So today we had a nice day and I decided to tackle the AHC fluid flush that needed to be done. Things went smoothly up until I tried to bleed the Height Control Accumulator. The bleed screw was completely rusted and ended up snapping right off. I tried drilling and tapping it out but had no luck, so I decided I should replace the entire Height Control Accumulator unit rather than running it on a bleed screw with questionable integrity. I found a good deal on a new unit which will be here soon, but I had no success in finding a how to or a tutorial on how to replace it. The bottom bolts look easy to remove, but from what I can see there are two more bolts that bolt on top of the frame rail that seem impossible to get too. Anyone have any ideas on how I would go about replacing the Height Control Accumulator? Is there an easier way to get to the bolts on the top of the frame rail? Thanks
Removal of Height Control Accumulator?
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Removing the Height Control Accumulator (HCA) is PITA!! Mine was changed out by my friendly independent mechanic because he has lots of experience, he has a hoist, he is immune to knuckle damage, he had the patience for the job and the mess ends up in his workshop! In my case, the HCA bleeder valve could be opened and the HCA hydraulic pressure and fluid in the HCA could be released.
Before we get to the bolts etc and the removal of a HCA without opening a broken bleeder valve, some hydraulic background needs to be considered ….
Theoretically (meaning unless it is damaged, leaking or or not working properly), the solenoid valve at the front end of the HCA is “normally closed” – meaning that this valve remains closed and holds back the AHC fluid (and the pressure) in the HCA unless the solenoid valve is powered and opened by the AHC Electronic Control Unit (ECU).
The HCA solenoid valve opens only when
- the driver raises the vehicle when it is at rest or at speeds less that 25kph (16mph), and,
- the ECU causes the HCA to be recharged by the AHC Pump after a raise (the recharge may start during the raise).
So, if the AHC system is healthy, the HCA plays no other role in the vehicle suspension at any other time. Specifically, when its solenoid valve is closed, the HCA is hydraulically isolated from the ‘globes’ and the ‘shock absorbers’. So the HCA cannot be depressurised by opening the bleeder valves at the ‘globes’ because the HCA is isolated by the solenoid valve on the front end of the HCA.
Removal of the HCA first requires discharging its stored hydraulic pressure by opening the bleeder valve located next to the solenoid valve – as described in the FSM
But what to do if the bleeder valve is broken and cannot be opened???
The pictures at the end of the following post may help to visualise the situation:
LX470 AHC System Individual Parts What Are They Used For? - https://forum.ih8mud.com/threads/lx470-ahc-system-individual-parts-what-are-they-used-for.1231400/#post-13473787
And some of the background in the next following post also may be helpful:
AHC Accumulator Bleed Valve -- broke off. - https://forum.ih8mud.com/threads/ahc-accumulator-bleed-valve-broke-off.961362/page-2#post-13493310.
In particular, before removing a charged HCA, I would think about how to discharge the hydraulic pressure for safety, maybe along the lines suggested by @YvesNL , after double-checking that the supply voltage to the solenoid actually is around 12 volts, as measured at the electrical connector at the rear of the HCA):
AHC Accumulator Bleed Valve -- broke off. - https://forum.ih8mud.com/threads/ahc-accumulator-bleed-valve-broke-off.961362/page-2#post-12201571
The @YvesNL method would be very messy and the hazards of release of high pressure fluid from a pressure vessel must be managed very carefully. Before operating the solenoid valve, an improvement on the @YvesNL method may be to loosen and redirect the pipe which runs from the HCA to the Control Valve Assembly into a well-secured plastic bottle – well-secured because the fluid discharge pressure will be high and may be violent!
The HCA should remain firmly in position on the vehicle while it is being depressurised – it must not be allowed to become a heavy and very dangerous projectile.
**** INDUSTRIAL GRADE EYE PROTECTION, GLOVES, SKIN PROTECTION AND HYDRAULIC EXPERIENCE ARE ESSENTIAL FOR THIS PROJECT.
**** EYE DAMAGE AND INJECTION OF HIGH PRESSURE HYDRAULIC FLUID THROUGH THE SKIN MUST BE AVOIDED.
**** USUAL CARE MUST BE TAKEN TO AVOID INJURY FROM QUICKLY DROPPING VEHICLE WHEN WORKING ON AHC.
With the HCA safely depressurised and with no chance of an accidental high pressure fluid discharge during removal, attention can go to the two bolts securing the HCA to the top of the chassis rail. Yes – these are difficult but not impossible to remove. It is best to have the car on a hoist so that these bolts can be approached more easily from the inner side of the chassis rail rather than the outer side.
All things considered and noting the hazards and unless holding relevant personal skills and experience, it is recommended that this project be taken to a specialist workshop.
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- Thread starter
- #4
Hey thanks a lot for your input, I ended up ordering another bleeder valve from Lexus so I could compare the broken one to the new one, it looks like I've still got about 7-8 threads worth of bleeder valve still inside the accumulator which gave me enough confidence to finish flushing and bleeding the rest of the system. It holds pressure just fine for now, but I will definitely be looking around to see if there's anyone around my area that could replace the accumulator as a reasonable price. I never realized how dangerous it was to do this job until you replied so I likely wont be doing it myself. I called my local Lexus dealer asking for a quote, they were saying that the hydraulic lines typically break if undone so they wanted me to have those done along with the accumulator. Quote ended up being almost 5k... Yikes. I'll keep looking around to see if I can find someone that has experience with these that could do it for a more reasonable price. But if worse come to worst I'll try putting 12 volts to the solenoid. Thanks a lot for your help!
ramangain
Clarksonian disciple
Lines will break = typical AHC worry mongering upsell
Lines normally break so let's quote out all the lines? Facepalm.
They're irrationally scared and in turn, grossly over-quoted you to avoid your business. That's sad.
- Thread starter
- #7
Yeah I figured it was kind of bull, lines look fine to me, rust free
Edited 22nd May 2021: Mistake in pipe labels on pic of Height Control Accumulator noticed by @patchagan , now corrected
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
There is a lot of detail in these posts because the title of your thread makes it easy for others to find and these problems with the Height Control Accumulator will happen more often as LC100/LX470 vehicles get older -- so the posts may help someone .....
The frozen remnant of the bleeder valve is likely to stay safely in place in the Height Control Accumulator (HCA) for all time unless efforts are made to dislodge it. The AHC system will continue to work just fine so long as the solenoid valve at the front of the HCA works properly when required.
The AHC system still can be bled via the bleeder valves on the Damping Force Control Actuators to which the ‘globes’ are attached. This will not be perfect but it is far better than not bleeding. Given enough discharge/recharge cycles – meaning multiple cycles of lowering and raising the vehicle which causes the AHC fluid in the HCA to empty and refill – then the old fluid eventually will be diluted by new fluid added at the AHC tank and as fluid is cycled out of the HCA and leaves the AHC system via the bleeders at the Actuators.
So unless there are other problems with AHC operation, dealing with the HCA and the broken bleeder is not urgent and can be left on the “when convenient” list.
Some past threads have mentioned repair using an Ezi-out to remove the stuck bleeder valve – the general idea is illustrated in this video but is not specific to the HCA:
.
The point is that there really is not enough room to do something like this with HCA in situ on the vehicle chassis. Even if it this method was possible, great care would be needed to safely manage the release of any stored hydraulic pressure. For this reason, it would be better and safer to deal with the HCA and the problematic broken bleeder in a workshop after the HCA has been removed carefully and safely from the vehicle.
There are two pipes attached to the HCA – one from the AHC Pump to the HCA via the Attenuator, and, one short pipe from the HCA which runs over the top of the chassis rail to the Control Valve Assembly which is mounted on the inner side of the chassis rail.
If the solenoid valve in the HCA is tight internally (meaning not leaky nor faulty) then hydraulic disconnection should not be difficult. It is worth checking the operation of the HCA solenoid valve while it is still in the vehicle as described in previous posts. If the valve is faulty or if the pipes are frozen or weakened with rust, then be prepared to manage a messy discharge during disconnection and take care of personal safety (especially eyes), also as mentioned in the previous posts.
Repair or replacement then can be considered.
Consider costs of ‘worst case scenario’: Replace Height Control Accumulator (HCA) and relevant ‘pipes’.
Cost: Replacement Height Control Accumulator – Part No. 49130-60010:
Toyota Parts Center Online | Genuine Parts & Accessories - https://parts.toyota.com/ (USA)
USD1.095.62 (free shipping, Dealer discounts)
Partsouq (UAE)
USD394.64 + USD79.43 shipping
Megazip (Singapore)
USD455.92 + USD105.24 shipping
Amayama (Japan)
Will not ship due to pressure content of HCA
LexusPartsNow (USA)
USD810.18 + shipping?
eBay (USA)
USD442 to USD514 + shipping
Cost: Replacement ‘pipes’ actually called ‘tubes’:
Go to Height control (auto-leveler) for Toyota Land Cruiser UZJ100L - Genuine parts - https://toyota-usa.epc-data.com/land_cruiser/uzj100l/3704/chassis/4805/ -- another great place to identify AHC part numbers, including for Height Control Accumulator and pipes (Toyota/Lexus calls steel pipes ‘Tubes’ and flexible pipes ‘Hoses’). This site then directs to Amayama site for item cost and shipping cost, then can compare with other sources. For example:
USD146.37 48984-60022 Tube No. 4 + shipping cost, according to Amayama
USD 90.61 48981-60021 Tube No. 1 + shipping cost, according to Amayama
(Examples only – identification of actual parts needs to be checked).
The obvious point is that it seems very hard to make the ‘worst case scenario’ of replacing the Height Control Accumulator (HCA) and relevant ‘pipes’ add up to anything like USD5,000.
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cruiserpatch
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Actual Part Numbers for "tubes:"
Tube inlet into HCA: (the larger tube, 14mm)
Part No. 48982-60042 $65.07 USD at Marietta Toyota in Atlanta.
"Tube, Height Control, No. 2"
Tube outlet from HCA: (smaller tube, 10mm)
Part No. 48986-60011 $114.47 USD at Marietta Toyota in Atlanta.
"Tube, Height Control, No. 6"
I just rounded the bolt-head on tube No. 2 trying to get it out. I'm not sure how to get it off without cutting it.
cruiserpatch
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Update on some items. Might start a new thread if this interests anyone.
Backstory:
I recently attempted to replace my HCA but Tube No. 2 (Part No. 48982-60042) was extremely stuck in the HCA. I rounded off the plug for Tube No. 2 and wound up having to cut it off. I purchased a new one from Toyota, five bleeder screws and five rubber boots.
I was able to replace the AHC line without even tearing apart the entire truck (I'll try to explain but it took hours of shimmying, trial, and error).
I started by removing the old AHC Tube No. 2, stretching and maneuvering it out starting with the reservoir side (the side running along the frame toward the AHC pump). Once the frame side is able to move and all the plastic clips have been disconnected, it is impossible to get the tube out without removing four bolt that hold the crossmember to the PS frame rail. Once these four bolts are removed, I also removed the counter weight to create more working room. At this point you're able to pull the rest of the tube towards the passenger side from the HCA.
This process took ages and many frustrating moments. Make sure to pay attention to how the tube is routed around the exhaust, transmission, other tubes/lines, cables, etc. Once the old tube is out of the way, reverse the process and put the new part into place. I found that inverting the tube and rotating it 180 degrees a few times (this would have been so much easier with a vehicle lift) helped maneuver it through all the miscellaneous stuff between the frame and body.
This is probably a good time to admit that this may not ever be duplicated by anyone in their right mind. I still don't entirely understand how I was able to put in the new part.
Next steps for me are to remove those rusty bolts holding on the globe and globe housing. Time for a refresh.
This has quickly devolved into a ramble post. Hopefully this can help someone.
Backstory:
I recently attempted to replace my HCA but Tube No. 2 (Part No. 48982-60042) was extremely stuck in the HCA. I rounded off the plug for Tube No. 2 and wound up having to cut it off. I purchased a new one from Toyota, five bleeder screws and five rubber boots.
I was able to replace the AHC line without even tearing apart the entire truck (I'll try to explain but it took hours of shimmying, trial, and error).
I started by removing the old AHC Tube No. 2, stretching and maneuvering it out starting with the reservoir side (the side running along the frame toward the AHC pump). Once the frame side is able to move and all the plastic clips have been disconnected, it is impossible to get the tube out without removing four bolt that hold the crossmember to the PS frame rail. Once these four bolts are removed, I also removed the counter weight to create more working room. At this point you're able to pull the rest of the tube towards the passenger side from the HCA.
This process took ages and many frustrating moments. Make sure to pay attention to how the tube is routed around the exhaust, transmission, other tubes/lines, cables, etc. Once the old tube is out of the way, reverse the process and put the new part into place. I found that inverting the tube and rotating it 180 degrees a few times (this would have been so much easier with a vehicle lift) helped maneuver it through all the miscellaneous stuff between the frame and body.
This is probably a good time to admit that this may not ever be duplicated by anyone in their right mind. I still don't entirely understand how I was able to put in the new part.
Next steps for me are to remove those rusty bolts holding on the globe and globe housing. Time for a refresh.
This has quickly devolved into a ramble post. Hopefully this can help someone.
cruiserpatch
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The tube labels on your photograph diagram are actually incorrect. The larger (14mm) tube into the HCA is the inlet tube from the AHC pump assembly (runs up the PS frame rail). The smaller (10mm) tube out of the HCA runs to the "control panel" assembly on the Driver's side frame rail.
Thank you @patchagan -- there definitely was a mistake in the labels in my pic of the Height Control Accumulator far above, now "Late Edited" with correct labels at Post #8. Apologies offered to all for any confusion caused.
It is not particularly relevant but there are some differences in pipe routing between LHD and RHD vehicles. The AHC Pump assembly and pipe down to the Attenuator and onwards to the Height Control Accumulator are all on the Left Hand Side in a RHD vehicle, with the pump itself oriented on the forward side of the overall AHC Pump/Motor/Sensors/Tank assembly. This done in the factory build to provide room in front of the RHD driver for the brake master cylinder and its accumulator. Interestingly, the pipe at the pump outlet is the smaller diameter pipe but changes to the larger diameter after the Attenuator and onwards to the Height Control Accumulator.
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cruiserpatch
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Interesting about the LHD vs RHD. Thanks for the clarification. I missed the edit apparently.
To Crusier Patch-
Hello,
I unfortunately have a broken bleeder on my southern LX 470 (Texas-234K miles) too! I thought about trying to drill out the sheared bleeder stub in situ, but - No Tempo LImit posted earlier is probably correct... drilling out and using an extractor, while on jack stands, lying on your back, and drilling with a hand drill, completely parallel to the stud, is nearly impossible. So...............
I decided to REMOVE the Accumulator.. and what a PITA it is!! Ya'll are right about this procedure.
Ok, so as I'm removing the larger supply tube 14mm, and using a crowfoot, flare wrench, after 2 days soaking in PB Blaster,, then using a MAPP gas torch to heat it, and finally banging ( shock) on the accumulator,.with a BFH....... I managed to get the damn thing loosened & eventually removed. But not without rounding off the sides like (CRUISER PATCH did in a similar post ) The other connection to the Accumulator- 10 mm flare nut I also heated with a torch and soaked in PB blaster, and it came out easily.
Ok, so there's the background ... now my question guys...
There are ( 2 )12 mm bolts ON TOP of the frame rail in addition to the 2 on the side ( which you can easily remove) The fwd one is accessible after removing the pressure globe and the bracket for the running board. HOWEVER... the rear bolt is not accessible on either side of the frame. On the inboard side are 4-5 fluid lines, and on the outboard side, is the accumulator. There is a small gap on the outboard side to move the end of a 12mm wrench, but I don't see how to put the box end over the head of the bolt! This part was installed at the factory BEFORE the body was fixed to the frame ( no thought was given to how to remove those 2 bolts in the future obviously by any mechanic or Ih8MUD groupie like us).
But somehow, several people have removed their accumulators and removed that "hidden " rear bolt.
My question is ..HOW DID YOU DO IT?? is there a special service tool wrench with two 90deg "S-" bends I need to make to reach the head of the 12mm aft bolt on top the frame rail?
I am about to get a Sawzall and just the rear bracket off ( if I can get the blade in the gap between the frame rail ) and simply ignore that 4th top bolt when re-mounting the accumulator
cruiserpatch
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I invested in a 12mm flex head ratcheting wrench for this job. Came right out
I have a set of these flex ratcheting wrenches.,,, But how did you hold the socket end on top of the rear bolt, and WHICH side of the frame did you have the wrench? The Inboard has 4-5 steel tubes in the way & there is NO clearance to move a wrench much less apply pressure to the bolt head, and other things so that is not possible, outboard is the accumulator, and there is a narrow space between the accumulator and the steel body ... What am I missing ..? There is a secret that the successful removals had, that i need to discover or learn!
I have a set of these flex ratcheting wrenches.,,, But how did you hold the socket end on top of the rear bolt, and WHICH side of the frame did you have the wrench? The Inboard has 4-5 steel tubes in the way & there is NO clearance to move a wrench much less apply pressure to the bolt head, and other things so that is not possible, outboard is the accumulator, and there is a narrow space between the accumulator and the steel body ... What am I missing ..? There is a secret that the successful removals had, that i need to discover or learn!
I hit the same point when I was trying to remove mine and never figured out the secret. I ended up taking inspiration from the rear shock removal threads and drilled some access holes to come in from the top. Here’s a pic of the hole locations if you want to go that route.
Does anyone know the part number to replace that black rubber/plastic solenoid shroud cover at the end of the height control accumulator?
Do you happen to know the part number to replace that black rubber/plastic solenoid shroud cover at the end of the height control accumulator?
cruiserpatch
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I don’t know…sorry
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