HELP! AHC Pump Issue After Reservoir Drain/Refill (1 Viewer)

[Wes Gardner]

Hello Cruiser gurus!
I'm having an AHC issue on a new-to-me 2008 LX
With no history of AHC service from Lexus I decided to flush AHC... didn't seem like too big of a deal from the reading I did
I dropped AHC into LOW mode, checked the reservoir (which didn't much fluid in it), drained the reservoir and refilled with 2L of fresh lovely pink AHC fluid. After restarting the truck the pump begins to make this awful whine like it's trying to pump fluid but there's nothing there. Tried restarting the truck a couple of times but was worried about burning up the pump so I stopped. I check TechStream and I get the error "abnormal oil pressure". If I clear the error in TS the pump will restart only to begin whining again immediately (see video here)
I've read through quite a few different AHC problem threads but TBO this is all very new and I'm a lot confused.
I'm assuming there is either an air bubble somewhere preventing fluid from entering the pump or even worse, some debris blocking the line. That being said, I'm not sure how to move forward from here.
Any help would be greatly appreciated

-----EDITED-----
Here's what happened...
1. Dirty fluid was put into my AHC reservoir which clogged the pump
2. I removed the reservoir and pump for cleaning
3. I cleaned a gel-like substance from the exterior pump filter
4. I took the pump-head apart to clean the interior filters and broke the pump
5. I ordered a new pump from Dubai and purchased new AHC fluid from Lexus
6. I installed the new pump and inspected all AHC fluid before transferring to the reservoir
7. Two flushes later, the LX is back to normal

This is what I learned...
1. DO NOT transfer AHC fluid into your reservoir before inspecting it. Pour the fluid into a clear container first. If it's dirty you'll know instantly as it will have a gel-like substance floating in it (see difference here)
2. DO NOT remove the the filter in the filler neck when transferring fluid to the reservoir.
3. If your pump gets clogged and you need to clean the filter, do not take apart the pump head. You can remove the head from the motor but do not separate the two parts of the pump head from each other. I'm 100% convinced this is what broke my pump.

 

[radman]

Hey Man!
(Wes and I talked on Friday, and I may try to go see him this week if it doesn't get sorted out)

I've never heard of the pump loosing prime after the reservoir drain/refill - It's usually when the Res isn't kept full of fluid during bleeding. the only thing I can think of is that you somehow got every last drop out of there during siphoning, but I still can't see how any air could have gotten in when you added the new fluid.

Have you tried initiating a lift during the pump noise?

I'm not sure of the proper way to "bench bleed" the pump, but I remember someone reversed the polarity on the pump to get it to run backwards
I'm not saying to do that yes, just that there might be a few easy things to try.

Suspension FSM is attached.

here's a link to a few guys that have successfully gotten pump working again:

AHC Flush failure

My 2008 LX570 with 133,000miles, About the last 5K miles or so miles I noticed the ride was getting stiff feel and hard, I wanted to try flush before buying globes. I decided to do AHC flush that failed. After doing a standard flush the car is now a bump stops and will not go up. I then...

forum.ih8mud.com

Help - AHC problem while changing fluid

Those square plugs are from Satan. They have itty bitty crimp releases in the corner but to crimp with enough force you have to be too close to the secured part so there is no room to push them out. Cut and replace much more sensible On the road update. After about 60 miles the check ahc came...

forum.ih8mud.com

edit: after reading the second thread, maybe you're not fighting a air/priming issue. maybe you had some debris fall in and clog the lines?

 

[PDoyle]

Where did you buy the fluid?

 

[Wes Gardner]

Have you tried initiating a lift during the pump noise?

I have. The truck seems like it wants to move up but it doesn't get anywhere before the error code pops up and turns off the pump

 

[Wes Gardner]

Where did you buy the fluid?

Toyota dealership just down the road from me

 

[Wes Gardner]

News...
Moved the truck back into the garage this morning and started it up (AHC is OFF at this point)
Turned AHC on and now when the pump runs there is fluid coming up the fill pipe of the reservoir out onto the ground

 

[NewBLX570]

Do you have a guess on why the pump initially failed post bleed? What do you think remedied the lack of pressure?

 

[Wes Gardner]

Do you have a guess on why the pump initially failed post bleed? What do you think remedied the lack of pressure?

Unfortunately there still is no pressure. The pump will come on and is very loud, runs for 30 seconds or so then shuts off with the pump pressure error. If I clear the error I get the same process again.

 

[PDoyle]

What kind of sound is the pump making? Like a knock sound or a high pitched wine?

 

[Wes Gardner]

Small update...
Tried bleeding the 5th accumulater but nothing came out. Now when I turn on the truck the pump runs for maybe 2-3 seconds and then stops with the "pump pressure" error. The tone of the pump is now totally different than it was but only runs for a short time.
Still trying to find the right answer...

 

[Wes Gardner]

What kind of sound is the pump making? Like a knock sound or a high pitched wine?

It's a whine. There's a video link in my first post

 

[PDoyle]

A high pitch wine from (what I'm reading) means the pump is cavitating.
Cavitation is the formation and collapse of air cavities in the liquid. When the pump cannot get the total volume of oil it needs, cavitation occurs.

A knocking sound means aeration.
Aeration occurs when air enters the pump cavity from an outside source.

 

[chalice]

That is the SAME exact sound my pump made after a flush. I have waay too much content in my thread in sig. Long story short, seems like it was debris in fresh AHC fluid. I cleaned the filters multiple times that are internal, but ultimately replaced the pump to speed things up.

If you do decide to clean your filters - mark gears to make sure they are clocked correctly when reinstalled.

//edit

After taking the pump in and out like 3 times I decided to bench bleed, grabbed an alligator clip adapter from harbor freight and cut the ends off. I made sure to get a higher amp rating one they had. But, I couldn't get the pump to build pressure - again make sure you clock gears correctly.

 

[radman]

check out this post:

Help - AHC problem while changing fluid

Today I’ve attempted to change the fluid in my 2011 LX. I pumped out the old fluid in the tank per the pdf I downloaded on here, and refilled to above the max line. While draining the first bleed point, I Inadvertently removed about 12oz of fluid from the first Bleed point (rh front). I then...

forum.ih8mud.com

 

[Wes Gardner]

check out this post:

Help - AHC problem while changing fluid

Today I’ve attempted to change the fluid in my 2011 LX. I pumped out the old fluid in the tank per the pdf I downloaded on here, and refilled to above the max line. While draining the first bleed point, I Inadvertently removed about 12oz of fluid from the first Bleed point (rh front). I then...

forum.ih8mud.com

If you mean this...

"Turn car on w/techstream running, clear code, go to AHC and force a front right or left height test. With a cleared code it should force it to raise"

Once I clear the code the pump immediately start again. Within 2-3 seconds I get the code again and everything stops.

 

[PDoyle]

That is the SAME exact sound my pump made after a flush. I have waay too much content in my thread in sig. Long story short, seems like it was debris in fresh AHC fluid. I cleaned the filters multiple times that are internal, but ultimately replaced the pump to speed things up.

If you do decide to clean your filters - mark gears to make sure they are clocked correctly when reinstalled.

//edit

After taking the pump in and out like 3 times I decided to bench bleed, grabbed an alligator clip adapter from harbor freight and cut the ends off. I made sure to get a higher amp rating one they had. But, I couldn't get the pump to build pressure - again make sure you clock gears correctly.

So you used the same fluid and installed a new pump ?

 

[Snafu13F]

Your issue sounds very similar to mine. I suspect some sort of clog was introduced with the new fluid. It’s sounds like your pump is cavitating. I was able to eventually get mine functioning properly through multiple bleeds, and intermittently running the pump in reverse to prime it for the next bleed. It did take a few weeks before the system worked perfectly all the time. Whatever material was clogging it has a lot of different spots to work through before it finally made its way into a globe, where it could do no more harm.
I used this set of procedures for mine :

A. Get yourself a test setup. Either a set of wires long enough to run to the battery directly or an extra battery. Unplug the large gray power plug to the pump. You can then use alligator clips to directly power the pump. everse the clips to run it in reverse. Don’t bother with techstream or clearing codes for these procedures, they’re not necessary at this point. You are directly running the pump to force fluid through the lines, allowing you to bleed any air or break up any clogs. I felt that running the pump in reverse for 5-6 likely eventually broke up the clog enough to begin passing it(like a kidney stone surgery).

1.fill your reservoir past the high mark. I don’t recommend removing the filter in the filler line, it will introduce air if you fill the reservoir too quickly
2 bleed from the furthest point. (Driver front, passenger front, driver rear, passenger rear) I let it go all the way down to the bump stop before closing the bleeder. Check the fluid level in the reservoir after each bleeder.
3. Use a piece of hose on each bleeder into a clear, DRY bottle. You want to be able to see even micro bubbles, and you DONT want to allow any water into the fluid if you’re recycling it. I know it’s expensive, but I bought fluid for a second full 5l flush. It was worth it.
4. Bleeding the 5th accumulator didn’t make any difference for me, no bubbles. Others have had it matter.
5. be patient. I didn’t think it was helping until my 3rd bleed.

good luck, and feel free to contact me if you need clarification or additional help.

 

[radman]

Unplug the large gray power plug to the pump. You can then use alligator clips to directly power the pump. everse the clips to run it in reverse.

others have said that the pump isn't self priming, and you have to "bench prime" it. Would you agree to this?

Does running the pump in reverse push fluid back into the reservoir?

Lastly, any idea why his fluid was spilling out of the fill tube?

 

[Snafu13F]

The pump is not self priming per the techs I’ve spoken to. Bench priming it is done by reversing the pump, pulling fluid from downstream into it. In theory, it pushes fluid back into the reservoir. But, if there is air in the pump or line, you may not see much change.

The only reason fluid should spill from the fill tube is if the reservoir is vastly overfilled or there a large pressure build up within the pump. That would be consisten with an air locked pump. I would bench prime and test the pump several times before starting to bleed.


I am regretting not taking a couple dozen pictures of the pump when i had it apart before. It makes more sense when you can see how the internals work.

 

[Wes Gardner]

good luck, and feel free to contact me if you need clarification or additional help.

Quick question...
From your experience what was the most efficient method for getting to the pump's power plug? What do I need to remove? More importantly, what can I leave on? Do I need to remove the bumper cover?
I'm sure it's not near as bad as it is in my head but it does look intimidating when you peel back that mudflap lol
I will get lots of pics and document this, whether it fixes my issue or not...