BradTank

My wife's 04 GX deflates sometimes when we park it, you can clearly hear a loud "whooshing" noise occasionally when we park it in our garage. The rear then goes to the lowest possible setting, it looks odd laying that low. Because it's not my car, I don't know if it always did that, but it seems "new" to me.

The deflation sound is coming from the rear mounted compressor on the rear driver side, I went under the car to investigate. It also appears that the air bags themselves aren't leaking, I raised the car to the highest setting, and it stayed there without the compressor kicking on or any leaking noise.

My guess is maybe the sensors need to be replaced, the thing is, I don't want to "shotgun" parts at a problem and spend $500 or so dollars on new sensors to experiment.

How do I know the rear is behaving correctly?

Any advice would be appreciated.

diagtime

almost always the air bags. they get dry rotted and only leak at certain heights. it not leaking down on high
makes sense for leaking air bags. we always replace them in pairs. spray soap water(or degreaser, windex, etc.) on them on normal or low level and see if you see bubbles.

we always replace both even if just 1 is leaking. the other one will go out soon and it's hard on the compressor.

Johnny Rad

Mine frequently whooshes a bit when i turn the truck off and get out. It doesn't go all the way to the bottom. I think it's just recalibrating "level" without the weight of the driver and or passenger.

diagtime

sometimes if one air bag is leaking the other one supports it enough to make the vehicle not lean. amazingly, it's hard to tell.

Booyah

When you turn it off they will deflate--mine does it every time, normal ops!!

diagtime

he said it goes down to the lowest level and looks odd there. the only reason they deflate when you get out of the car is because you are now out of the car and the suspension goes up due to less weight. it will then only lower it to the normal level. not low.

i bet she rides quite bouncy too at times.

BradTank

The odd thing is, the deflation is clearly coming from the rear compressor, there is a loud "whooshing" noise that's unmistakably coming from that point. I jacked up the car and removed the small access panel, the whole time I just thought it was the bags themselves. Is that normal? Could it be a sensor or valve that's "telling" it to deflate at the compressor?


What is your opinion on the aftermarket bags?:
http://www.ebay.com/itm/Rear-Air-Rid...sories&vxp=mtr

I know the first reaction is, "Lexus OEM is better" but honestly, I'm not too impressed with the quality of these factory bags, the car has never been towed or off roaded, and I'm looking at around a thousand dollars to replace them at the dealer. And then I'm probably going to have to replace the rear controlled shocks as well, it's looking like a $2,500 repair for an upgraded feature 99% of owners probably care nothing about.

I may also go with a steel coil conversion kit, the problem is, almost all of them have to be modified.

RCsGX

Its normal for the GX to lower some when you get out of the truck / shutting it down but it shouldnt lower to the lowest setting. Something is definitely not right. If I were you Id take it to Toyota / Lexus and have them look it over and find out 100% before you start throwing money at it.

BradTank

When I took it to the Lexus dealership, they said it needed new airbags (only after I asked them to look at the airbags). But I'm skeptical, I've had incidents at shops where any problem is basically diagnosed as needing the most expensive repair. In the past, I had a rear suspension noise diagnosed as needing a $1,200 repair when it ended up being a $25 bushing that I had to figure out myself.

If I could hear (or see) the airbags "leaking" air it would be a no brainer, but I have yet to hear or see that. The deflation noise is clearly coming from the compressor assembly. Also, the problem is intermittent. I would think a leak in an airbag would always be leaking.

I think the next step is going to be putting some soapy water on the airbags. The only issue is, the boot covering them makes inspecting them difficult.

diagtime

go with the soapy water. yeah the boots are annoying but they usually leak towards the bottom anyways. try the leak test on all three height settings.

It's possible to have a compressor issue, but not anywhere close to as common as the bags. it's possible the
noise you hear coming from the compressor is the normal noise but then the bags are leaking afterwards.

do not replace the shocks unless you really need them. they are expensive. you don't need them until they are either covered with oil or covered with dirt that's accumulated on the oil that leaked out.

let us know how the soapy water test goes

mann777

Brad to check your symptom, All you need is to test drive and do the roll motion,if there is excessive roll on either side by the test drives - perhaps you are the best judge to taht, that side the solenoid accumulator valve is defective Normally you could start by bleeding the air and replacing the AHC fluid. If this works good, others wise is a sure gonna be a replacement.

From What I see you symptom is just normal the hissing noise, or maybe a Air bleeding is a bit excessive
1. Get to a plain flat surface park your car,
2. ( Ignition off ) Stabilize the suspension by pushing up and down the corners of your truck
3. Start the Ingnition Parking Brakes Released. Place the Shift lever to "N" and settle the tires by moving the truck back and forthe by hand,
4. On the Height Control S/W press HIGH to raise the truck height, and then change the switch to LOW to lower it and continue this operation for 2-3 minutes. ( Never get in or out of the car)
You will observe that when the compressor starts to kick in to reach the high position it takes 25-45 seconds and gains a height of 1.55 inches and when the truck is in low position there is a reduction of 0.79 inches.
Ensure the Height Control S/W to off,
If there is a slight difference to above measurements then should be "GO"

If not then you have two issues here One is you need to jack the car on the frame and adjust using the height control Sensor Link along the slotted bracket. Also check the thread lock nut difference between both the wheels or could be air bleed leak and do the check via the soapy water to check for leaks among the tubes.

BradTank

Thanks for the feedback.

What is AHC fluid? I just assumed the entire height control system was pneumatic.

The system seems to work properly when I raise it and lower it (although I honestly NEVER use this silly system) it's just that sometimes when I park it, it goes down to the absolute lowest position, and when it lowers itself, the air is clearly coming from the compressor. As if some sensor is "telling" the compressor to deflate the system.

My fear is, the dealership is being lazy on it's diagnosis, I pay a thousand dollars to replace the air bags and they later concede it was some sensor or valve and then they want another thousand.

If I can't figure it out, I'm probably just going to drive as is before I just start throwing thousands of dollars at guesses. The car rides smooth and no error messages are coming up.

diagtime

I didn't respond to the AHC fluid post because i don't feel like arguing .....but you don't have any AHC fluid. that's for the LX470.

if there was a height control issue (which is always possible)......it would be on the low position while you are driving. did you check for leaks on the airbags with some kind of cleaner or soap water??? believe i already posted on how to do that.

The compressor will let out some air when you park it.....but it won't lower it very much at all. not to the lowest setting. Does it pump it back up significantly when you start the truck in the morning?

chrisvr6

Mine for example leaks overnight. I know so because in the morning i hit the button to lower the rear and the light on dash only blinks twice before it hits the lowest point. Should take longer than that.

diagtime

just spray some soapy water or degreaser or even windex on the airbags. especially at the bottom. watch for bubbles