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Rebuilding ALC compressor for 72 Eldorado

Started by Loveofclassics78, February 13, 2019, 07:29:57 AM

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Loveofclassics78

Hey, is anyone out there providing any repair or rebuilding of the compressor?  Pickings are slim finding a working one.

Thanks,
Don

James Landi

Don,

When I owned a 67 Eldo back in the 1970's, I was relatively successful at rebuilding these pumps; and although the design is not complex, there are several components on the high pressure side of the pump that can, over time, simply deteriorate and be impossible to repair.  If you've studied the design, or taken one apart, you already know that corrosive moisture  when compressed, attacks the rubber valve seats and plays havoc with vital metal surfaces.  So here is my recommendation.   You absolutely need those inflatable shocks to inflate--- your car's ride will be greatly compromised as the rear end springs were designed to be aided by the inflated shocks.  The simple "work around" involves running new flexible  plumbing to each shock-- tee in a supply line to an accessible place under your rear bumper, and install a bracket that can support a schrader valve.  Then you can inflate and support your car's rear end at a height and PRESSURE that will get the rear axle at the approximate height it would be if the pump where operating.  Save the repair of the pump and its associated automatic height control for long dark winter evenings when your car is stored away, and your expectations for success are tempered by the winter weather.  Hope this helps,   James.

Mike Josephic CLC #3877

The other issue is that GM no longer offers parts
kits that assisted enabled the rebuilding of these
pumps.  So, even if you do take the pump apart,
those seals, gaskets and other deteriorated parts
ae no longer available and haven't been for about
20 years.

James is absolutely correct, those cars needed the
rear shocks to inflate to properly adjust the ride
height and handling.  Which brings up another issue.

What shape are your rear shocks in?  If they are
leaking, they are also no longer available.  They can
be replaced with a standard air shock -- and that
brings you back to James' suggestion about running
another line with a "T" fitting and schrader valve. 

That's about the only viable solution.

Mike



1955 Cadillac Eldorado
1973 Cadillac Eldorado
1995 Cadillac Seville
2004 Escalade
1997 GMC Suburban 4X4, 454 engine, 3/4 ton
custom built by Santa Fe in Evansville, IN
2011 Buick Lucerne CX
-------------------------------------
CLCMRC Museum Benefactor #38
Past: VP International Affiliates, Museum Board Director, President / Director Pittsburgh Region

chrisntam

Nothing to add other than a comment.

I'm surprised that no one makes replacement parts for these compressors, given the number of Cadillacs that had them....

>:(
1970 Deville Convertible 
Dallas, Texas

Glen

What is the condition of your compressor? Is it currently working?  Like mentioned above there is no source for parts for these compressors.  Many of the “seals” are common O rings. The worst case is if the diaphragm is ripped.  It seems the diaphragms were made of two different materials. One type gets hard and brittle the other seems to stay pliable.  New ones are not available. 
One problem is the pressure regulator mounted on the compressor.  It’s the part with the yellow cap.  If you don’t have the yellow cap then you need to look to see if the guts of the regulator is still there.  I don’t know if it was designed to be a safety valve but it does work that way.  Pressure in the reservoir is normally about 280 psi.  But pressure in the shocks can not exceed 125 psi. 
If dirt gets into the regulator valve it the pressure gets to high and the guts of the regulator gets blown out.  The dirt comes from the corrosion inside and when you fill the compressor with air using the fill valve.  It stirs up the corrosion. 
Glen Houlton CLC #727 
CLCMRC benefactor #104

cadillacmike68

Has anyone ever fitter a later design electric pump to an earlier design vacuum pump? I myself have a t-line fitting to the frame cross member behind the ear bumper, but the shocks leak out after a day or so. I carry a small inflator in the trunk for this and for tire pressure maintenance.
Regards,
"Cadillac" Mike

MaR

Quote from: cadillacmike68 on February 14, 2019, 05:38:27 AM
Has anyone ever fitter a later design electric pump to an earlier design vacuum pump? I myself have a t-line fitting to the frame cross member behind the ear bumper, but the shocks leak out after a day or so. I carry a small inflator in the trunk for this and for tire pressure maintenance.
If you wanted it to still be automatic, you most likely would have to find some other way to cycle the pump.

TJ Hopland

The control valve is in the rear on these systems so the compressor is just acting like a shop compressor,  its just trying to maintain a supply of high pressure air.   It doesn't know or care what the shocks are doing so in theory you could get an electric compressor and hook it to a small tank with a pressure switch so it would just maintain tank pressure. 

The 78? system with the electric compressor was a little different.  There wasn't a tank and there was an electronic level sensor control system.   If the sensor decided the car was low it would operate a relay that would start the compressor.  If it was sensing high it operated a valve on the compressor that vented the pressure in the system. 
StPaul/Mpls, MN USA

73 Eldo convert w/FiTech EFI
80 Eldo Diesel
90 CDV
And other assorted stuff I keep buying for some reason

Scot Minesinger

I worked on a 1972 Eldorado and am going to respectfully disagree with James and the schrader valve manul inflate idea.  I do not like the install new air shocks and inflate them at all, because if you have rear seat passengers and a full tank of gas with luggage in the trunk - inflate, then half tank of gas, just you, and no luggage, let some air out - not automatic like a Cadillac at all.  Plus too much pressure and the shocks blow.

There are two ways I would go if owned a 1971-1977 Eldorado:

1.  Install a good set of adjustable shocks in the rear that do not require air, and these are sold on Rock Auto.  I did this and the ride was fine, no issues.  Did not have a problem with height either.  Plus if you do have a slight too high or too low issue in back, the front torsion bars can adjust ride height within specifications published by the factory.

2.  Install an electric air pump from a 1978 Eldorado that feeds the air shocks.  Then you have the best of all worlds - functioning ALC and a reliable compressor.  Since the chassis is about the same from 71 thru 78, this should work ( I have not done it).  78 electric compressors from Eldorados are in slight demand for this reason.  Just like 72 Eldorado trunks to install on 71 Eldorados to get rid of the louvers.

Many will disagree and I'm braced for the barrage, but these worked for me in personal experience, and the manual fill schraeder valve definitely did not.
Fairfax Station, VA  22039 (Washington DC Sub)
1970 Cadillac DeVille Convertible
1970 Cadillac Sedan DeVille
1970 four door Convertible w/Cadillac Warranty

TJ Hopland

You have a part number or model for these adjustable shocks?   I'm having trouble grasping how a mechanically adjustable shock vs and adjustable by air shock would perform much different other than the means you have to adjust it?   Seems to me that unless you have some sort of active adjustment that they would all be pretty similar assuming you didn't have leaks in your air system.

Back when they were still easy to find in junkyards I started collecting the 80's compressors with plans to install one in my 73 but over the last 20 years it just hasn't been a big enough issue for me to kick that project up the priority list.  I can usually find a setting that works reasonably well and just leave it there.  The bigger issue I have had lately is that I have a theory that they no longer make new air shocks, what we are buying is old stock so they just don't last.   They either develop air leaks or the shock part leaks and looses its damping.   So if these mechanical ones are current production there may be an advantage there.
StPaul/Mpls, MN USA

73 Eldo convert w/FiTech EFI
80 Eldo Diesel
90 CDV
And other assorted stuff I keep buying for some reason

James Landi

I did not add too much detail to the "work around" I suggested; however, this discussion does yield a great deal of insight, experience, and wisdom.  On my 80's ELdos, (I owned three), I installed an electric pump OVER RIDE under the dash, and detached the electric pressure purge part of the pump.  I also "tee in" an inexpensive oil pressure gauge that I hung under the dash, so I could  add air at the start of a trip, and monitor the pressure in the shocks.  Here's what I learned... in the newer 80"s generation of air level control and "down sized" Eldo, around 80 pounds of pressure gave me a nice lift, allowed me to see out of the rear window and provided a stiffer rear feel to the car.  There was always a slow "bleed down" as the newer design has an emergency pressure purge valve build into the main feed from the pump.  It's a brass or bronze device, and I suspect it's designed to let out pressure that could rupture the air shock, that  major or minor bumps cause it to bleed pressure on occasion.   On my 72 Eldo, that I rigged up the schrader valve under the bumper, I installed one of those emergency bleeders, and I would not pump in more than 60-80 pounds. As I did not use it for long trips, or have a lot of weight in it, I would inflate the shocks to a rear height that I liked, and drive away.  After several days of not driving, I would re-inflate to between 60-80 pounds, and get the rear end to a height that I liked.  Now as noted above, too much unregulated pressure and too much weight in the car can blow out the system.  I had a stock air system in my 83 when I initially purchased the car, and it  did just that when I was towing my 14 '  outboard and had two heavy folks in the rear seat-- hit a bump, and pow!-- sounded like a gun went off-- I purchased a used electric pump to fix that problem.  All this is to say, that with the "newer" electric pump, an emergeny purge device, a momentary on high amperage button and an inexpensive oil pressure gauge, you can control the height, and monitor the pressure as you drive.     James

cadillacmike68

James,

That sounds like a lot of work and parts. I wouldn't mind being able to add air from inside the car, but like you said, I air them up before a drive to a height I like, 60-80psi like you, and then I'm fine for the day. But they seem to bleed down quite fast; only 1-2 days and the pressure is gone. That's OK because I have a heavier duty pump in the garage and a light duty inflator in the trunk.

It's just another PMCS check, Laurie will know this is...
Regards,
"Cadillac" Mike

Scot Minesinger

This inflating your air shocks manually every day or every time it is driven seems to me a huge pain, and I would not do it.  Driving these cars should be a pleasure.  In my 1970 Cadillac everything is preset, radio station to the one I want, climate control to setting I want, twilight sentinal to turn on headlights as it gets dark, and etc.  I just get in the car, start it, put the top down (no boot), and drive off.  For your 1972 Eldoardo I would install non-air shocks, an electric air compressor from a 1978 Eldorado, or have the original fixed somehow (the reason you started the post). 
Fairfax Station, VA  22039 (Washington DC Sub)
1970 Cadillac DeVille Convertible
1970 Cadillac Sedan DeVille
1970 four door Convertible w/Cadillac Warranty

TJ Hopland

If you have to add air every few days you have a signifigant leak. 

If I have to add air more than every 6 months I go looking for a leak and hope to find one I can fix because I'm way to busy and lazy to be messing with air every time I want to drive.
StPaul/Mpls, MN USA

73 Eldo convert w/FiTech EFI
80 Eldo Diesel
90 CDV
And other assorted stuff I keep buying for some reason

Scot Minesinger

TJ Hopland,

I could certainly live with every six months adding air.  Heck every 18 months I have to replace my convertible top switch (the reproductions last about a season and a half).  Anyway we generally drive these cars alone or with one passenger (maybe 2), empty trunk, and full to half tank of gas, so level control variation would be minimal.
Fairfax Station, VA  22039 (Washington DC Sub)
1970 Cadillac DeVille Convertible
1970 Cadillac Sedan DeVille
1970 four door Convertible w/Cadillac Warranty

bcroe

Quote from: James Landiin the newer 80"s generation of air level control and "down sized" Eldo, around 80 pounds of pressure gave me a nice lift, allowed me to see out of the rear window and provided a stiffer rear feel to the car.  James

Seeing out the rear is an important part of defensive driving, and
I saw the problem on my 79 Toro decades ago.  What I did was add
some spacers to the level detect control in the back so it would set
the rear higher.  AND I remounted the rear view mirror inches lower
than normal, this did the trick. 

The 79 does not have the generous trunk like my other cars, I do not
expect the weight to vary greatly.  Passengers can vary, but this weight
is so much farther forward as to have less effect.  The long term plan
(parts already here) is swap good KYB gas shocks (like the front) in
place of the poor performance air shocks, and adjust the springs or
mounts to get my height.  Performance handling and reliability trump
ALC.  Bruce Roe

James Landi

Cadillac Mike mentioned that he simply adds air at his non functioning pressure pump, and that works as a temporary fix for the day.  A reasonable way to handle the challenge, but the leak down is inevitable because the height adjuster at the axle  is still doing its assigned work, and constantly modulating the height.  Unfortunately, without any additional volume of pressurized air, you lose most of it as you drive.  A work around here would have you install an electric air pump, and a set up that would limit the pressure of the pump... this could be done with some sort of air pressure switch, so you would not overtax the entire system with your electric pump running constantly.  ALl this is to say, that there are creative work arounds that can get the height, rear site lines, and improved road manners fixed.    James

Highwayman68

Is Derek Sherwood still around (CLC# 18781).

Here is something that he posted back in 2002 in the CadillacParts Yahoo group that I kept. It seems today there are enough people interested in this that we might be able to get a kit produced.

******************
Hello,

I'm a Cadillac enthusiast and CLC member working on producing a
rebuild kit for the level control air compressors used in Cadillacs
from 1965-1977.  Thus far, no such kit has been available, and parts
have long since become obsolete.

The kit should contain the following parts:

2 Regulator Assembly o-rings
1 service valve core
1 regulator to compressor o-ring
1 upper piston assembly o-ring
1 lower piston assembly o-ring
1 diaphragm retainer/snap ring
1 diaphragm
1 cover o-ring
1 cover cork gasket
1 valve tension spring
2 nylon washers
1 arm tension spring
1 intake valve retaining spring
1 compressor to reservoir o-ring
2 check valves
2 check valve springs

Ideally, the kit price will be $39.99, available through my website:

http://www.geocities.com/levelrideparts

I need at least 200 kit orders to be financially viable and make this
a go.  No money is changing hands at this time, but expressions of
interest are appreciated.  Hopefully, the kits will be available
sometime in the next few months.  While this is not a full rebuild
kit, it is the most complete kit of wear items that I have been able
to put together at a reasonable price.

Please come visit my site!

Thanks,

Derek J. Sherwood, CLC #18781
dsherwoo@ycp.edu
**********************
1968 Fleetwood Purchased in 1981

bcroe

A work around might be get one of those tire inflators offered for $10.
Leave the original system in place, but bring the OEM motor wires
over to the new unit, and tie its air output into the pressure line. 

Bruce Roe

cadillacmike68

Quote from: James Landi on February 17, 2019, 08:32:58 AM
Cadillac Mike mentioned that he simply adds air at his non functioning pressure pump, and that works as a temporary fix for the day.  A reasonable way to handle the challenge, but the leak down is inevitable because the height adjuster at the axle  is still doing its assigned work, and constantly modulating the height.  Unfortunately, without any additional volume of pressurized air, you lose most of it as you drive.  A work around here would have you install an electric air pump, and a set up that would limit the pressure of the pump... this could be done with some sort of air pressure switch, so you would not overtax the entire system with your electric pump running constantly.  ALl this is to say, that there are creative work arounds that can get the height, rear site lines, and improved road manners fixed.    James

I don't have a non-functioning pump. My 68 never had ALC, but I wanted to be able to adjust the rear height to accommodate varying loads so I had air shocks with the feed lines going to the rear bumper. Problem is that they leak down too fast. I've had them leak checked and have had the shocks replaced but they still leak down too fast. Time for another thorough leak test i guess.

And if you don't give your car a once around every time you take it out, you are wrong.  In the Army it was called PMCS but the troops shortened it to PMS. Navy, what did you call it?
Regards,
"Cadillac" Mike