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Pneumatic Height Control???


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21 replies to this topic

#1 KNIGHTRIDER

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Posted 27 November 2005 - 10:59 PM

Hey everyone. I have a 1987 Subaru GL-10 4WD Turbo Wagon with pneumatic height control. It's working fine. I have heard that it is basically electronic suspension. What I wanted to know, if its normal for the car to be down after not using it for a couple of days and it returning to normal after using it.

Thanks,

KNIGHT RIDER

#2 stumpy

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Posted 28 November 2005 - 12:13 AM

It's an electric/pneumatic system. An on board electric compressor supplys air to the struts. If it's lowering its self after setting for a few days you have a slow leak in the system some where.

#3 KNIGHTRIDER

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Posted 28 November 2005 - 12:21 AM

It's an electric/pneumatic system. An on board electric compressor supplys air to the struts. If it's lowering its self after setting for a few days you have a slow leak in the system some where.


Thanks for the reply. :) Where would I get it fixed or checked??? I hope its cheap and not extremely expensive? What should I do for future to maintain it???

Thanks,

KNIGHT RIDER

#4 [HTi]Johnson

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Posted 28 November 2005 - 12:24 AM

You could take the whole airbag system out...and replace it with struts from the same type of vehicle. That's what I did because mine weren't reliable and it makes for better handling.

#5 86subaru

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Posted 28 November 2005 - 06:18 AM

i took mine out also , put in adjustable front struts from a 85 wagon, took awhile to find some , , [ manual ] , i have been working on a 86 wagon and saw that it has rear manual adjustable struts also

#6 john in KY

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Posted 28 November 2005 - 06:40 AM

[quote name='KNIGHTRIDER']Hey everyone. I have a 1987 Subaru GL-10 4WD Turbo Wagon with pneumatic height control. It's working fine. I have heard that it is basically electronic suspension. What I wanted to know, if its normal for the car to be down after not using it for a couple of days and it returning to normal after using it.

Just as a test disconnect the battery for a few days. If the suspension remains up then you know the problem is not a leak somewhere in the system. I'm thinking the problem is a failing tank solenoid or tank pressure switch.

#7 grossgary

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Posted 28 November 2005 - 10:35 AM

good maintenance would be to replace all the o-rings at each strut and the compressor. the orings are nearly 20 years old and they basically crack when you remove them because they are old and brittle...doesn't make for a good seal. good luck finding a mechanic that knows what they are doing, these air suspensions are not very common and most people swap if they can to coil overs.

i also posted a thread about conditioning your struts so they last. on the XT6 new air struts run $400 from subaru...a little cheaper with some on line searching and are hard to come by at times.

here's a write up i did on keeping your struts from wearing out:
http://xt6.net/forum...light=air strut

i have found that letting an air suspension vehicle sit without running for a week or more does not do it any favors...i think the valve in the compressor builds corrosion or already existing corrosion gets worse. i've had a number of XT6's that had perfectly working air suspensions turn flaky after taking them off the road for a week to a couple months for timing belts or engine replacement.

if it's lowering at all then yes it's loosing air somewhere. i parked an XT Turbo a month or two ago and it's still riding high and i haven't turned it on...actually it doesn't even have a battery yet.

#8 Subarian

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Posted 28 November 2005 - 11:21 AM

In response to your original question, it's not the same as electronic ride control. Its purpose is to allow you to raise or lower the car from the inside by means of a pneumatic system. But it doesn't have sensors that adjust to road conditions like electronic ride control does.

I used to have one, and the ritual every morning was to start the car and then wait for it to raise itself before I took off.

#9 grossgary

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Posted 28 November 2005 - 11:30 AM

pretty sure the FSM for the XT6 details changes that occur based on driving conditions/speed. surely very minor, but it does something. certainly not performance enhancing.

#10 Subarian

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Posted 28 November 2005 - 11:33 AM

You're right about that. It does automatically lower ride height above a certain speed, but I can't remember what that speed is.

#11 stumpy

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Posted 28 November 2005 - 12:21 PM

As long as it keeps pumping its self up when you use it I wouldn't worry about it until summer when it would be more comfortable to work on it. I would check it out to see if it's a cheap fix before deciding what my course of action is! The pneumatic suspension is nice when it's working properly. When old age sets in it can become problematic and expensive to maintain. It becomes cheaper and less of a hassle to convert to standard struts.

#12 KNIGHTRIDER

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Posted 28 November 2005 - 02:08 PM

Thanks you all for responding quickly. Is there a sure way of knowing what's wrong, like a test or something?? Or can you get it checked??? Would I have to take it to a mechanic or a Subaru Dealer?? Thanks, I just wanted to know where should I start first.


KNIGHT RIDER

#13 john in KY

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Posted 28 November 2005 - 05:34 PM

From your description it sounds like all 4 struts go down. If this is true then it means all 4 struts have a slow leak or the air lines between the front struts are leaking or all 4 strut solenoids are leaking or some combination of the aforementioned. This is very unlikely.

The compressor is designed/wired to kick in even if there is no key in the ignition. The only way the compressor and solenoids can be taken offline is to disconnect the battery. This is why I suggested in a previous posting to disconnect the battery and let the car sit for a couple of days.

If you do this test and the struts stay inflated you then know there is no leakage in the system. If one or more struts deflate but not all you now know those struts have a leakage problem.

I suspect if you do this none of the struts will deflate. This means tank solenoid or control unit problems most likely.

Attempting to diagnose the problem without the FSM will be very difficult. If the system stays up with the battery disconnected I would just disconnect the battery whenever you planned on not using the car for a few days.

#14 KNIGHTRIDER

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Posted 28 November 2005 - 09:19 PM

From your description it sounds like all 4 struts go down. If this is true then it means all 4 struts have a slow leak or the air lines between the front struts are leaking or all 4 strut solenoids are leaking or some combination of the aforementioned. This is very unlikely.

The compressor is designed/wired to kick in even if there is no key in the ignition. The only way the compressor and solenoids can be taken offline is to disconnect the battery. This is why I suggested in a previous posting to disconnect the battery and let the car sit for a couple of days.

If you do this test and the struts stay inflated you then know there is no leakage in the system. If one or more struts deflate but not all you now know those struts have a leakage problem.

I suspect if you do this none of the struts will deflate. This means tank solenoid or control unit problems most likely.

Attempting to diagnose the problem without the FSM will be very difficult. If the system stays up with the battery disconnected I would just disconnect the battery whenever you planned on not using the car for a few days.


Thanks John. . . I didn't clarify it but only the back portion of the car goes down, the front is fine . . . As long as I use the car regularly it doesn't happen, but let's just say if I didn't use it for two or more days the back portion of the car would be down. I will try the whole battery thing, but I hope it's nothing major.

Thanks,

KNIGHT RIDER

#15 john in KY

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Posted 28 November 2005 - 09:37 PM

An XT6 I bought a couple of years ago with almost new rear struts did exactly the same thing. Leave it parked and within minutes the rear solenoids would open and dump the compressed air. Start the engine and the struts immediately would inflate. I eventually "solved" the problem by replacing the control unit under the seat. Haven't had a lick of suspension problems in the last 2 years.

#16 KNIGHTRIDER

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Posted 28 November 2005 - 10:59 PM

An XT6 I bought a couple of years ago with almost new rear struts did exactly the same thing. Leave it parked and within minutes the rear solenoids would open and dump the compressed air. Start the engine and the struts immediately would inflate. I eventually "solved" the problem by replacing the control unit under the seat. Haven't had a lick of suspension problems in the last 2 years.


Where would the control unit be in my Car??? 1987 Subaru GL-10 Turbo 4WD with Pneumatic Height Control

Thanks,

KNIGHT RIDER

#17 john in KY

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Posted 29 November 2005 - 06:42 AM

Don't know but in the XT/XT6 it is under the carpet under the driver's seat up against the sill. My guess it is in the same location for the GL10. Have to remove the seat and sill plate and then roll back the carpet to find it.

#18 Alex GL-10

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Posted 20 December 2005 - 10:43 PM

You're right about that. It does automatically lower ride height above a certain speed, but I can't remember what that speed is.


55mph

#19 grossgary

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Posted 20 December 2005 - 11:27 PM

having this system worked on anywhere would be costly. parts are hard to find and expensive and few people know anything about them. you will be hard pressed to find anyone knowledgeable to diagnose this system. i doubt even dealer mechanics would know anything and they're going to charge mad loot to diagnose and replace with new (parts are 200 dollars and up.....struts are 400 each from the dealer). add labor and you can easily get to $1,000 in no time.

if you're not working on it yourself and don't want to spend many hundreds of dollars and numberous visits you're best bet is to look towards converting. or use the board to diagnose as best as you can and buy used parts and have them swapped in. for instance buy a used computer and swap it in, buy a used compressor and swap it in.

if you're going to have it worked on, have all the o-rings replaced that are accessible - they are on the compressor and air tank under the fender and solenoids/struts elsewhere.

i've kept mine, but it's been interesting at times....

#20 ballitch

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Posted 21 December 2005 - 01:03 AM

the air suspension is one of the many subaru "guinea pig experiments" that eventually go wrong, usually age is the factor. i say get some new GR-2's from ebay for your car, unhook the air struts in the back and unplug the connectors, as long as the front still works, it shouldnt be a problem. or, if you can wait until spring or summer to fix it, just convert it to plain jane struts.




~Josh~

#21 NorthWet

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Posted 21 December 2005 - 01:16 PM

pretty sure the FSM for the XT6 details changes that occur based on driving conditions/speed. surely very minor, but it does something. certainly not performance enhancing.

On the EA82, if you have it in "High", it will automatically lower at freeway speed... 45 or 50mph, IIRC.

*EDIT - I must have missed GG's previous post when I wrote the following comment about o-rings. Lazy/blind me... :banghead: end edit *
I am surprised that Gary didn't mention the many o-rings in the system (at each connection) that tend to get old and leak. (Gary has helped me greatly with understanding what was wrong with the system on my wife's car. :) ) The o-rings are cheap and easy to replace... just a whole bunch of them.

Regarding metal vs. air springs: No contest for highway ride quality. The air springs are preeety nice. Really dampen road vibration and noise transmission.

#22 grossgary

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Posted 21 December 2005 - 08:39 PM

agreed, i really like the air-ride better than any coil overs i've driven in. im' sure with some effort a good spring/strut combination would provide excellent feel, but not with the coil overs i've done and driven in.

also agree on the orings, replace them all. lightly grease the new ones.
they are all the same size, but there is one on each rear strut that is a different size than the rest. they are "under" the solenoid when you unbolt the solenoid from the rear strut. other than those two, the rest are all the same. so size match the ones on the front solenoids (easiest to get to) and buy a couple dozen or so. 1/4" OD 1/8" ID i think.




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