avhart

Hi everyone

Can anybody (Yamae?) tell me how to adjust the rear height control valve / relief valve in my '93 LS400?

I think it may be causing the rear of my car to drop after it sits for a while - however if before I shut off the engine I put the suspension into "HIGH" it stays up just fine. Please note I realize I may be wrong in thinking it has to do with the control vale relief valve...

Any help would be appreciated

timmy0tool

iTrader: (7)

you could very well have a leak in the system altogether as the factory air suspension is very old and prone to it.
I'm fairly sure even if you leave the setting to "high" that the car will eventually squat over time as well proving certain a leak.

the car has height sensors on the suspension arms to feedback to the air controller. to the best of my knowledge there is no valve to adjust, only the height sensors.
I would not touch the sensors as it will only compensate for the leak masking the actual problem.

avhart

Hi Timmy, thanks for your response and willingness to help me out. I am pretty darn certain that once the suspension is on HIGH the car will not go down in the rear and therin lies my confusion.

I'm shooting arrows in the air here because this thing has me stumped. I can't hear a leak in the shocks so it all has led me to that no.2 height control valve in the trunk. That there is a leak I'm pretty sure but where to find it! I am suspecting the relief valve in the height control because I know i have messed with it at one time.

Kamakaze12

hi did you find any solution for the above mentioned issue, because i am experiencing the same. My height would stay up in hi position and engine left off.
but going very low on one side when put jn normal height mode.
please help.
i am even thinking about ditching air suspension, which is heart breaking for me.

avhart

Hey there, the answer I have to your question is a qualified yes. First off I disassembled the rear Height Control Valve and found not one but two, damaged o-rings which I replaced. This helped for a while but then it started to happen once again. Endless experimentation and troubleshooting thereafter has led me to the only remaining component - that darn shock!

Since you are experiencing much the same problem as I have I fear that is where it is leading. It doesn't bother me anymore because other than the embarrassment of how it looks in my garage, once I start it up the shock inflates and everything works fine until I park it up for a few days and the same thing happens. The only way to solve it would be to buy another used or refurbished shock (or new, if you can afford it) but I am not going to spend that money for what I now consider to be a minor inconvenience..

In response to your final comment of getting rid of the air suspension system altogether, that's a big fat NO! I am going to preserve the air ride for as long as I own the car. I have already replaced three shocks with used ones over the years and will continue to do so if and when necessary, although sometimes it takes a while until I accumulate enough money. No problem for me. I have another car that I use while the Lexus is down.

As a matter of fact it's down as we speak while I am repairing the power steering rack.

Please don't hesitate to ask me anything else you would like to know as I now have a good deal of experience with that model.

deanshark

The symptoms you have is a leaking shock which is a very common problem, due to age. It happened to mine, and many others. Once one goes, if you replace it, count on another one going very soon after, as "avhart" and many others have found out. I used to love my air suspension in my 93, until it broke and I saw how much it would cost to start replacing shocks, compressor, actuators, etc.etc. Most people are smart and ditched the air suspension.