Changing out the AHC suspension fluid? (6 Viewers)

[uHu]

Two options:
1
Rip off all AHC parts and change all four springs and shock absorbers to the standard LC type, or something better. I.e: Convert to conventional suspension (you can read pages and pages about it in here).

2
You can get 2nd hand spheres from a breaker or otherwise/elsewhere, from a damaged vehicle with a low milage (say under 100 k km). At the same time buy new coil springs and have the front TBs adjusted

Alt 1 is probably cheaper, particularly in the long run.
Consider that you will, at this age, have to change the coil springs of your AHC system anyhow, and remove and re-index the torsion bars.

With AHC, the next thing to go is the pump, or the sensors. I'm not advocating conversion to conventional suspension - I think the AHC is great, but be prepared for maintenance.

 

[xxxALFxxx]

I want to keep AHC suspension. I like that car is always in same level when you put heavy load in
I have other question Is it neccesary to bleed whole system when you want to change one gas sphere or bleed one corner is enough?
Thank you.

 

[uHu]

If your fluid doesn't need changing, I think you can get away with bleeding only that corner. Iirc there wasn't much air getting in when I changed spheres.

But don't you need four new spheres?

 

[xxxALFxxx]

Hello,
I bought 4 new spheres for 500 USD each. I did not want to buy used because they could be broken as mine.
I changed spheres and now I have 14 grads on reservoir between LOW and HIGH position. I never had so smooth ride before

 

[deezwild]

I have a customer that just brought their 07 LC to my shop with a "rough ride", next-to-no-travel condition with their vehicle. I haven't had any previous experiences with this system (thank god). I've read just about everything I could find on here about the system, but am still a little baffled... If the vehicle has a full 12 graduations from LO to HI and back, then wouldn't that mean the spheres are working correctly? The fluid level and graduation test are all fine, yet I still have very little travel on each corner. Does anyone knows what I'm up against here? Thanks for any educated input!

 

[agaisin]

I have a customer that just brought their 07 LC to my shop with a "rough ride", next-to-no-travel condition with their vehicle. I haven't had any previous experiences with this system (thank god). I've read just about everything I could find on here about the system, but am still a little baffled... If the vehicle has a full 12 graduations from LO to HI and back, then wouldn't that mean the spheres are working correctly? The fluid level and graduation test are all fine, yet I still have very little travel on each corner. Does anyone knows what I'm up against here? Thanks for any educated input!

You really want the FSM - it has tons of diagnostic information.

I'm assuming you have already tried adjusting the damping from sport to comfort?

You should probably check for AHC DTC codes (either need techstream/handheld tester or using a jumper to connect pins TC and E1 on DLC1 and then reading the # of times the AHC Off light blinks).

There is also a procedure in the FSM for diagnosing/testing the damping force actuators to verify that with each of 16 increments of the actuator positions you can feel the 'shock absorber' get harder.

Some thoughts:

- Checking for DTC codes should probably be your first order of business.

- Check for correct vehicle height (according to the manual, not just by comparing floor to fender heights). Is something out of whack there?

- Check neutral pressure on front and rear. Is it within spec (note that you can either use handheld tester or LSPV gauge - the pressure specs you're looking for will be different depending on which approach you use so don't get confused there).

- Failed globes are a good guess based on the symptom. However as you know, according to the FSM you can test condition of the accumulator globes by checking for > 7 gradations in the reservoir. I have heard that it's possible to 'pass' this test even if the globes are failed - I don't know if that's true or BS. Some suggest just taking off the globes to see if they're ruptured.

- It is possible that the fluid is in horrid condition (or even the wrong fluid). TexasOil has recently posted a test to verify that you have the correct fluild. If the fluid looks dirty and hasn't been changed in 50k or more, I would suggest flushing it. It's easy and cheap compared to all the other options.

- If fluid flush doesn't solve anything, test the damping switch (comfort, normal, sport1, sport2). Is that broken? I think I have seen people report they needed to replace that, or removed it and didn't connect it back properly).

- If the switch operates correctly, globes appear in great condition, height of vehicle is correct, pressure up front and rear is correct, then you've probably got a more difficult problem on your hands.

- If all else fails, throw parts at the problem

 

[deezwild]

Thanks agaisin for the quick reply. As you know, in a shop, time is money..... Do you know, or have access to, the procedure for testing the damping switch? That's exactly where my first thoughts lie, as I feel NO difference between the different selector points on this switch, nor hear any clicks, actuator noises, etc. I hope it does lie in this switch, as I have a hard time believing it's the spheres when I'm getting a full 12-point graduation at the reservoir, with no leakdown. They seem to be functioning exactly as I would expect them to, and with a very strong ride height change. This leads me to believe that whatever is controlling the pressures/oil levels/travel length in the shock absorbers themselves would be the culprit... Any procedures related to this that you have any info on would be greatly appreciated Great post BTW!

 

[Texasoil]

the 'gas springs' or accumulators (actuators in Toyota speak) are dead. Check for contamination using the Water Reaction Test (below) as even small amounts of most common contaminants will destroy the diaphragms in the 4 wheel accumulators.


B and B Suspension LLC
AHC FLUID WATER REACTION TEST
1) Purpose;
AHC fluid is very light colored highly refined low viscosity petroleum oil. Its appearance is (prior to new fluid from 2009 on) light greenish to light straw colored, clear and transparent. New fluid sold from 2009 on is dyed a light red/pink in color to distinguish it from other products. The similarity in appearance to brake fluid, many windshield cleaner concentrates, and un-dyed ethylene glycol antifreeze concentrate has contributed to many instances of service personnel using these similar appearing fluids to top-off or refill the AHC fluid reservoir. Unfortunately, the ‘new color’ is nearly identical to that of ‘environmentally safe, non-toxic or RV water system antifreeze—propylene glycol) All of these common contaminating fluids are very detrimental to the ‘rubber’ components in the AHC system.

The diaphragms separating AHC fluid from high pressure Argon in B&B Suspension accumulators are made from a special ‘Nitrile’ compound formulated to retain flexibility and strength from -40 to + 180 F. These parts flex with every tiny bump and road roughness and thus are repeatedly stressed where they bend. The common contaminants mentioned above are VERY DETRIMENTAL to the diaphragm because they dramatically increase cracking from repeated flexing. Even very low contamination levels, barely detectable by this rough test, can reduce accumulator life by 75% or more.

This ‘Water Reaction Test’ is designed to quickly show if any significant amount of brake fluid, methanol, propylene or ethylene glycol are present in the AHC fluid where an accumulator failed unexpectedly. Note this contamination may have caused failure of the original accumulators before the present owner acquired the vehicle. Many Owners have experienced repeated failures of Dealer installed OEM accumulators following known system contamination and accumulator failure, even though ‘the system was flushed with new AHC FLUID EACH TIME.’ Draining the reservoir and refilling with fresh AHC oil, then flushing to the accumulator bleed screws leaves nearly 75% of the old oil and contamination in the struts and main pressure accumulators.

2) Test Procedure;
Prepare 3 glass pint jars with lids by thoroughly washing with detergent and then thoroughly rinsing to ensure all detergent residue is removed . Ideally the final rinse should be with distilled water. From the right front accumulator bleeder, catch approximately 4 ounces of the old AHC oil into one of the clean glass pint jars—BEFORE ANY ACCUMULATORS OR FLUID ARE REMOVED. Then into another clean jar, catch a similar 4 ounce sample from the right rear bleeder. Add two (2) ounces of distilled water to each jar with the samples. Cap and then vigorously shake both jars for thirty (30) seconds to thoroughly mix the oil and water and then place the jars on a flat stable surface and allow them to sit and settle. After they have settled for 30 seconds, take color photographs of each bottle, then again after 2 minutes , and again after 5 minutes. Take the photos close enough to clearly show the interface between oil and water layers. EMAIL all 6 photos to kebowers47@gmail.com and kvnedbow@gmail.com. Note: Depending on the vigorousness of the shaking, a very fine emulsion may form which may take several hours to fully separate, even for the new fluid. However, even very fine emulsions of uncontaminated fluid and water will show growing clear layers within 5 minutes.

 

[agaisin]

the 'gas springs' or accumulators (actuators in Toyota speak) are dead. Check for contamination using the Water Reaction Test (below) as even small amounts of most common contaminants will destroy the diaphragms in the 4 wheel accumulators.

Keith, this raises a question that's come up a number of times on the forum - how can you 'pass' the reservoir test (12 gradations) with flying colors and have failed accumulators?

 

[uHu]

the 'gas springs' or accumulators (actuators in Toyota speak) are dead. Check for contamination using the Water Reaction Test (below) as even small amounts of most common contaminants will destroy the diaphragms in the 4 wheel accumulators.

The accumulators are called "gas chambers" in Toyota lingo.
Actuator is the valve body that the accumulator is screwed on to. The valves in the actuators perform the damping, the shock absorber function.

 

[deezwild]

Keith, this raises a question that's come up a number of times on the forum - how can you 'pass' the reservoir test (12 gradations) with flying colors and have failed accumulators?

*hears crickets....*

Ironic, this must be one life's unanswerable questions? LOL

 

[kapil]

dear all , i recently bleeded the accumulator with all the ahc fluid and replaced it with the original toyota suspension fluid , the fluid that came out of the accumulators was white foamy liquid. however even after using 2 jericans 2.5 litres of the fluid the liquid that comes out is still foamy and the front shocks are like as if they don't exist. its a very very bumpy ride . please help.

 

[PLROD]

the 'gas springs' or accumulators (actuators in Toyota speak) are dead. Check for contamination using the Water Reaction Test (below) as even small amounts of most common contaminants will destroy the diaphragms in the 4 wheel accumulators.


B and B Suspension LLC
AHC FLUID WATER REACTION TEST
1) Purpose;
AHC fluid is very light colored highly refined low viscosity petroleum oil. Its appearance is (prior to new fluid from 2009 on) light greenish to light straw colored, clear and transparent. New fluid sold from 2009 on is dyed a light red/pink in color to distinguish it from other products. The similarity in appearance to brake fluid, many windshield cleaner concentrates, and un-dyed ethylene glycol antifreeze concentrate has contributed to many instances of service personnel using these similar appearing fluids to top-off or refill the AHC fluid reservoir. Unfortunately, the ‘new color’ is nearly identical to that of ‘environmentally safe, non-toxic or RV water system antifreeze—propylene glycol) All of these common contaminating fluids are very detrimental to the ‘rubber’ components in the AHC system.

The diaphragms separating AHC fluid from high pressure Argon in B&B Suspension accumulators are made from a special ‘Nitrile’ compound formulated to retain flexibility and strength from -40 to + 180 F. These parts flex with every tiny bump and road roughness and thus are repeatedly stressed where they bend. The common contaminants mentioned above are VERY DETRIMENTAL to the diaphragm because they dramatically increase cracking from repeated flexing. Even very low contamination levels, barely detectable by this rough test, can reduce accumulator life by 75% or more.

This ‘Water Reaction Test’ is designed to quickly show if any significant amount of brake fluid, methanol, propylene or ethylene glycol are present in the AHC fluid where an accumulator failed unexpectedly. Note this contamination may have caused failure of the original accumulators before the present owner acquired the vehicle. Many Owners have experienced repeated failures of Dealer installed OEM accumulators following known system contamination and accumulator failure, even though ‘the system was flushed with new AHC FLUID EACH TIME.’ Draining the reservoir and refilling with fresh AHC oil, then flushing to the accumulator bleed screws leaves nearly 75% of the old oil and contamination in the struts and main pressure accumulators.

2) Test Procedure;
Prepare 3 glass pint jars with lids by thoroughly washing with detergent and then thoroughly rinsing to ensure all detergent residue is removed . Ideally the final rinse should be with distilled water. From the right front accumulator bleeder, catch approximately 4 ounces of the old AHC oil into one of the clean glass pint jars—BEFORE ANY ACCUMULATORS OR FLUID ARE REMOVED. Then into another clean jar, catch a similar 4 ounce sample from the right rear bleeder. Add two (2) ounces of distilled water to each jar with the samples. Cap and then vigorously shake both jars for thirty (30) seconds to thoroughly mix the oil and water and then place the jars on a flat stable surface and allow them to sit and settle. After they have settled for 30 seconds, take color photographs of each bottle, then again after 2 minutes , and again after 5 minutes. Take the photos close enough to clearly show the interface between oil and water layers. EMAIL all 6 photos to kebowers47@gmail.com and kvnedbow@gmail.com. Note: Depending on the vigorousness of the shaking, a very fine emulsion may form which may take several hours to fully separate, even for the new fluid. However, even very fine emulsions of uncontaminated fluid and water will show growing clear layers within 5 minutes.

Hello Keith, I've been trying to contact you in attempt to find out when you are going to send me the 4 replacement spheres you indicated said you were going to send me on 11/18/16. At this point I cannot use my car until I resolve this issue. Please respond - I've left you multiple voice messages and emails at this point.

 

[PADDO]

@PLROD, the user you're after was last seen here in Jan 2014. Good luck with your system, obtaining inexpensive serviceable OE takeoff accumulators might be worth following up as there are plenty out there. What's the general state and health of your system, was it contaminated?

 

[Dannyboy lx470]

Guys just a question when you use the shock switch from comfort to sport for a different ride do you hear a noise when switching and how would describe the difference in settings I'm new to the car trying work out if it works.


Is all the toyota suspension fluid red.Cause the one here I seen them put more like light yellow and green and it is genuinen toyota one.

 

[PADDO]

There is no noise associated with changing comfort modes other than the click of the switch. If you need to ask what the different settings feel like then that immediately suggests your system isn't performing as designed - basically position 1 feels somewhat under damped with a "floaty" feel; 2 should feel more normal and stable; 3 more firm and very little body roll (I use position 3 for the most part ) and 4 is a very firm and solid ride that many would describe as a bit too hard and over damped for daily driving unless you like 6000lb sports cars. I like 4 for highway driving.
Ensure your AHC fluid has/is changed at no more than the recommended service intervals and there is no entrapped gases in the system, or better yet do a fluid exchange/bleeding if you don't know the accurate AHC service history.
Search and find the description of the 16 step test so you can put your vehicle through the dampening settings manually and get a feel for what the differences are. You'll also need a method of reading your neutral pressures as they are the lifeblood of dampening performance and do the L to H graduation check for a quick collective damper accumulator health check.

 

[Dannyboy lx470]

Ok thankyou for that.

There is no noise associated with changing comfort modes other than the click of the switch. If you need to ask what the different settings feel like then that immediately suggests your system isn't performing as designed - basically position 1 feels somewhat under damped with a "floaty" feel; 2 should feel more normal and stable; 3 more firm and very little body roll (I use position 3 for the most part ) and 4 is a very firm and solid ride that many would describe as a bit too hard and over damped for daily driving unless you like 6000lb sports cars. I like 4 for highway driving.
Ensure your AHC fluid has/is changed at no more than the recommended service intervals and there is no entrapped gases in the system, or better yet do a fluid exchange/bleeding if you don't know the accurate AHC service history.
Search and find the description of the 16 step test so you can put your vehicle through the dampening settings manually and get a feel for what the differences are. You'll also need a method of reading your neutral pressures as they are the lifeblood of dampening performance and do the L to H graduation check for a quick collective damper accumulator health check.

Thankyou.That sounds interesting the L to H check to test the damper accumulator.If any one has the lonk to both these test please post them.

 

[hagani]

There is no noise associated with changing comfort modes other than the click of the switch. If you need to ask what the different settings feel like then that immediately suggests your system isn't performing as designed - basically position 1 feels somewhat under damped with a "floaty" feel; 2 should feel more normal and stable; 3 more firm and very little body roll (I use position 3 for the most part ) and 4 is a very firm and solid ride that many would describe as a bit too hard and over damped for daily driving unless you like 6000lb sports cars. I like 4 for highway driving.
Ensure your AHC fluid has/is changed at no more than the recommended service intervals and there is no entrapped gases in the system, or better yet do a fluid exchange/bleeding if you don't know the accurate AHC service history.
Search and find the description of the 16 step test so you can put your vehicle through the dampening settings manually and get a feel for what the differences are. You'll also need a method of reading your neutral pressures as they are the lifeblood of dampening performance and do the L to H graduation check for a quick collective damper accumulator health check.

@PADDO

I have red some posts where it says that with the flush of the system 5-%-75% of old fluid stays in the system (i.e. in shock and spheres). Do you think using an extractor like the one on the picture connected to the bleeders will help extract if not all but most of the fluid?

 

[PADDO]

No need to try and use an extractor, if you follow my one can bleed method and drop the front and rear to the bump stops and bleed the height accumulator without restarting the vehicle you'll remove about 1 liter of fluid (take out the other liter+ from the reservoir) and you'll get most of the fluid out of the system. That 50-75% number may have come from me a while back (based in the old start/stop/bleed/start/stop process). I've since carefully measured the capacities of components and how much fluid is expelled when you drop to the bumps and am satisfied you can get the majority of old fluid out.

 

[hagani]

No need to try and use an extractor, if you follow my one can bleed method and drop the front and rear to the bump stops and bleed the height accumulator without restarting the vehicle you'll remove about 1 liter of fluid (take out the other liter+ from the reservoir) and you'll get most of the fluid out of the system. That 50-75% number may have come from me a while back (based in the old start/stop/bleed/start/stop process). I've since carefully measured the capacities of components and how much fluid is expelled when you drop to the bumps and am satisfied you can get the majority of old fluid out.

@PADDO

If I have only 4 gradations on the reservoir test any chance it could be due to the contaminated fluid? Or don't bother and just go ahead with ordering new spheres? I have already adjusted TB and still can't get the pressure down..

Please check this:

https://forum.ih8mud.com/attachments/img_0002-jpg.1373716/

and this:

First Bought a UZJ100: 1998 LX470, 198K mi. Failed AHC. Suspension Advice Needed.