[TxBuicks]

My 1991 Roadmaster Estate Wagon is in need of rear shocks. The car has the automatic leveling system in which an air compressor is attached to the rear shocks. It doesn't work. I can hear the air compressor switch on at times but nothing happens. I'm not sure at this point if there is a leak in the air lines or the shocks. I have never met an owner that said this system is still working on his car. All I ever read about is how these systems didn't work too well, even new. So my question is can I replace these air shocks with non-air shocks and just disconnect the air compressor? Or do I try to fix the system? I'd like to hear comments from those who are familiar with this.

Thanks in advance for your comments.

[acboxer]

Not sure about your system but I have a 1984 Olds 98 and 1985 Buick Rivera with the same type of system the air shocks due go bad but are a easy replacement and the air lines kit is a easy to find part at most parts store or if you find a leak in the plastic line due to touching a exhaust system pipe or due to rubbing a repair fitting is easy to find at your local parts store use a coupling. Also check the electrical connections for poor contact.
check to see if the link to the level switch is connected. The switch has a built in time delay to raise or lower car as load dictates. Not sure of 91 manual but the ones for my car make troubleshooting pretty easy.

[pfloro]

Hello TxBuicks:

I didn't know that GM made an 'electronic level control' system with the compressor mounted on the one of the rear shocks...

The system on my '84 Toronado has the compressor under the hood but I would guess the system is basically the same.

I would try to isolate the problem. It will either be in the 'air' side of the system or in the electrical/electronic side.

It's gonna be tough to do this without the car being raised by it's tires on a lift. If you can get the car up, power the compressor directly with 12 volts (this bypasses the height controller). There should be a single wire connected to the compressor motor (ignore the other wire pair which is for the vent solenoid). Remove it & apply 12V. The compressor should run and slowly raise the rear of the car. If the car doesn't rise, either the compresssor is defective or there is a leak in the system. It's possible that the air 'bladder' in one or both shocks is ruptured. If the car rises, remove power from the compressor and listen closely to it. Within several seconds, the vent solenoid valve should open, hissing should be heard and the car should lower. The 'ride height' control module will sense an overly high car and signal that air be exhausted.

Once you have isolated the problem, you can decide what to do. As was stated, replacement (non OEM) shocks are readily available and not too expensive. An air line adapter kit allows you to convert the factory fittings to the fittings for the new shocks. I suspect that rebuild compressors are available. The sticky point my be the electronic ride height controller. It's mounted on the frame and it's arm connects to the rear suspension via a little rod with bellcranks. The electronics inside have no moving parts but use LEDs to sense relative movement. In theory, it should last a very long time.

Please keep us posted.

Paul

FYI: Except for two replacement sets of rear shocks, the electronic level control system in my '84 Toronado has functioned without trouble for almost 25 years. It's nice to have when you 'load' passengers in the rear seat and/or have a full trunk. The system even 'trims' the ride height after I fill the fuel tank...!

[TxBuicks]

Thanks for the responses. I re-read my post and it might be a bit confusing. The compressor is mounted on a frame crossmember in front of the rear axle with air lines connected to the shocks. The compressor comes on and goes off. I can hear it come on if I sit on the tail gate. But nothing happens. It must have a timer to cut it off otherwise it will be on all the time. So I think the problem is in the shocks or the air lines. I think I'll try to tackle the original set up. The shop manual has a pretty good diagnostic chart. It is times like this that I wish I had a lift in my garage.....

[NTX5467]

Some of the factory "production" air shocks had different connectors than any of the replacement brand air shocks did, so this might be a consideration. Those earlier shocks had a rubber boot with a slide-thru spring clip to keep it in place on the shock housing . . . rather than the screw-on type fitting of the replacement brands.

IF you can interface the replacement shock's fitting with what's on the car, you can retain the self-levelling system. In some cases, as for model year 2000, the factory production shocks supercede to a pair of air shocks and all of the fittings to (apparently) deactivate the self-levelling system and make it a full-manual system. Still, if you can interface the lines and fittings to those on the vehicle, the factory self-levelling feature can be retained.

In some cases, it can be a compressor failure, too.

Regards,
NTX5467

[DShip]

As Paul mentioned, air line adapter kits are readily available and will be needed due to the fittings being different than OEM (if your current shocks are the originals). I had to use the kit on my 85 Riv when I replaced the rear shocks. I didn't have to use a kit on my 92 Riv a couple of years ago because I was able to find probably the last OEM pair of rear air shocks left/available anywhere in the world at the time. The system is great to have so in my opinion you should try to keep it working. FYI...the compressor on my 85 Riv is located under the hood on the driver's side wheel well. But, on my 92 RIV its located under carriage near the rear axle. The "under hood" advantage is that its away from the elements but the air line has to travel the full length of the car...just the opposite situation for the "under carriage" type.

[TxBuicks]

I guess mine are original because they have the spring clip to hold the lines in place. I won't be able to get serious with it for a few more weeks due to weekend trips already scheduled. Thanks for the advice and I'll keep you posted.

[Franklin31]

See www.Strutmasters.com; they are the only ones making conversion kits. and they have a lifetime warrenty.

[51dyno]

Sent you info Via email.

[DShip]

I belive in 86 the compressors went from previously being located under the hood to being attached to the rear frame crossmember. I had an 85 Riv that had the self-leveling system. I replaced the rear air shocks but had to buy a kit to change over the air line fittings as mentioned above. Most auto places sell the kit and they're very cheap $$. I also have a 92 Riv with the self-leveling system and was actually able to find at the time replacement rear air shocks with the original fitting setup, but I think those were the last ones available in the US!! This was at least 3 years back.