Auto Level Control

[Ronnie]

Any tips on restoring and repairing the auto level control on my 74 Eldorado Convertible? I was told that there was an article many years ago in the Self Starter, but have unable to find it.  Ronnie Hux #22524

[Barry]

Is your pump under the hood working ? If so, usually the leveling valve needs cleaning and the lines from the front to back should be inspected. Just replaced the factory shocks on my 76 convertible with Gabriels, which are now hooked up to the original pump and keeping the car completely level. The biggest problem is rebuilding the pump. Apparently there are no parts for them.

[Glen]

I can never remember when Cadillac went from the vacuum operated compressor to the electric compressor. 

If you have a vacuum compressor I may be able to guide you through getting it going again.  First you have to determine if the compressor is running.  You can tell from feeling it, you should feel a thump as it runs.  The frequency of the thumps is variable depending on how much air is being used.  More air faster thumps. 

Did you ever have the ALC working on this car? 

[Ronnie]

It worked a couple of years ago. My mechanic checked all the lines, valves, shocks, and leveling valve in the rear. He put air into the tank, but that leaked out.  He said the compressor is not working.

[TJ Hopland]

I'm pretty sure 78 was the start of electric compressors.    At least those were under the hood still.   You got to wonder who thought it was a good idea to mount them under the car near the axle in the 90's

[Glen]

Finding the leak is the first thing.  How fast does it leak down? 

Before you put any more air in the compressor you need to read this web page.  http://www.planeteldorado.com/ALC/index.html

The air bags on the shocks are the first suspects, also they can leak around the top mounting stud. There is only one fix, replace the shocks.  . 

All other points can be checked fairly easily.  Using a mix dish detergent (Dawn is best) or get the kids bubble solution and paint or spray on the seams of the compressor around the regulator and all joints of the hoses.  If you see bubbles there is a leak there.  The smaller the bubbles the smaller the leak.  Large leaks may just blow the soap off before it can bubble up, but you can usually feel or hear that large of a leak. 

There is one more source of a leak and that is the check valves internal to the compressor.  To check those disconnect both the vacuum hose and air intake hose at the far end and put the ends of both of them in a glass of water.  If you get bubbles out of either of the hoses the check valves leak.   To detect the smaller leaks you need to keep the hose ends as shallow in the water as you can. 

When you are ready I’ll help you get the compressor running again.