no longer going into the pump gear area and was filled to the top of that opening, I applied 12 V directly to the pump and no fluid stream emerged when I removed the rubber stopper from the outlet ( I ll attache pictures when I go back to the garage to take them in about an hour) THIS..... IS A PROBLEM .. all i can figure out is it means ... there is still air INSIDE the gear pump housing as it is NOT sealing inside it. There is no pressure resistance to since the outlet is open to the atmosphere, but it should still send out a stream of oil like it did before I removed it from the LX and disassembled it to check the inlet and outlet tiny screens!!! NOW,..... I wish i would have NEVER done that .....

I will try again later this morning and attach pictures of what I just described above. I wish we could attach video, but the forum says i have to have a .PNG or .GIF file, not a .MOV file so i cannot! I do appreciate all Ya'll help with this, YOU, INDOCRUSIE, 2001LC, MORIDINLG, and everyone who has contributed to this post. This is a wonderful gift and tool to help all of us, on a personal level. THANK YOU!

Just to be clear ....

It is worth pursuing air inside the AHC Pump sub-assembly 48901-60010 -- but that is not the cause in my opinion.

My previous Post #98 (now edited for emphasis) means to say that "... the cause of lack of discharge from the AHC Pump in the subject vehicle is due to the dis-assembly and re-assembly of the AHC Pump sub-assembly with the top-plate insufficiently tightened – resulting in loss of Discharge pressure and flow due to internal FLUID leaks at the seals".

In other words, fluid is escaping past the seals and out of the AHC Pump sub-assembly 48901-60010 into the enclosure provided by the outer case.

It is most likely that the fluid is escaping past the O-rings at the gearcases OR possibly past the triangular O-ring OR possibly past the small O-ring at the Discharge.

Such leakage will not be visible because the Pump sub-assembly is enclosed in the overall assembly.

This is similar to the issue described previously by @BullElk.

Problems with seals are not uncommon with gear pumps (not restricted to AHC Pumps) and DO result in the situation described -- low flow or no flow and so poor or no pressure -- and of course a gear pump only develops pressure when there is resistance to flow.

In this case it MAY be possible to fix the problem simply by tightening the two bolts holding together the parts of the AHC Pump sub-assembly 48901-60010 and the two bolts attaching it to the main assembly.

Or it may be that the O-rings at the gearcases simply are not correctly seated.

The descriptions, especially the description in Post #100, do not fit "air" inside the AHC Pump sub-assembly.

 

[suprasvobodea]

My instinct tells me your disassembly of the pump isn't/wasn't the issue. You didn't let any magic out of it when you opened it up, haha.

To clarify in painful detail: You have the pump with the reservoir totally removed so that all you see is this (ignore red arrows, not my pic):
View attachment 3652479

And you fill that inlet column where the grommet goes from the reservoir (but the reservoir is NOT present) with oil.

Then you turn on the pump. Again, the reservoir is in a separate room, far away from this situation.

And the column of oil stays there? No fluid movement? It doesn't drain out at all? YES. THIS IS WHAT I HAVE. I put oil in this opening to the pump , untill it was full, applied 12V to the pump, and it did not get sucked down and shot out the outlet. IT just leaked out when i removed the rubber plug

I answered in BLUE

Just to be clear ....

It is worth pursuing air inside the AHC Pump sub-assembly 48901-60010 -- but that is not the cause in my opinion.

My previous Post #98 (now edited for emphasis) means to say that "... the cause of lack of discharge from the AHC Pump in the subject vehicle is due to the dis-assembly and re-assembly of the AHC Pump sub-assembly with the top-plate insufficiently tightened – resulting in loss of Discharge pressure and flow due to internal FLUID leaks at the seals".

In other words, fluid is escaping past the seals and out of the AHC Pump sub-assembly 48901-60010 into the enclosure provided by the outer case.

It is most likely that the fluid is escaping past the O-rings at the gearcases OR possibly past the triangular O-ring OR possibly past the small O-ring at the Discharge.

Such leakage will not be visible because the Pump sub-assembly is enclosed in the overall assembly.

This is similar to the issue described previously by @BullElk.

Problems with seals are not uncommon with gear pumps (not restricted to AHC Pumps) and DO result in the situation described -- low flow or no flow and so poor or no pressure -- and of course a gear pump only develops pressure when there is resistance to flow.

In this case it MAY be possible to fix the problem simply by tightening the two bolts holding together the parts of the AHC Pump sub-assembly 48901-60010 and the two bolts attaching it to the main assembly.

Or it may be that the O-rings at the gearcases simply are not correctly seated.

The descriptions, especially the description in Post #100, do not fit "air" inside the AHC Pump sub-assembly.

As SupraRx7 suggested I just filled the pump assy with oil, BEFORE attaching the reservoir so I could "burp" the pump housing by holding it at an angle where you can see that opening in the top of the AL. pump housing that the tank grommet fits into. ( BTW- I bought a NEW grommet for that interface between the reservoir and AL pump housing. ) I watched the bubbles rise as I filled the pump through the 1" wide opening. When the fluid was no longer going into the pump gear area and was filled to the top of that opening, I applied 12 V directly to the pump and no fluid stream emerged when I removed the rubber stopper from the outlet ( I ll attache pictures when I go back to the garage to take them in about an hour) THIS..... IS A PROBLEM .. all i can figure out is it means ... there is still air INSIDE the gear pump housing as it is NOT sealing inside it. There is no pressure resistance to since the outlet is open to the atmosphere, but it should still send out a stream of oil like it did before I removed it from the LX and disassembled it to check the inlet and outlet tiny screens!!! NOW,..... I wish i would have NEVER done that .....

Well , I topped off the opening where the reservoir attaches and applied 12 V to the motor and got NOTHING! No fluid movement from the little pool in that opening . S I wish we could attach a video, but the forum says I have to have a . PNG or. GIF file, not a . MOV file so I cannot! I do appreciate all Ya'll help with this, YOU, INDOCRUSIE, 2001LC, MORIDINLG, and everyone who has contributed to this post. This is a wonderful gift and tool to help all of us, on a personal level. THANK YOU!

I just applied 12V to this and NOTHING changed in the fluid level!! What is wrong here ..?? Why won't the gears move the oil to the outlet? When I remove that rubber stopper, it just leaks out - when the pump IS RUNNING!

 

[suprasvobodea]

@suprasvobodea -- you certainly have had more than a fair share of frustrations!! Hopefully a fix soon emerges.

The above Posts from @suprarx7nut and @Moridinbg contain excellent leads based on their deep knowledge and experience -- it is always worth following these guys ….

To add a bit more, a ‘long check list’ has been created in this very long Post. It may be TLDR – apologies offered, past mid0night on the East Coast of Australia, too late to try to reduce the length.

The limitation of trying to provide assistance on a Forum such as this is that the vehicle cannot be seen nor heard nor felt by ‘advisors’ on IH8MUD and coordinating phone calls across international time zones is too difficult -- and so misunderstandings and wrong conclusions are all too easy!

The ideas below are meant to provide @suprasvobodea with information along with some comments -- a range of items to be considered -- a ‘check-list’. @suprasvobodea will know what has been done and what merits further attention in the list below and what is not worth further effort.

Actual Part Numbers checked at the Partsouq website have been used to identify component parts and avoid confusion where different people may use slightly different words (for example, between different seals and O-rings). Partsouq or other sites or Google search can be used to quickly find pictures of relevant components ….

Let’s start at the beginning ….

If previous Posts have been understood correctly, the following AHC components have been replaced with new OEM parts by @suprasvobodea:

-- all four ‘globes’,​

-- all four ‘shock absorbers’,​

-- Height Control Accumulator,​

-- Pressure Sensor (twice),​

-- AHC Pump sub-assembly inclusive of seals and O-rings (not gearcase O-rings),​

-- AHC Fluid.​

There are suspicions about the solenoid valve at the Height Control Accumulator. However, the Height Control Accumulator is NOT vital for bleeding nor for raising the vehicle. The AHC Pump can and will do this, just more slowly, provided that the AHC Pump sub-assembly is able to work correctly.

@suprasvobodea advises that all Height Control Sensors have been opened, inspected and tested electrically per FSM.

The Damping Force Control Actuators, the Control Valve Assembly and the ECU have not been reviewed.

It is unclear how much harness and circuit review has been done and whether or not damaged wiring is a contributor to DTC C1762 on this vehicle.

It is assumed that all AHC-related tests were conducted with wheels on the ground, all doors and rear hatch closed (and no faults in door-light circuit), foot-off-brake (and no faults in brake-light circuit), steering straight ahead, etc, etc (all of which cause AHC conflicts), plus engine started (not just ignition switched “on”).

The vehicle is stuck at LO height (or maybe on the bump stops?), will not raise, and persistently presents Diagnostic Trouble Code (DTC) C1762 with the FSM-specified response time of 0.6 seconds. This DTC C1762 returns almost immediately (0.6 seconds) after it has been cleared by Techstream or manually when the vehicle is re-started.

This means that the AHC/TEMS system is following its settings to protect itself from further damage (and maybe Toyota/Lexus would say protecting the Driver and Passengers from misadventure).

In the case of DTC C1762, as specified in the FSM, the ECU puts the vehicle into “fail safe function” and causes the vehicle to default to the lowest AHC height at any wheel (in this case LO height is reported) and also to default to Step 8 (mid-range of the 16 steps of the damping settings available in TEMS).

No other DTC’s have been reported. (They may exist -- but the quick-acting DTC C1762 may be responding first, masking other fault conditions yet to be revealed).

In this DTC C1762 “fail safe function” condition, the vehicle cannot be raised, nor can there be any continuous auto self-levelling in real time -- which is the basic Active Height Control (AHC) purpose. Nor can there be any continuous real time adjustment across the 16 damping steps, responding to road conditions in real time -- which is the basic purpose of the Toyota Electronic Modulated Suspension (TEMS).

The vehicle will remain in this condition until the cause of DTC C1762 is found and resolved.

The “Active Test” whose full name is the “Height Control Operation Test” cannot be used while DTC C1762 prevails. It is not designed to be used to by-pass the hydraulic protection provided by DTC C1762 or other protective DTC’s. That is not its purpose. To do so would be the hydraulic circuit equivalent of by-passing a burnt-out fuse in an electrical circuit with a nail. We could wish that the designers made different arrangements when the TEMS system was devised and used on the Toyota Soarer in 1983 and later adapted for use in Lexus LX470 in 1998 and onwards and also as an option on some LC100 models. The Toyota/Lexus designers have not changed the design for 100 series – there are differences in the evolution on 200 series and 300 series.

The cause of DTC C1762 on this vehicle remains elusive.

Air in the AHC system seems an extremely likely cause of DTC C1762 on this vehicle given the hydraulic circuit disruptions required for the component change-outs.

Along the way a fault with the AHC Pump has emerged. This is preventing the cause of DTC C1762 from being confirmed and preventing the vehicle from being raised and lowered as part of a normal bleeding process.

Even when connected directly to a 12 volt DC source, weak low pressure Discharge is observed from the overall AHC Pump assembly (the whole thing -- Part Number 48910-60012) on open circuit with Discharge pipe detached. This is described by @suprasvobodea as a dribble from the open Discharge which can be stopped with a finger, even while the AHC Motor and AHC Pump continue to run.

Clearly, AHC Pump does not develop pressure against resistance as it should (and indeed as any positive displacement external gear pump should).

It is the result of a fault in the AHC Pump assembly

There are only the following possibilities for this situation, some are more likely than others. For completeness, here they all are, starting from the motor and working towards the Pump sub-assembly:

• The AHC Electric Motor 88264-60010 is faulty -- this seems extremely unlikely, given that the motor works when connected to 12 volt DC supply, The pump is working . ITs a bit stiff, but it runs - in both directions.

• The electric motor 88264-60010 is not engaging the Pump sub-assembly 48901-60010 properly – this seems highly unlikely -- but it is worth checking the small connector “shaft” 48977-60010 which passes through the milled aluminium housing 48905-60010 and through a seal 90311-10001. This tiny “shaft” connects the motor on one side of the housing and the driven gear in the Pump sub-assembly 48901-60010 on the other side – and it is worth being satisfied that all parts are engaging properly, I watched the opposite side of the pump , where the other side of the gear shaft it and i see that the ends of the shafts are spinning. - The tiny shaft is functioning!

• AHC Fluid is not reaching the Pump sub-assembly 48901-60010 -- this does not seem very likely -- nevertheless it is important to be satisfied that there is no blockage or restriction -- such as might be caused by gel or other gunk -- (a) at the base of the AHC Tank and where it joins on the housing 48905-60010, and (b) that there is no blockage of restriction in the fluid path through the housing 48905-60010 to the point at which the AHC Pump sub-assembly 48901-60010 picks up AHC Fluid. The simplest way to check this might be to remove the Pump sub-assembly and check that there is a good gravity feed of AHC Fluid from the AHC Tank. (I have wondered whether this can be checked by pushing a pipe-cleaner or piece of wire or similar through this passage -- but this might run into the Return Valve within the housing and cause confusion and/or disrupt the Return Valve), I blew air into the container from the opening and it escaped freely thru the botttom -- There is NO blockage - per your this does not seem very likely

• Air is being drawn into the AHC Pump sub-assembly 48901-60010 -- this is possible and certainly would cause DTC C1762– it is important to be satisfied that the following seals are working as intended, not wrongly fitted, loose, worn or damaged in some way which would allow air ingestion due to negative pressure (sucking) on Intake side of the AHC Pump sub-assembly 48901-60010 when it is operating:
  • seal 90385-08017 between AHC Tank and Housing 48905-60010, REPLACED with NEW
  • Seal 90311-10001 at small connector “shaft” between motor and AHC Pump sub-assembly 48901-60010, REPLACED with NEW
  • Large O-ring 90301-70003 between detachable outer cover 48913-60010 and Housing 48905-60010, REPLACED with NEW

• Any external gear pump (of which the AHC Pump sub-assembly is a micro example compared to industrial scale gear pumps) has a low pressure side (at the Intake) and a high pressure side (at the Discharge).

• In any external gear pump (including the AHC gear pump), the high pressure side and the low pressure side are separated by seals -- the design and location of seals can vary but the principle is always the same,

• In the AHC Pump sub-assembly, the relevant seals are:
  • the triangular-looking O-ring under the top-plate,
  • the O-rings on the gearcases,
  • the small O-ring 90301-06012 where the Discharge from AHC Pump sub-assembly joins the Housing 48905-60010 near the Return Valve, REPLACED with NEW

• If ANY of these three seals weaken or fail, or if during dis-assembly and re-assembly of the AHC Pump sub-assembly the top-plate is insufficiently tightened, then AHC Fluid WILL leak from the AHC Pump sub-assembly into the region behind the outer cover and from there, back to the AHC Tank, WHAT ARE THE TORQUE SPECS FOR THE 2 ALLEN SCREWS THAT CLAMP THE PART HALVES, AND THE LONGER ONES THAT CONNECT THE PUMP TO THE FRAME? I dont have a torque wrench for allen screws , but i can figure out something

• @BullElk highlighted this situation when he found that the O-rings on the gearcases required replacement and that rectified the no-flow condition in his AHC Pump -- @BullElk had stopped the leak and restored correct AHC Pump operation, WHat post # in this string is his description ? Or is this a totally different post ?

View attachment 3650654
View attachment 3650652

• What it is “The Notch”? Where does it go? In recent Posts by @suprasvobodea, @Moridinbg, @IndroCruise, there have been photographs and stories from three Countries (USA, Bulgaria but travelling in South America, and Australia), where three different knowledgeable people each have opened a package containing a NEW OEM Toyota/Lexus AHC Pump sub-assembly 48901-60010 – this means three separate NEW TOYOTA/LEXUS AHC Pump sub-assemblies fresh out of the box from the factory via IMPEX or PARTSOUQ. There may be other examples from IH8MUD Members but please forgive me if I am unable to recall all of them. Then each of the above persons has taken the top-plate off the sub-assembly -- and lo and behold -- pictures all show the “notch” on the gear-case correctly located (when assembled) below the By-pass Strainer and on Intake side of the AHC Pump sub-assembly!! Probably @BullElk would agree? Similar reports can be found in the 200 series Forum for which the AHC Pump sub-assembly is very similar (although not exactly the same). In the previous Posts this thread, @suprarx7nut also has confirmed the same location and orientation in his own observations. All of that to say that unless someone, somewhere (anywhere!) has better evidence, then that is the end of the story on the correct, as-designed, as-manufactured, purposeful location of the “Notch”.

• What is the purpose of the “Notch”? The “Notch” is an obvious and deliberate effort by the Pump designer/manufacturer to facilitate an exit pathway for the fluid trapped in between the meshing gear teeth as they emerge from the mesh. A different approach might have been to manufacture larger clearances between the components -- but that have may detracted from Pump performance. So the “Notch” is a compromise probably made to simplify manufacturing of a mass-produced item,

View attachment 3650655

• The high pressure fluid trapped in the gear mesh requires an exit path. This fluid cannot fight with the incoming fluid because then there would be no pressure difference to create a Discharge, just fluid going round and round inside the Pump. In gear pumps this exit path is via the fine clearances around the gearcases. In the AHC Pump, this path leads to the area in the top-plate surrounded by the triangular O-ring. Further exit is blocked by the O-rings on the gearcases in the AHC Pump sub-assembly -- provided that these O-rings are in good condition, I am working with a new pump that i opened, but the Origns and back up rings are brand new factory stock. I also installed the backup ring into the back half of the housing and made sure the O rings are just TOUCHING each other and not one is "stepped " on the other next to it.

• The exiting fluid then moves from the area within the triangular O-ring and passes through the By-pass filter and then on to the Intake side of the AHC Pump sub-assembly,

• In the AHC gear pump, the fluid in this exit path is at very high pressure -- this has the intended added benefit of increasing the pressure on the gearcases which in turn increase the force pressing the gears onto the floor of the housing, reducing clearances and reducing the fluid bypassing across the top and bottom surfaces of the gears, and enhancing Pump performance at the Discharge,

• There is a balance here -- if the top-plate is insufficiently tightened, then that can easily be the cause of multiple kinds of leakage within and from the AHC Pump sub-assembly to the outer case and the AHC Tank and be the cause of low flow and low pressure at the AHC Pump sub-assembly Discharge. If the top-plate is over-tightened, then that may inhibit gear rotation and cause the tiny connector “shaft” between the Motor and the AHC Pump sub-assembly to disengage or be damaged, resulting in reduced flow and pressure at the discharge (or maybe no flow at all),

• I mean no criticism or offence whatsoever to @suprasvobodea or anyone else when I say that in my personal opinion from far way, the cause of lack of discharge from the AHC Pump in the subject vehicle is due to the dis-assembly and re-assembly of the AHC Pump sub-assembly with the top-plate insufficiently tightened – resulting in loss of Discharge pressure and flow due to internal FLUID leaks at the seals. There is nothing about dis-assembly and re-assembly of the AHC Pump sub-assembly in the FSM -- so it is a matter of trial and error by those who choose to do so. The alternative is to replace Pump sub-assembly 48901-60010 as recommended by Toyota/Lexus, I THINK THIS IS THE ONLY EXPLANATION FOR WHY THE PUMP IS NOT MOVING FLUID . I WILL REMOVE THE COVER AGAIN , AND TIGHTEN ALL 4 ALLEN BOLTS , EVEN MORE & RE-TEST. I WILL REPORT SHORTLY IF THIS MAKES A DIFFERENCE. If this does not change anythign, then my only and final solution is to wait for the 2nd NEW pump assy to arrive from IMPEX - hopefully by friday.

• @suprasvobodea has advised that when he re-installed his new AHC Pump sub-assembly 48901-60010, with the “Notch” on the wrong side, there was no Discharge, ( SORRY, SOMETHING WAS MISS QUOTED , I DID NOT ASSEMBLE WITH NOTCH IN WRONG DIRECTION!) and the Motor had stalled in an over-current situation (hot leads). This is a new Pump, clearances are tight, it cannot work this way, so personally I don’t find ‘hydraulic lock-up’ surprising, because the fluid exiting the meshing gear teeth has nowhere to go, This is correct about clearaned and lock up, but i did not re-assemble with the notch in the wrong direction . I posted pictures previousl of what my gear notch is located and it mathced what you posted. The begs the quesion ... WHY DID THIS NOT WORK IN THE REVERSE POLARITY.....................???

• @Moridinbg has described some different experiences while nursing an old AHC Pump sub-assembly in his LC100 while traversing most of South America, including experiments with the “Notch” positioned on either side of the Pump and also reversing the polarity of the Pump Motor. Having followed his “Re-build” thread and his “Patagonia” thread, I can only salute the resourcefulness and ingenuity of @Moridinbg, both in the workshop in Bulgaria, and while doing diagnosis and roadside repairs in extremely remote environments in South America. I do wonder whether some of the effects he observed may be due to wear-related increase in clearances within the Pump, or, gearcase O-rings possibly were past their best? Only @Moridinbg could answer that ….

The attached Paper "The Fundamentals of Gear Pump Design" -- US Naval Research Laboratory - January 2022 -- may be of interest to those with an interest in the technicalities ....

This video may be a bit too long -- it shows a Master Mechanic instructing a young Apprentice on the workings of a gear pump and the location and purpose of the internal seals and the by-pass arrangements along the gearcase clearances. The example is a large-scale gear pump used to drive a log-splitting machine. The details are different but the principles are the same as in the tiny AHC Pump sub-assembly.

INDOCRUISE -
I have answered your questions in the above (post #100) in BLUE make it easier and more direct to follow.

 

[suprasvobodea]

My instinct tells me your disassembly of the pump isn't/wasn't the issue. You didn't let any magic out of it when you opened it up, haha.

To clarify in painful detail: You have the pump with the reservoir totally removed so that all you see is this (ignore red arrows, not my pic):
View attachment 3652479

And you fill that inlet column where the grommet goes from the reservoir (but the reservoir is NOT present) with oil.

Then you turn on the pump. Again, the reservoir is in a separate room, far away from this situation.

And the column of oil stays there? No fluid movement? It doesn't drain out at all?

REPLY>>> Yes, i have done the same and posted pictures of this today . and the fluid does NOT lower when 12V is applied. It will slowly LEAK out when I remove the black stopper in the outlet, but that's all. I think I will tighten down the 4 fallen bolts even more now and retest. That is what INDOCRUISE suggested in his reply post #102 .

 

[suprarx7nut]

Well, I am bewildered. Aside from some significant mis-assembly, I don't know how that wouldn't pump.

Thank you for showing pictures, though. It's clear the issue is within that pump.

If that were me, I'd mess with the pump assembly more. Meticulously crawl through the assembly of your pumps and see if you can spot anything.

 

[suprasvobodea]

Well, I am bewildered. Aside from some significant mis-assembly, I don't know how that wouldn't pump.

Thank you for showing pictures, though. It's clear the issue is within that pump.

If that were me, I'd mess with the pump assembly more. Meticulously crawl through the assembly of your pumps and see if you can spot anything.

Ok, I'm going to check this now. I will remove the cover, (drain the fluid BEFORE I remove the cover by turning it upside down and pouring it out the inlet top area, and then TORQUE down the 4 Allen bolts and see if this makes -my day! If this does NOT work, then my only other option is wait for another new pump to arrive from IMPEX - Japan ( and it WILL NOT BE OPENED !!)

 

[suprasvobodea]

Ok, I'm going to check this now. I will remove the cover, (drain the fluid BEFORE I remove the cover by turning it upside down and pouring it out the inlet top area, and then TORQUE down the 4 Allen bolts and see if this makes -my day! If this does NOT work, then my only other option is wait for another new pump to arrive from IMPEX - Japan ( and it WILL NOT BE OPENED !!)

oK, I just disassembled the pump for the 6th time. I removed the new little O ring for the outlet, the triangular-shaped O ring, and the Large cover O-ring. ALll are new and were replaced when I bought this new pump 2 months ago. I tightened the 4 Allen screws down - tight so there is NO possibility of leakage, I then inserted the Back up ring into the back half of the pump and the O ring on the gear shafts, one at a time, and made sure they did not "ride up " one of them. I expected this damn thing to start pushing Oil thru the outlet when applied 12 V.................
IT DID NOT !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

So, something is going on INSIDE this pump of mine. If I remember, there was another guy who had like 4 -5 pumps that he showed pictures of,, that were doing the same thing, NOT WORKING! Even the NEW pump he had, Did not work! The only one that did, was his old one!! but it was worn out and took a long time to go to H. I need to get this LX 470 running by this weekend so I can drive 1000 miles to Wisconsin to see my 90-year-old mother for her birthday. I have not driven my LX in 5 MONTHS! ITS TIME TO GET ER GOING!

At this time, feeling TOTALY like a failure as to making a simple gear pump, work ................ I can only wait for a 2nd New pump to arrive from IMPEX and install it. If ANYONE has a suggestion or insight as to why this pump is NOT working, please feel free to let me know..... I'll try it. The seals and back upright are all new on this pump so replacing them is pointless. INDOCRUISE, if you see this, your professional help is most welcome., I am almost out of gas. iM RUNNING ON VAPOR!. The only thing keeping me going are the 2 cornerstones of my life, MY MIDDLE NAME and personality,...........................

PERSISTANCE AND TENACITY!
I appreciate any additional. suggestions and help!

 

[IndroCruise]

Ok, I'm going to check this now. I will remove the cover, (drain the fluid BEFORE I remove the cover by turning it upside down and pouring it out the inlet top area, and then TORQUE down the 4 Allen bolts and see if this makes -my day! If this does NOT work, then my only other option is wait for another new pump to arrive from IMPEX - Japan ( and it WILL NOT BE OPENED !!)

From @suprasvobodea: This is correct about clearaned and lock up, but i did not re-assemble with the notch in the wrong direction . I posted pictures previousl of what my gear notch is located and it mathced what you posted. The begs the quesion ... WHY DID THIS NOT WORK IN THE REVERSE POLARITY.....................???

From @IndroCruise: My mistake -- apologies offered if I have misunderstood – I had no wish to add to the frustration and stress. I could see from your pictures where you have the “notch” shown on the correct side. I thought, wrongly, that you also had tried the same Pump with the “notch” on the wrong side.

Anyway, suggest think about what is happening when polarity at the Pump Motor is reversed.

• Direction of rotation of gears is reversed,
• The Pump Discharge is then asked to become the Intake,
• The Pump Intake is then meant to become the Discharge.

Question: When reversed, how does the Pump draw fluid somehow from the AHC system instead of from the AHC Tank??

Answer: It is extremely difficult to understand how this can happen. To do so would require that the Pump draws fluid past the closed Return Valve (located in the housing between the AHC Pump and the AHC Pump Motor) and then draws fluid past the closed Levelling Valves (further back in the circuit within the Control Valve Assembly). It also means that it is extremely difficult for fluid to be released as gear teeth exit the mesh in the gear pump (because the "notch" is not at the "new Intake" when the Pump is reversed). In this condition, lock-up of the Pump (no flow) is unsurprising, especially on a new AHC Pump.

Question: How is that @Moridinbg (and others) have had successful experiences reversing polarity?

Answer: @Moridinbg is very experienced in the AHC/TEMS system and his reports are factual -- best to ask him this question. My guess is that his report is related to an old, worn AHC Pump, and that internal leakage within the Pump was occurring -- possible in such a case. It is more likely (and unsurprising) that a new Pump with fine tolerances (no wear) and new seals, will lock (do nothing) when polarity is reversed.

It certainly was worthwhile following up on the suggestion offered by @suprarx7nut concerning elimination of air in the Pump -- this helped to eliminate an important possibility.

For my part, with the exception of the misunderstanding noted above, no "questions have been begged". My opinion remains as expressed in in Posts #84 and #85 (both with pictures) and especially in the list of bullet points graded from least likely to most likely set out in Post #98 (also with pictures). Maybe the less likely causes listed in Post #98 need to be be reconsidered now.

In short, it is very difficult to escape the conclusion that there is an assembly problem with the subject AHC Pump -- whether at the factory or when opened before installation in the vehicle. Maybe it will require installation of a known working AHC Pump sub-assembly to help resolve this issue?

Meanwhile, here are some more pictures with labels and explanations which may be of assistance:

Long ago @parkeyjack had some experiences with multiple non-performing AHC Pump sub-assemblies -- tagged in case he can offer further insights ....

 

[parkeyjack]

From @suprasvobodea: This is correct about clearaned and lock up, but i did not re-assemble with the notch in the wrong direction . I posted pictures previousl of what my gear notch is located and it mathced what you posted. The begs the quesion ... WHY DID THIS NOT WORK IN THE REVERSE POLARITY.....................???

From @IndroCruise: My mistake -- apologies offered if I have misunderstood – I had no wish to add to the frustration and stress. I could see from your pictures where you have the “notch” shown on the correct side. I thought, wrongly, that you also had tried the same Pump with the “notch” on the wrong side.

Anyway, suggest think about what is happening when polarity at the Pump Motor is reversed.

• Direction of rotation of gears is reversed,
• The Pump Discharge is then asked to become the Intake,
• The Pump Intake is then meant to become the Discharge.

Question: When reversed, how does the Pump draw fluid somehow from the AHC system instead of from the AHC Tank??

Answer: It is extremely difficult to understand how this can happen. To do so would require that the Pump draws fluid past the closed Return Valve (located in the housing between the Pump and the Motor) and then draws fluid past the closed Levelling Valves (further back in the circuit within the Control Valve Assembly). It also means that it is extremely difficult for fluid to be released as teeth exit the mesh in the gear pump (because the "notch" is not at the "new Intake" when the Pump is reversed). Lock-up of the Pump (no flow) is unsurprising, especially on a new AHC Pump.

Question: How is that @Moridinbg (and others) have had successful experiences reversing polarity?

Answer: @Moridinbg is very experienced in the AHC/TEMS system and his reports are factual -- best to ask him this question. My guess is that his report is related to an old, worn AHC Pump, and that internal leakage within the Pump was occurring -- possible in such a case. It is more likely (and unsurprising) that a new Pump with fine tolerances (no wear) and new seals, will lock (do nothing) when polarity is reversed.

It certainly was worthwhile following up on the suggestion offered by @suprarx7nut – it helped to eliminate an important possibility.

For my part, with the exception of the misunderstanding noted above, no questions have been begged. My opinion remains as expressed in in Posts #84 and #85 (both with pictures) and especially in the list of bullet points graded from least likely to most likely set out in Post #98 (also with pictures). Maybe the less likely causes need to be be reconsidered.

In short, it is very difficult to escape the conclusion that the there is an assembly problem with the subject AHC Pump -- whether at the factory or when opened before installation in the vehicle. Maybe it will require installation of a known working AHC Pump sub-assembly to resolve this issue.

Meanwhile, here are some more pictures with labels and explanations which may be of assistance:

View attachment 3653112


View attachment 3653113

View attachment 3653114

View attachment 3653130

Long ago @parkeyjack had some experiences with multiple non-performing AHC Pump sub-assemblies -- tagged in case he can offer further insights ....

Nope. Tried to forget as much AHC stuff as I learned. I still get the shakes and jitters whenever someone mentions AHC. Haha. I kid I kid. But kudos to everyone trying to still figure it out. I ripped that puppy out and put in traditional. Now I’m in an 80 series so definitely no worries about AHC. Just a bunch of other stuff that drives my OCD crazy.

 

[suprarx7nut]

@suprasvobodea When you ran the pump did it at least dribble out faster than when the pump was off? Was the effect small or literally zero?

If zero, any chance the motor and pup aren't quite coupled properly? I forget exactly how those interface, but is there a chance the motor is spinning, but it's not grabbing the pump gears?

 

[IndroCruise]

@suprasvobodea When you ran the pump did it at least dribble out faster than when the pump was off? Was the effect small or literally zero?

If zero, any chance the motor and pup aren't quite coupled properly? I forget exactly how those interface, but is there a chance the motor is spinning, but it's not grabbing the pump gears?

.... certainly worth checking -- as mentioned in second bullet point in Post #98 this thread.

Further to the list in Post #98 mentioned in Post #109, also suggest check all items external to the AHC Pump sub-assembly circled on the attachment, including torque on all circled bolts. No information is given on the torque for the two short bolts holding the AHC Pump sub-assembly together, maybe assume similar torques to other bolts shown.

It is acknowlededged that some items circled on the attachment have been replaced.

 

[suprasvobodea]

@suprasvobodea When you ran the pump did it at least dribble out faster than when the pump was off? Was the effect small or literally zero?

If zero, any chance the motor and pup aren't quite coupled properly? I forget exactly how those interface, but is there a chance the motor is spinning, but it's not grabbing the pump gears?

I check that by looking at the opposite end of the pump assy( the 2 little dimples where the gear shafts end) & I could see them spinning.

 

[suprasvobodea]

@suprasvobodea When you ran the pump did it at least dribble out faster than when the pump was off? Was the effect small or literally zero?

If zero, any chance the motor and pup aren't quite coupled properly? I forget exactly how those interface, but is there a chance the motor is spinning, but it's not grabbing the pump gears?

That’s the question I would’ve asked, and the strange answer is NO! it did not drizzle out any faster.!!????! One would think it would
So that tells me the pump simply is not pumping!!!
I JUST Do NOT UNDERSTAND THIS THING?!
I’ve disassembled it and reassemble carefully six or seven times.

 

[IndroCruise]

That’s the question I would’ve asked, and the strange answer is NO! it did not drizzle out any faster.!!????! One would think it would
So that tells me the pump simply is not pumping!!!
I JUST Do NOT UNDERSTAND THIS THING?!
I’ve disassembled it and reassemble carefully six or seven times.

Frustrations understood. Suggest do not be too hard on yourself -- your understanding is good. If the solution was easy to see you would have found it long ago.

You have mentioned at Post #103: I check that by looking at the opposite end of the pump assy( the 2 little dimples where the gear shafts end) & I could see them spinning.

This seems to mean that you have been able to run the Pump with the outer cover removed so that you could see what was happening??

Even if this is my misunderstanding, may I make the following suggestions? These could be considered while waiting for the new AHC Pump sub-assembly 48901-60010 to arrive

Remove the outer cover 48913-60010 (three screws) but leave the existing AHC Pump sub-assembly in place.

Again set up and run the test suggested by @suprarx7nut by filling the entry at the housing 48905-60010 with fluid (exactly as shown in your pictures at Post #103) but this time with the outer cover removed. (The outer cover is attached in your pictures at Post #103). Place some rags etc where needed because this idea may be messy.

The purpose of doing this is to see more clearly what is happening.

Late edit and clarification: Use tape or suitable binding to form a temporary cover only on that part of housing 48905-60010 where the Pump sub-assembly picks up fluid (see location in the picture in the next Post). Just enough cover is needed to prevent AHC Fluid escaping. This temporary cover does not have to be airtight and some air will be ingested by the Pump. This does not matter -- the point of the test is only to see where the fluid is going while also being able to see that the gears are turning -- this cannot be seen while the regular outer cover is in place.

If the gears are turning inside the AHC Pump sub-assembly, then there are these possibilities:

1. AHC fluid IS entering the Pump and IS arriving at the gears. If the gears are turning, then the fluid has to go somewhere -- either the fluid is discharged by the Pump (which is not happening in your tests), or, fluid is leaking from the sub-assembly as shown in the third picture at my Post #109. Such leakage cannot be seen while the outer cover is in place. This possibility seems less likely given all the work you have done and parts replaced but it is too early to abandon this idea without testing,

OR

2. AHC Fluid IS NOT entering the Pump and IS NOT arriving at the gears. Then there is no pumping action (or not much pumping action) and either there is no discharge or there is just a dribble. If AHC Fluid IS NOT entering the Pump and is not arriving at the gears, then suspect a blockage in the housing 48905-60010 between the fill point and the point at which the Pump sub-assembly picks up the fluid. This should be easy to explore.

OR

3. AHC fluid IS entering the Pump and IS arriving at the gears AND there is no discharge. If the gears are turning, and the AHC Pump sub-assembly seems healthy (no internal leaks across O-rings and seals) but there is no discharge, then a blockage might be suspected in the housing after the sub-assembly Discharge but before the Discharge from the overall assembly where the AHC pipe attaches (where the rubber bung is in place in your pictures at your Post #103). This may involve a malfunction of the Return Valve which is inside the housing 48905-60010. The Return Valve is spring-loaded and is meant to open under pressure when the Pump is operating. A malfunction or a blockage within or before the Return Valve is VERY unusual but it is possible. There is another small fluid Strainer in front of the Return Valve which may be a possible blockage point. This Strainer can be removed in a similar way to the Strainers inside the AHC Pump sub-assembly (see picture below). Removing the Return Valve mechanism is more complicated.

 

[IndroCruise]

Frustrations understood. Suggest do not be too hard on yourself -- your understanding is good. If the solution was easy to see you would have found it long ago.

You have mentioned at Post #103: I check that by looking at the opposite end of the pump assy( the 2 little dimples where the gear shafts end) & I could see them spinning.

This seems to mean that you have been able to run the Pump with the outer cover removed so that you could see what was happening??

Even if this is my misunderstanding, may I make the following suggestions? These could be considered while waiting for the new AHC Pump sub-assembly 48901-60010 to arrive

Remove the outer cover 48913-60010 (three screws) but leave the existing AHC Pump sub-assembly in place.

Again set up and run the test suggested by @suprarx7nut by filling the entry at the housing 48905-60010 with fluid (exactly as shown in your pictures at Post #103) but this time with the outer cover removed. (The outer cover is attached in your pictures at Post #103). Place some rags etc where needed because this idea may be messy.

The purpose of doing this is to see more clearly what is happening.

If the gears are turning inside the AHC Pump sub-assembly, then there are these possibilities:

1. AHC fluid IS entering the Pump and IS arriving at the gears. If the gears are turning, then the fluid has to go somewhere -- either the fluid is discharged by the Pump (which is not happening in your tests), or, fluid is leaking from the sub-assembly as shown in the third picture at my Post #109. Such leakage cannot be seen while the outer cover is in place. This possibility seems less likely given all the work you have done and parts replaced but it is too early to abandon this idea without testing,

OR

2. AHC Fluid IS NOT entering the Pump and IS NOT arriving at the gears. Then there is no pumping action (or not much pumping action) and either there is no discharge or there is just a dribble. If AHC Fluid IS NOT entering the Pump and is not arriving at the gears, then suspect a blockage in the housing 48905-60010 between the fill point and the point at which the Pump sub-assembly picks up the fluid. This should be easy to explore.

OR

3. AHC fluid IS entering the Pump and IS arriving at the gears AND there is no discharge. If the gears are turning, and the AHC Pump sub-assembly seems healthy (no internal leaks across O-rings and seals) but there is no discharge, then a blockage might be suspected in the housing after the sub-assembly Discharge but before the Discharge from the overall assembly where the AHC pipe attaches (where the rubber bung is in place in your pictures at your Post #103). This may involve a malfunction of the Return Valve which is inside the housing 48905-60010. The Return Valve is spring-loaded and is meant to open under pressure when the Pump is operating. A malfunction or a blockage within or before the Return Valve is VERY unusual but it is possible. There is another small fluid Strainer in front of the Return Valve which may be a possible blockage point. This Strainer can be removed in a similar way to the Strainers inside the AHC Pump sub-assembly (see picture below). Removing the Return Valve mechanism is more complicated.

View attachment 3653750

View attachment 3653752

View attachment 3653755

One more labelled picture added to assist @suprasvobodea and others with the explanations in my previous posts in this thread. [Picture late-edited to correct a mistake in labelling of fluid Intake from Tank].

The picture shows the Pump side of the housing 48905-60010 on which the AHC Pump sub-assembly 48901-60010 is mounted. This housing separates the AHC Pump and the Pump Motor which is mounted on the other side.

See also Late Edits in previous Post #115.

 

[IndroCruise]

One more labelled picture added to assist @suprasvobodea and others with the explanations in my previous posts in this thread.

The picture shows the Pump side of the housing 48905-60010 on which the AHC Pump sub-assembly 48901-60010 is mounted. This housing separates the AHC Pump and the Pump Motor which is mounted on the other side.

See also Late Edits in previous Post #115.

View attachment 3653919

One last thought to assist @suprasvobodea and others in the series of pictures posted earlier in this thread ....

If the AHC Pump sub-assembly is to be changed, it may be worthwhile to change out the seal 90311-10001 on the Housing 48905-60010 between the AHC Pump sub-assembly 48905-60010 on one side and the Pump Motor 88264-60010 on the other side. This seal serves two purposes: (1) prevents AHC Fluid leaking out, and (2) reduces the ability of air to leak in, with potential for DTC C1762.

As can be seen from the pictures below, this seal is located on the Motor Side of the housing. Separation of the Housing and the Motor is necessary to replace the seal.

Unless it is damaged, it should not be necessary to replace the small connector shaft 48977-60010
between the Motor and the Pump -- see fourth picture below ....

 

[suprasvobodea]

One last thought to assist @suprasvobodea and others in the series of pictures posted earlier in this thread ....

If the AHC Pump sub-assembly is to be changed, it may be worthwhile to change out the seal 90311-10001 on the Housing 48905-60010 between the AHC Pump sub-assembly 48905-60010 on one side and the Pump Motor 88264-60010 on the other side. This seal serves two purposes: (1) prevents AHC Fluid leaking out, and (2) reduces the ability of air to leak in, with potential for DTC C1762.

As can be seen from the pictures below, this seal is located on the Motor Side of the housing. Separation of the Housing and the Motor is necessary to replace the seal.

Unless it is damaged, it should not be necessary to replace the small connector shaft 48977-60010
between the Motor and the Pump -- see fourth picture below ....

View attachment 3654497

View attachment 3654498

View attachment 3654499

View attachment 3654500

INDOCRUISE

Thank you for your perseverance, I am almost to the breaking point, but your steadfastness, calmness, and true sincerity keep me going!

In your response, to my post about checking the gears to see if they were turning, that's correct, you CANNOT see them turning at the ends with the cover on. but if you remove it, then oil leaks out the depression area you labeled in post #116. If you take it off, the Oil you put in the top 1" opening where the tank sits, will flow out through that area picture identified in #116 with the labels you provide. Before I forget to tell you, I already installed a NEW seal 90311-10001 where the electric motor shaft connects to the small notched connector! The ONLY seal I have not purchased new, is the Triangular O-ring- I don't know the # number of this one. I can order that locally from a dealer here, but I don't know if its really critical to the pump's ability to work. if you think it IS NECESSARY, then I will order it tomorrow morning. Does this triangular O-ring critical to the operation /pumping ability of this assy? The O-ring and backup ring on the gear shafts that you show in several posts starting in #98 are NEW as they come with the pump sub-assy. so I don't need to replace them and I will be getting NEW ones on the NEW pump that I'm waiting on from IMPEX.
About the only thing I can think of to temporarily seal this " area" that is a cast in depression in the AL housing, is something like simple ... ..... Chewing GUM! I don't have any tiny rubber bungs like I used in the outlet thread area, but I guess I'll try that tomorrow morning!
(PASTE FROM late edit of #115 ) The point of the test is only to see where the fluid is going while also being able to see that the gears are turning -- this cannot be seen while the regular outer cover is in place. I'm not sure I understand your point, or what to infer after this test is performed, but I will do it in the morning. Hopefully, you will see this and comment. I still want to beat this thing and find out WHY THE HECK THIS NEW PUMP WILL NOT PUMP !!!!!!!!!!!!!!!!!!!!!!!!!!!!

Well, its almost midnight CST in TEXAS now, so I will turn in for the evening . I Look forward to hearing from you in the morning Sir!

 

[suprarx7nut]

Testing with the cover off will verify if the pump is spinning... I think. Since you don't see any difference in dribble/drip/flow with the pump on or off, that indicates perhaps the pump gears aren't actually spinning.

If they're spinning, you can focus on sealing.

If they don't spin, the problem is clearly with the drive connection between the pump and motor.

 

[suprasvobodea]

Testing with the cover off will verify if the pump is spinning... I think. Since you don't see any difference in dribble/drip/flow with the pump on or off, that indicates perhaps the pump gears aren't actually spinning.

If they're spinning, you can focus on sealing.

If they don't spin, the problem is clearly with the drive connection between the pump and motor.

Ok. It’s the simple stuff that sometimes gets missed, especially after months of trying everything. I’ll check it out this morning and report back

UPDATE >>> 6-14 9:30 AM
I removed the cover and poured oil into the area shown with an arrow( I don't have a text option when editing with this photo app) . I held it at an angle to maintain a small "pool " of oil in that cavity. When I applied 12V , IT DID NOT GO LOWER WHICH MEANS it's NOT PUMPING ANYTHING!. I removed the black rubber bung, and nothing came out (except leakage drips) .
I looked at the end of the gear shafts and they WERE SPINNING! So it is engaging, .. it's just not acting like a pump!!! The 4 Allen screws are torqued down very tightly, and there was NO seepage around the perimeter of the pump halves. so the new pump is NOT leaking (visibly) . Oh, I also removed the return access( Large Allen screw) that allows access to the 3rd screen and removed it with a screw -just like in the 3rd picture in #115 from INDOCRUISE, and it was clean as new. - so there is no blockage there either.
So, I have a new pump assy, that has spinning gears, but not moving any fluid thru it. It has all new o-rings except for the one that forms a triangle.! I will order that O-ring as well, but I don't know the part number. If anyone has this, please let me know.
Otherwise, I don know what else to do, except wait for another new pump assy to arrive from IMPEX,.... sometime in the future -( they have the absolute LOWEST prices on these kinds of parts ( the equivalent price in the states online is $419-489 dollars!)

The frightening thing is, All I did was open the thing up to check the little screens after I installed it and removed it when I was still getting the damn 1762 error code.