Changing out the AHC suspension fluid?

hoser

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I've adjusted the AHC sensors on my LX to give it some lift. Now the fluid is low so I might as well flush and bleed the system instead of just adding--afterall the fluid does get pretty hot and is subject to moisture.

So, anybody know if there is a specific order to do this? Here's a diagram where you can see the "bleeder plugs" on the accumulators. Now what?

EDIT: since this thread was started 5 years ago, others have put together more detailed step-by-step instructions. See this thread:
https://forum.ih8mud.com/100-series-cruisers/438560-ahc-fluid-change-how-need-input.html#post6127557
bleed.gif
 
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CTapia

 
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Hoser,

Sorry, I don't have the answer to your question, but how about more details or a write up on how to adjust sensors for the lift?
 

powderpig

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I do not have a procedure for you but the fluid is quite spendy, and toyota only reccommends it stuff for the system. 30-35 a gallon. later robbie
 

hkeller

 
 
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Hey. I just did this on our LX. I downloaded an entire set of step by step instructions from the Toyota technical site. I think I paid $10.00 for one day access to the site. Unfortunately, my wife threw away the pages I printed and I can't remember exactly how I did it. It was pretty easy, though. Do use a hose on the bleeder plug to direct the fluid into a catch bottle, as the emulsified fluid comes out under a great deal of pressure. Take a look at that Toyota site, the instructions are good.
 
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This is how we usually do it at work (no rocket science), just be careful you don't squish your melon!! One can of the ahc fluid is usually plenty.
1. Set the vehicle all the way to low (Reservoir full)
2. Remove all of the old fluid from reservoir. Fill with new clean fluid, I usually put the whole can in. 3. Start vehicle and let suspension equalize to "n" position.
4. Turn vehicle off.
5. Start at one of the back accumulators (doesn't matter which one) and using a hose on the bleeder, open very slowly and let weight of vehicle push fluid out. Close bleeder when vehicle is close to bottom.
THIS IS THE STEP YOU COULD GET SQUISHED IF YOU ARE NOT CAREFUL!!!
6. Start vehicle and repeat steps for each corner accumulator.
7. Usually one cycle at each corner is sufficient. If you are going to do it more than once you will need more than one can of fluid.
Cautions - don't crack bleeders while car is running. Vehicle will try to compensate for the leaking corner and you will have a big high pressure mess.
Fluid resembles very slippery brake fluid and is a PITA to clean up - so keep that in mind.
Also this is usually PM at 60,000 miles.
Questions let me know.
 

hoser

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EDIT:
When following the steps above (specifically #5), Ben meant to say "start at one of the back 'Damping Force Actuators.'" See the diagram in Post #1 to see what it looks like. I also bled the "Height Control Accumulator" and did that till the fluid ran clear. Though I'm not sure it was necessary.


LexusBen-You said this is normally done at 60K intervals. Is that standard for all Lexus Dealerships or just yours? I've never seen it mentioned on the 60k service.

CTapia, It was pretty easy to adjust the height. I will post what I did so far but I'm still not quite done fiddling with the system.
 
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I've worked at dealers in Portland, SLC, and Denver and they all did it. Sometimes california dealers are lighter on the Maintenance because the weather isn't as extreme. I just looked in the Maintenance recommendations from the factory and 02 didn't list anything but, 04 updated and lists AHC replacement every 60k. I can e-mail you the pdf if you want. :D
 

CTapia

 
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LEXUSBEN said:
I've worked at dealers in Portland, SLC, and Denver and they all did it. Sometimes california dealers are lighter on the Maintenance because the weather isn't as extreme. I just looked in the Maintenance recommendations from the factory and 02 didn't list anything but, 04 updated and lists AHC replacement every 60k. I can e-mail you the pdf if you want. :D
I'll take a copy of the PDF, I'll P.M you my e-mail address.
 

tabraha

Hello My Name is: TAD
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So who's got the pdf? Somebody shoot it to me and I'll attempt to host it.
PM me so I can shoot someone an email address.
 

NMuzj100

 
 
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Landpimp in another thread said:
Toyota has the AHC fluid, part # 08886-01805, $21 for 2.5ltrs. in stock at my dealer. not sure if its cheaper then lexus...but it can't be anymore.
I'm sure Cdan can deal in this stuff now that Toyota has the AHC on the new models.
 

uHu

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tnx to lexusben, hoser & tad for the AHC fluid procedure, it looks like i will need it.

But what about the fluid in the shock absorber, and in the pipe leading to it?
I guess that liquid could need replacement as well. And it would probably take years for it to naturally mix with the rest of the fluid.

It looks like I have a serious issue with wrong fluid in the system. Needed a top-up three years ago, and again earlier this year, was told by toyo-dealer to use brake fluid.... dot4 - not dot5....
Over time this liquid has worked it's way down to where it is actually doing some work, with the result of no shock absorber effect, because that fluid is too "spongy".
Now, if I only change the fluid in the tank, and down to the bleeder plugs, I presume the ride would be just as spongy afterwords, because only the oil beyond that point actually carry the weight of the vehicle. Would I have to drain the shocks themselves? Is there much of the fluid inside them? And I guess I could drain the pipes between the Damping Actuators and the shocks, but would there be a problem of air inside afterwards...? What else...?

Any comments?
 
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