Hello all! Question about the air suspension. I've searched already but...

[Layman]

I keep seeing people go straight to "you need to replace them". I don't believe this is always the case, and I'm wondering if anyone has figured out if there can be a module, or controller going on some of these. Here's what I know about my 1990 LS400: The rear end are the only ones to leak down. If they leak down to "bottom" I can unhook the positive battery cable for a while (hour?) and reconnect to resolve the issue. I hear the air only hissing out of the driver side wheel well when the car dumps. If I grab the fender and lift, or place a jack under the body in front of the rear driver's wheel, the hissing stops and it will begin to lift, but only for a short while. When I lift the car high enough, the hissing stops. This makes me think that I'm overcoming something like a valve/solenoid. When I disconnect/reconnect the positive terminal, it takes about 75-85 miles to dump again. This leads me to believe the bags are not leaking, but something that controls the fill is resetting, then failing. So, to sum it up;

1. Bags do not truly seem to leak (air bleed only on driver side, though both rears dump)
2. Resetting the electronics via battery disconnect resolves it temporarily (similar to a computer reset)
3. Air bleed occurs from the rear driver side area (perhaps the location of a solenoid/valve)
4. I can raise the rear driver side with a jack to overcome the bleed (as if there's a point where I've relieved the pressure that's keeping the valve open)

Anyone have a clue what to start working on to keep my air?

[Exhaustgases]

Your likely on to something, and I agree I would not jump into replacing the air with coils unless I needed super dependability for a long trip or something.

The ecu for the air is in the trunk on the right side. It could have leaking capacitor problems like the engine ecu does. There could also be a solenoid valve leaking as well.

I don't think all the leaking is from the bags themselves either. It could also be a height sensor not doing something right either but that should affect something all the time, I'd think.  Did you check for codes?  They are listed on the Lexls site I think its called.

[LSPaul]

From what you're describing, it IS the air bag.  I experienced the same sorts of things when I had an air ride LS...  When the rubber air bladder is cracked, it'll first fail when in normal ride height position, but will hold air when the suspension's in the high position.   Several years ago, I had good luck buying a re-man'ed air strut from Arnott for the '93 I owned at that time, but I don't think they offer rebuilt air struts for the LS any longer. 

The height sensors rarely fail, the electronics could be suspect (ECU caps), but most likely it's the air strut if you're hearing air leak.  

Changing the struts is actually easier than changing a convention rear spring/strut, BTW.  Still a pain, but slightly easier since the airbags compress easily when disconnected.  As for where to find another air strut, you're likely going to have to look on ebay, or check car-part.com.

Paul

 

 

[tar heel guy]

Unfortunately you'd have a really difficult time finding replacement air struts for your LS. 

For what it's worth some of the coil conversions ride pretty great and end the hassle you're going through.

[LSPaul]

This.  Especially on a first-gen car.  I haven't sampled many of the conversion kits other than the Strutmaster kit, which, while had a nice spring rate and ride characteristics, the ride height on their springs approximated that of the air suspension in the high position.   I'd probably look for OE springs and strut inserts.