Replacing air compressors

K

ken harland

New member
Dec 30, 2005
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I'm in the process of replacing the air compressors and I'm puzzled as to how the OEM system released pressure. The original compressors have an
internal solenoid valve that's in series with the external shut off valve. And according the schematics, both are energized in the 'lower' mode which
I interpret to mean the air in the suspension goes back through the compressor. But I don't see when the OEM compressor's air inlet is. Perhaps that
large black cylindrical piece is more than a muffler and plays a role in bleeding off air pressure. I'm stumped at the moment and would appreciate
some guidance.
--
1978 Eleganza II
 
To answer that we need to know if you have Electrolevel 1 or Electrolevel 2
If you have 6 air solinoids with the compressor you have Electrolevel 1
If you have less you have Electrolevel 2
--
Tom Lins
St Augustine, FL
77 GM Rear Twin, Dry Bath, 455, Aluminum Radiator Quad-Bag Suspension Solar Panel
Manuals on DVD
YOUTUBE Channel: GMC Dealer Training Tapes
http://www.bdub.net/tomlins/
 
> To answer that we need to know if you have Electrolevel 1 or Electrolevel 2
> If you have 6 air solinoids with the compressor you have Electrolevel 1
> If you have less you have Electrolevel 2
Electro Level 2, dual compressors.

--
1978 Eleganza II
 
I recently replaced my old compressor with a Viair and it's vastly better. Well, I suppose 40 years of service takes its toll on anything. I have
Electrolevel I in my 1976 Palm Beach, so I'm no help with your rig, but I can attest that the new compressor is an investment worth making. I have a
leak somewhere in the system that has eluded my best efforts to find and the money I've tossed away having others look for it, but this compressor
pumps the bags up and I isolate the bags with the valve and I'm on my way.
--
Larry Davick
A Mystery Machine
1976(ish) Palm Beach
Fremont, Ca
Howell EFI + EBL + Electronic Dizzy
 
Whie an interesting video it does not apply to OP.
OP has an EL2, not a PL.

Ken, you are correct that two valves are involved to lower, the hold valve which is the external valve and the lower valve which is hidden in the compressor head. The air inlet/exit is indeed hard to see but is in there.

If you are replacing the compressors I would expect to have to also replace the lower solenoid which would be mounted external to the compressor. IDK why GM put the lower solenoid inside the compressor, but the hold solenoid outside, must have been cheaper somehow.

Get the biggest baddest air compresser you can find. No on has ever complained that their compressor is too big.

Also consider adding a pressure switch, EL2's, from what I know, did not use a pressure switch and if you put in a modern compressor seriously run the risk of over pressuring the system.

Keith Vasilakes
Mounds View MN
76 exRoyale
MicroLevelhttp://www.gmcmotorhomemarketplace.com/vasilakes/microlevel_intro.pdf

________________________________
From: Tom Lins
Sent: Tuesday, June 15, 2021 10:23 PM
To: gmclist
Subject: [GMCnet] Re: Replacing air compressors

Watch this it might help

https://www.youtube.com/watch?v=bxkA9sNjTiA

--
Tom Lins
St Augustine, FL
77 GM Rear Twin, Dry Bath, 455, Aluminum Radiator Quad-Bag Suspension Solar Panel
Manuals on DVD
YOUTUBE Channel: GMC Dealer Training Tapes
http://www.bdub.net/tomlins/
_______________________________________________
GMCnet mailing list
Unsubscribe or Change List Options:
 
> Whie an interesting video it does not apply to OP.
> OP has an EL2, not a PL.
>
> Ken, you are correct that two valves are involved to lower, the hold valve which is the external valve and the lower valve which is hidden in the
> compressor head. The air inlet/exit is indeed hard to see but is in there.
>
> If you are replacing the compressors I would expect to have to also replace the lower solenoid which would be mounted external to the compressor.
> IDK why GM put the lower solenoid inside the compressor, but the hold solenoid outside, must have been cheaper somehow.
>
> Get the biggest baddest air compresser you can find. No on has ever complained that their compressor is too big.
>
> Also consider adding a pressure switch, EL2's, from what I know, did not use a pressure switch and if you put in a modern compressor seriously run
> the risk of over pressuring the system.
>
> Keith Vasilakes
> Mounds View MN
> 76 exRoyale
> MicroLevel

Thanks Keith, the compressors I have are doing a good job of raising it quickly so good idea about a pressure switch. I was thinking the system
needed remote gauges adjacent to the controls to both monitor and prevent overfilling.

As for the hold valves, I'm using the original mount and the hold valves are in the same place. I'll look again for the air input, it has to be
there. As I think about the OEM configuration and it's applications, it makes sense to have the internal solenoid valve instead of check valves - it
make the system simple for the raise and lower functions.

Ken

At this point I believe to achieve the same functionality, I'd have to tee in another valve which would require a wiring change.

--
1978 Eleganza II
 
I THINK the air input is underneath the compressor head, I have a system at home I can look at tonight if you still need me to.
How did you handle the dump valves?
________________________________
From: Ken Harland
Sent: Wednesday, June 16, 2021 9:51 AM
To: gmclist
Subject: [GMCnet] Re: Replacing air compressors

> Whie an interesting video it does not apply to OP.
> OP has an EL2, not a PL.
>
> Ken, you are correct that two valves are involved to lower, the hold valve which is the external valve and the lower valve which is hidden in the
> compressor head. The air inlet/exit is indeed hard to see but is in there.
>
> If you are replacing the compressors I would expect to have to also replace the lower solenoid which would be mounted external to the compressor.
> IDK why GM put the lower solenoid inside the compressor, but the hold solenoid outside, must have been cheaper somehow.
>
> Get the biggest baddest air compresser you can find. No on has ever complained that their compressor is too big.
>
> Also consider adding a pressure switch, EL2's, from what I know, did not use a pressure switch and if you put in a modern compressor seriously run
> the risk of over pressuring the system.
>
> Keith Vasilakes
> Mounds View MN
> 76 exRoyale
> MicroLevel

Thanks Keith, the compressors I have are doing a good job of raising it quickly so good idea about a pressure switch. I was thinking the system
needed remote gauges adjacent to the controls to both monitor and prevent overfilling.

As for the hold valves, I'm using the original mount and the hold valves are in the same place. I'll look again for the air input, it has to be
there. As I think about the OEM configuration and it's applications, it makes sense to have the internal solenoid valve instead of check valves - it
make the system simple for the raise and lower functions.

Ken

At this point I believe to achieve the same functionality, I'd have to tee in another valve which would require a wiring change.

--
1978 Eleganza II
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GMCnet mailing list
Unsubscribe or Change List Options:
 
> I THINK the air input is underneath the compressor head, I have a system at home I can look at tonight if you still need me to.
> How did you handle the dump valves?

Yes, I found the inlet and remembered finding it once before...I knew it had to be somewhere. I have not tackled 'dump' valves at this point, the
soon to be new owner has indicated he'd prefer I completed items making it road worthy and let him worry about that function.

--
1978 Eleganza II
 
EL II compressors have a dessicant/dryer inlet air filter. The exhaust port
is in the head,
Jim Hupy
Salem, Oregon

> > I THINK the air input is underneath the compressor head, I have a system
> at home I can look at tonight if you still need me to.
> > How did you handle the dump valves?
>
> Yes, I found the inlet and remembered finding it once before...I knew it
> had to be somewhere. I have not tackled 'dump' valves at this point, the
> soon to be new owner has indicated he'd prefer I completed items making it
> road worthy and let him worry about that function.
>
> --
> 1978 Eleganza II
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
>
 
Ken, send me a phone number where I can text you some pictures of a GMC EL
II system. I will send you info offnet to explain. My phone number is 503
931- Fourty nine 88.
Jim Hupy
Salem, Oregon

> > EL II compressors have a dessicant/dryer inlet air filter. The exhaust
> port
> > is in the head,
> > Jim Hupy
> > Salem, Oregon
>
> I don't believe that's correct Jim, see attached picture.
>
> https://drive.google.com/file/d/1VMHBfkZGzOClD35fOtY_2vXCJ7-WFe2-/view?usp=sharing
>
> --
> 1978 Eleganza II
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
>
 
Ken,
You have a 78 system and the unit has a built in bleed on the head of the
compressors.
So it is different than the 73-77

> Ken, send me a phone number where I can text you some pictures of a GMC EL
> II system. I will send you info offnet to explain. My phone number is 503
> 931- Fourty nine 88.
> Jim Hupy
> Salem, Oregon
>
> On Wed, Jun 16, 2021, 12:05 PM Ken Harland

>

> > > EL II compressors have a dessicant/dryer inlet air filter. The exhaust
> > port
> > > is in the head,
> > > Jim Hupy
> > > Salem, Oregon
> >
> > I don't believe that's correct Jim, see attached picture.
> >
> >
> https://drive.google.com/file/d/1VMHBfkZGzOClD35fOtY_2vXCJ7-WFe2-/view?usp=sharing
> >
> > --
> > 1978 Eleganza II
> > _______________________________________________
> > GMCnet mailing list
> > Unsubscribe or Change List Options:
> >
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
>

--
Jim Kanomata ASE
Applied/GMC, Newark,CA
jimk
http://www.gmcrvparts.com
1-800-752-7502
 
> Ken, send me a phone number where I can text you some pictures of a GMC EL
> II system. I will send you info offnet to explain. My phone number is 503
> 931- Fourty nine 88.
> Jim Hupy
> Salem, Oregon

Thanks for the offer but I have a complete EL II system that I'm upgrading with new compressors. Mine is/was original with all the components but
with one bad motor.
--
1978 Eleganza II
 
> Ken,
> You have a 78 system and the unit has a built in bleed on the head of the
> compressors.
> So it is different than the 73-77
Yes, see my reply above, I know what I have and I was just seeking to confirm what I've deduced about the bleed off system.

--
1978 Eleganza II
 
Hi Ken,

I have a '78 with the EL-II system also. Are you planning to replace the electronic height sensors as well? Have you found a suitable replacement
part for them? I have not. Are you planning to put in two new compressors, or just one and a air tank? If two compressors, are you installing high
pressure cut off switches? Just curious, thanks.

Russell

--
Russell Keith,
1978 E2 "Harry" 403 (still carbureted), Danny Dunn Tranny, Thorley, Stock Brakes w/Remote Vacuum Brake Booster, Quad Bags, Dakota Digital Dash, 6.5 kW
Onan, Dunedin, Florida
 
> Hi Ken,
>
> I have a '78 with the EL-II system also. Are you planning to replace the electronic height sensors as well? Have you found a suitable replacement
> part for them? I have not. Are you planning to put in two new compressors, or just one and a air tank? If two compressors, are you installing
> high pressure cut off switches? Just curious, thanks.
>
> Russell

Yes, two compressors but as for the other details, I'm leaving those to the soon-to-be new owner. I did receive this photo of newer sensor and
controls from another long time GMC owner.

https://drive.google.com/file/d/1ub5pZuroIl8OuH6s5vUhm88Ugz5XjLCL/view?usp=sharing
--
1978 Eleganza II
 
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