Bouncy AHC! (1 Viewer)

[Rick Kane]

New to the forum and looking to tap into all of your generous advice and expertise! I’ve got a 2006 Land Cruiser with 112K miles on it, purchased in 2013. Vehicle has been great except for AHC issues. Took it down to Ecuador with me for a few years and in 2015 the front end just dropped when parked and the AHC would continuously raise it back up when stopped in traffic. Had a friend take it to the shop, where it appears in hindsight they must have placed brake fluid in the system! In 2016, now back in the U.S., one of the front globes failed (probably due to the brake fluid) - dumping suspension fluid all over the ground. I took it to the local garage for repair. Looking back now it appears that they used the “blind squirrel looking for a nut” diagnosis method Paddo describes on the “AHC Virgin” thread from 2018. First they replaced the front globes with brand new globes, flushed and replaced the AHC suspension fluid, and told me to “see how it goes.” The ride was bouncy and I returned it whereupon they changed out the rear globes, replacing the AHC fluid once again. That seemed to fix the issues for about 2 ½ years - until several months ago when the ride became extremely bouncy again. I can raise and lower the vehicle no problem – it’s just a really bouncy ride. Here’s my favorite part of the story so far – I took it back to the local garage and they just gave up on it, saying, “yeah, it’s bouncy, but we don’t know what to do with it.” So here I am thinking, “I could do this better myself.” I’ve ordered the iCarSoft TYTII and am ready to carry out “Paddo’s AHC Fluid Replacement Method.” I’ve done the height check test, however, and it appears to be just on the edge of passing the “7 graduations” minimum limit apparently determining whether I should go forward with an AHC fluid replacement or not (or if it’s more serious). Another issue I have is that I can barely see the AHC fluid level through the reservoir plastic as it is and have to shine a flashlight through the side and shake it to get a clue – what’s up with that? Any advice on where I should start to address my bouncy AHC issue would be most appreciated!

 

[LXG8R]

You have got to get the pressures. Without that you will be guessing.

 

[Rick Kane]

You have got to get the pressures. Without that you will be guessing.

Thank you LXG8R. Just received my iCarSoft TYTII today and took the readings multiple times after going from L to N.

- FR Height Control Sensor: -6.80 mm
- FL Height Control Sensor: -3.20 mm
- RR Height Control Sensor: -10.80 mm
- Front Pressure Sensor: 7.50 Mpa-g
- Rear Pressure Sensor: 6.60 Mpa-g
- Accumulator Pressure Sensor: 10.40 Mpa-g

I'll do some more reading here to see if those are readings are good news or bad.

Next planned course of action is do the AHC fluid exchange per Paddo's instructions and see if that doesn't help things.

 

[trdcorolla]

Don't forget to be on level ground and have a full tank of gas when you check pressure's.

 

[bentonrover]

Pressures are terrible. Crank the torsion bars and recheck pressures

 

[uHu]

I know first hand that brake fluid will eat the globes. If you are changing the globes again, make sure you get ALL the old fluid out, including what is hidden away in the shocks. That means taking the shocks off, drain them, fillem up with new fluid and rinse. Make sure you change all the old fluid, from the reservoir and all the way down to the shocks and globes, including what's inside the cylindrical accumulator. You'll have to put a bit of fluid through the system and work it up and down so that the accumulator pressure is used a couple of times.

And yes, get the pressures and heights right as well. Plenty of info on this in other threads.

 

[eurodre]

if you find yourself needing any ahc parts, I just took mine off of my LX470 with 135k miles.

best of luck!

 

[Rick Kane]

I know first hand that brake fluid will eat the globes. If you are changing the globes again, make sure you get ALL the old fluid out, including what is hidden away in the shocks. That means taking the shocks off, drain them, fillem up with new fluid and rinse. Make sure you change all the old fluid, from the reservoir and all the way down to the shocks and globes, including what's inside the cylindrical accumulator. You'll have to put a bit of fluid through the system and work it up and down so that the accumulator pressure is used a couple of times.

And yes, get the pressures and heights right as well. Plenty of info on this in other threads.

I know first hand that brake fluid will eat the globes. If you are changing the globes again, make sure you get ALL the old fluid out, including what is hidden away in the shocks. That means taking the shocks off, drain them, fillem up with new fluid and rinse. Make sure you change all the old fluid, from the reservoir and all the way down to the shocks and globes, including what's inside the cylindrical accumulator. You'll have to put a bit of fluid through the system and work it up and down so that the accumulator pressure is used a couple of times.

And yes, get the pressures and heights right as well. Plenty of info on this in other threads.

Spoiler Alert: Bad News...

I performed Paddo's AHC fluid exchange.

First sign of trouble was that much of the old fluid was bubbly and frothy when I bled it out.

Then I got the pressures to the following by cranking the torsion bars:

- FR Height Control Sensor: -9.60 mm
- FL Height Control Sensor: 1.60 mm
- RR Height Control Sensor: -10.00 mm
- Front Pressure Sensor: 6.80 Mpa-g
- Rear Pressure Sensor: 6.70 Mpa-g
- Accumulator Pressure Sensor: 10.30 Mpa-g

With front pressure within the "acceptable" range I moved on to checking the graduations in the AHC reservoir going from Low to High. Not good - a difference of only 4 graduations. Indicator pointing to bad globes. Question was "which ones?"...

Moved on to the 16-point test of the globes - immediately found that the front globes were rock hard on Step 1. Rear globes performed fine throughout the test...

So it's pretty apparent that both front globes are shot.

Here are my questions:

- Given that all four globes were replaced within the last 3 years and even though the system was supposedly flushed twice (once when the two front globes were replaced, and again 4 months later when the two rear globes were replaced), is it even worth replacing just the two front globes - or should I go all the way and replace all four now?

- Like uHu says above, I clearly need to make sure all of the evil brake fluid is out of the system. Anybody have experience pulling the shocks off? Do I just jack up the cruiser and take them off one at a time, drain them, fill them up with new fluid and put them back on? I have yet to see a description of this procedure on the forum, but that doesn't mean it's not here...

- I used 2.5 liters of new fluid for the fluid exchange. How much will I need for a full system refresh, 5 liters?

Thanks all, the education continues...