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Author Topic: 1977 Seville automatic load leveling compressor  (Read 5319 times)

Offline Greg McDonnell

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1977 Seville automatic load leveling compressor
« on: April 21, 2008, 08:21:08 AM »
I'm not sure if this is the appropriate forum for this question but if not, I guess it will get moved elsewhere...

While detailing my '77 Seville's engine compartment, I removed the load leveling compressor/pump or whatever it is correctly referred to.  I heard some 'rattling' in the tank so I removed it to see what was loose and if I could put the parts back where they belonged.  Four small pieces including a spring, a thimble-like plastic piece that is open on both ends, an oddly shaped metal cap and a rubber piece that looks like it fits into the spring were what I found.  Does anyone in the club repair these pumps?  I'd like to get mine working again if possible.  If not, is a wrecking yard my best source for another one?  Are these pumps problematic?  By that I mean will one from a salvage yard give me trouble down the road?  I know a new one is probably not available...

Thanks in advance for any help or advice!

Greg McDonnell
CLC#20841
« Last Edit: April 21, 2008, 08:28:28 AM by Greg McDonnell »
Greg McDonnell
CLC #20841

Offline Glen

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  • Name: Glen Houlton
Re: 1977 Seville automatic load leveling compressor
« Reply #1 on: April 22, 2008, 04:39:35 AM »
Is this the vacuum powered compressor or the electrically powered compressor?

I know nothing about the electric one.

It would help if you could post some pictures of the parts you found. 

Glen
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Offline Greg McDonnell

  • Posts: 207
Re: 1977 Seville automatic load leveling compressor
« Reply #2 on: April 22, 2008, 08:27:06 AM »
Glen,

Thanks for your offer to help! My compressor is the vacuum type.  Please see attached photo of the parts that were loose in the tank.  I had to reduce it, so you probably will have to click on the attached photo to enlarge it.

Greg McDonnell
CLC#20841
Greg McDonnell
CLC #20841

Offline Glen

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  • Name: Glen Houlton
Re: 1977 Seville automatic load leveling compressor
« Reply #3 on: April 23, 2008, 03:20:27 AM »
The spring, metal piece and rubber piece is the final check valve of the compressor.  The cylinder may be a sleeve the check valve was in. 

The rubber is the actual valve and is pressed into the outlet by the spring.  The spring is held in place by the three bladed metal piece. 

Give me a day or so to provide a picture.

Glen

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Offline Greg McDonnell

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Re: 1977 Seville automatic load leveling compressor
« Reply #4 on: April 23, 2008, 08:41:18 AM »
Glen,

THANKS very much for your explanation of the parts in the photo I provided!  I look forward to your picture.  I surely do hope I can put things back together and get the compressor working properly again.  By the way, did you notice the plastic sleeve looks like it has some 'rot' on one end.  Will that matter?

Greg
Greg McDonnell
CLC #20841

Offline Glen

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  • Name: Glen Houlton
Re: 1977 Seville automatic load leveling compressor
« Reply #5 on: April 26, 2008, 03:08:35 AM »
The output port of the compressor has a small hole in the bottom of a larger bore.  That small hole has a lip around it.  The red rubber goes against this hole.  The spring keeps it in place and the metal piece holds the spring in the bore.  The metal piece is or should be slightly domed so that when in place a tap in the center will cause it to expand slightly and hold it in the outer end of the bore. 

The sleeve is there to reduce the size of the bore so the spring and rubber stay in place. 

This arrangement forms the output or final check valve.  If this valve leaks the reservoir will leak down through the compressor. 

If this is not clear enough just ask questions.  If need be I’ll take the reservoir off one of my spares to get pictures. 

Glen 

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Offline Greg McDonnell

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Re: 1977 Seville automatic load leveling compressor
« Reply #6 on: April 27, 2008, 06:59:42 PM »
Glen,

Your explanation has been a BIG help!  Thanks very much for taking the time to post this as it explains a lot to me about how the compressor works.  I hope I can help you out some time and return the favor.  The sleeve is worn (crumbling end) so I am going to have to send it off to be professionally rebuilt.  I'd hoped I could repair it myself but I've been told, given it's age, the diaphragm needs to be replaced.  So, it's on it's way to Frank Smith in PA for a rebuild.  Hopefully it will work properly for many years to come!

Best regards, 

Greg
 
« Last Edit: April 27, 2008, 09:39:25 PM by Greg McDonnell »
Greg McDonnell
CLC #20841

Offline Glen

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Re: 1977 Seville automatic load leveling compressor
« Reply #7 on: April 28, 2008, 02:10:16 PM »
I did not know anybody was rebuilding these compressors. 

I have about a dozen around here (someday I’ll have to get them together to see how many I really have).  Only two of them have hard diaphragms. The others are all still soft and work well.  The main problems I have found on these compressors is the distributor valve gets stuck or worn.  I found one on a ’68 Fleetwood in the junkyard that I don’t think ran for very long.  The pivot screw for the distributor valve backed out and the compressor did not run for most of the life of the car.  It was as good as new inside. 

The second most common problem is leaks.  The compressor can not put out a large volume of air so a small leak takes its toll. 

Glen
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CLCMRC benefactor #104

Bob Kazawic

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Re: 1977 Seville automatic load leveling compressor
« Reply #8 on: September 06, 2008, 04:24:13 PM »
Glen, Found your post while looking for info on air suspension system for a 76 Eldorado conv. My problem is lack of knowledge on how this system works as I have no documentation or schmatics. My car is riding low in the rear and notsure if just putting air in at the port under trhe hood is the way to go as im not sure as to the correct pressure. any help in diagnosing the problem or having some documentation on this system? Owners manual says to go to the "dealer"
Bob

Online TJ Hopland

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Re: 1977 Seville automatic load leveling compressor
« Reply #9 on: September 06, 2008, 05:01:44 PM »
I think the systems are rated to something like 250 psi.  All of my cars have tended to run around 100.  Typical air compressors run to around 120 so you should be fine.    Running without air tend to wear and damage the shocks so if they have been running long with no air they may no longer hold air at all and will need to be replaced.

Is the 76 compressor electric or vacuum?
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

Offline Guidematic

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  • Name: M. Jones
Re: 1977 Seville automatic load leveling compressor
« Reply #10 on: September 07, 2008, 12:12:25 AM »
 Vacuum compressors were used from 1965-1977. They were standard on all Fleetwood models, which would include Eldorados, Sevilles and Seventy Fives. They were optional on all other cars.

 All of the compressors were the same, but they used differant tank lengths. Usually the '70's Eldorados used the short tank model.

 In addition to Cadillac models, ALC was used on other GM products. It was optional on many full sized GM models, and was standard on the 1970-1972 Monte Carlo SS454.

 Starting in 1978, they changed to what was called Electronic level Control (ELC) whioch used an electric motor to compress air on demand. The level sensor was electronic and used sealed optic sensors to sense ride height. The system was used up until just recently on many GM models.

 Mike
1970 Fleetwood Brougham 68169
1985 Eldorado Coupe 6EL57
1988 Eldorado Biarritz 6EL57
1990 Brougham d'Elegance 6DW69
1994 Fleetwood Brougham 6DW69

Offline Glen

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  • Name: Glen Houlton
Re: 1977 Seville automatic load leveling compressor
« Reply #11 on: September 07, 2008, 03:52:46 AM »
Bob, the first step is to find out what you have.  It seems very few mechanics knew anything about these systems and they modified them instead of fixing them.  The most common modification was to reroute the hoses to the shocks and put a fill valve someplace in the rear.  Frequently they were put near the gas filler. 

You should have a vacuum powered compressor under the hood.  I think in ’76 they were placed in the fender behind one of the wheel wells (left? right?).  The compressor pumps up to about 280 PSI in the reservoir.  It has attached a regulator that drops the pressure to 125 PSI and sends that out the small black tube to the rear of the car.  The compressor has a fill valve on it and can be filled from the air line at the service station.  The service station normally supplies about 100 PSI and won’t exceed the working pressure of the reservoir. 

Then you should have a leveling valve attached to the body of the car near the rear axle with a lever connected to the axle.  That senses the body height above the rear axle.  It should have two small black tubes and a larger black hose that dead ends in space.  One small tube is the supply from the compressor/regulator and the other goes to the shocks.  On some cars the tube goes to one shock and there is another tube that goes to the other shock.  Otherwise the tube has a tee and goes to both shocks. 

The shocks were frequently called Superlift shocks and were a popular addition on some cars, but those were usually manually filled.   

If you need pictures I can send pictures of the compressor and leveling valve. 

Once we know what you have then we can start the troubleshooting. 

Glen
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Offline Guidematic

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  • Name: M. Jones
Re: 1977 Seville automatic load leveling compressor
« Reply #12 on: September 07, 2008, 10:26:33 AM »

 I looked again at the pictures, and re read the original post. These parts are the expansion plug, retainer and spring from the secondary housing. This is where the compressed air enters the tank afyer it has been compressed.

 The compressor is a 2-stage compressor similar in principle to a 2-stage shop compressor. The first stage compresses the air to a nominal value where it is sent to another cylinder where it is further compressed to final pressure. The piston that faces the tank is the final stage of compression.

 You may be able to put it back together and see if it functions. You can bench test them just by hooking a vacuum line from the engine to the compressor. See video.

http://www.youtube.com/watch?v=Zs2gTHMjj6o

 Mike
1970 Fleetwood Brougham 68169
1985 Eldorado Coupe 6EL57
1988 Eldorado Biarritz 6EL57
1990 Brougham d'Elegance 6DW69
1994 Fleetwood Brougham 6DW69

Offline mechanic80

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  • Name: Norbert Bartosiak
Re: 1977 Seville automatic load leveling compressor
« Reply #13 on: January 08, 2013, 11:16:01 AM »
Well I learned something there.  Its a vacuum operated air compressor!  No wonder I couldn't find wires!  I just got my 77 Seville from Washington state yesterday.  There'll be loads of work to do to get it back to reasonable condition.
mechanic80

Offline Gene Beaird

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  • Name: Gene Beaird
Re: 1977 Seville automatic load leveling compressor
« Reply #14 on: January 10, 2013, 10:25:59 AM »
Funny!  Our 79 Seville came from Washington state, and I think the 76 the guy here in the Houston area replaced our 79 with was also from Washington state.  Too weird. 

Gene Beaird,
1968 Calais
1979 Seville
Pearland, Texas
CLC Member No. 29873

 

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