Home » Public Forums » GMCnet » Replacing air compressors
| Replacing air compressors [message #364737] |
Tue, 15 June 2021 21:09  |
kwharland
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Location: Central Florida
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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
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| Re: Replacing air compressors [message #364740 is a reply to message #364738] |
Tue, 15 June 2021 22:35  |
kwharland
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Tom Lins wrote on Tue, 15 June 2021 23:21To 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
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| [GMCnet] Re: Replacing air compressors [message #364744 is a reply to message #364739] |
Wed, 16 June 2021 08:45 |
Keith V
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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
________________________________
From: Tom Lins
Sent: Tuesday, June 15, 2021 10:23 PM
To: gmclist@list.gmcnet.org
Subject: [GMCnet] Re: Replacing air compressors
Watch this it might help
https://www.youtube.com/watch?v=bxkA9sNjTiA
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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/
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ask me about MicroLevel
Cell, 763-732-3419
My427v8@hotmail.com
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| Re: [GMCnet] Re: Replacing air compressors [message #364745 is a reply to message #364744] |
Wed, 16 June 2021 09:51 |
kwharland
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Location: Central Florida
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Keith V wrote on Wed, 16 June 2021 09:45Whie 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] Re: Replacing air compressors [message #364746 is a reply to message #364745] |
Wed, 16 June 2021 10:53 |
Keith V
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Location: Mounds View,MN
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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@list.gmcnet.org
Subject: [GMCnet] Re: Replacing air compressors
Keith V wrote on Wed, 16 June 2021 09:45
> 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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Keith Vasilakes
Mounds View. MN
75 ex Royale GMC
ask me about MicroLevel
Cell, 763-732-3419
My427v8@hotmail.com
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| Re: [GMCnet] Re: Replacing air compressors [message #364747 is a reply to message #364746] |
Wed, 16 June 2021 11:36 |
kwharland
Messages: 246
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Location: Central Florida
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Keith V wrote on Wed, 16 June 2021 11:53I 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 the necessary items making it road worthy and let him worry about that function.
1978 Eleganza II
[Updated on: Thu, 17 June 2021 06:53] Report message to a moderator |
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| [GMCnet] Re: Replacing air compressors [message #364750 is a reply to message #364747] |
Wed, 16 June 2021 12:23 |
James Hupy
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EL II compressors have a dessicant/dryer inlet air filter. The exhaust port
is in the head,
Jim Hupy
Salem, Oregon
On Wed, Jun 16, 2021, 9:41 AM Ken Harland wrote:
> Keith V wrote on Wed, 16 June 2021 11:53
>> 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
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| [GMCnet] Re: Replacing air compressors [message #364756 is a reply to message #364755] |
Wed, 16 June 2021 15:27 |
James Hupy
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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 wrote:
> James Hupy wrote on Wed, 16 June 2021 13:23
>> 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
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| [GMCnet] Re: Replacing air compressors [message #364757 is a reply to message #364756] |
Wed, 16 June 2021 16:12 |
jimk
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Location: Belmont, CA
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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
On Wed, Jun 16, 2021 at 1:27 PM James Hupy wrote:
> 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
> wrote:
>
>> James Hupy wrote on Wed, 16 June 2021 13:23
>>> 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
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Applied/GMC, Newark,CA
jimk@appliedairfilters.com
http://www.gmcrvparts.com
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| Re: [GMCnet] Re: Replacing air compressors [message #364770 is a reply to message #364756] |
Thu, 17 June 2021 06:26 |
kwharland
Messages: 246
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Location: Central Florida
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James Hupy wrote on Wed, 16 June 2021 16:27Ken, 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. The filter you mentioned is on the compressor output, not inlet.
1978 Eleganza II
[Updated on: Thu, 17 June 2021 06:54] Report message to a moderator |
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| Re: [GMCnet] Re: Replacing air compressors [message #364771 is a reply to message #364757] |
Thu, 17 June 2021 06:28 |
kwharland
Messages: 246
Registered: November 2005
Location: Central Florida
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jimk wrote on Wed, 16 June 2021 17:12Ken,
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 understand about the bleed off system and how others have accomplished that with newer compressors.
1978 Eleganza II
[Updated on: Thu, 17 June 2021 06:50] Report message to a moderator |
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| Re: [GMCnet] Re: Replacing air compressors [message #364772 is a reply to message #364771] |
Thu, 17 June 2021 07:06 |
Russell K.
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Location: Dunedin, Florida
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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
1978 Eleganza II, Dunedin, Florida
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| Re: [GMCnet] Re: Replacing air compressors [message #364816 is a reply to message #364772] |
Fri, 18 June 2021 08:39 |
kwharland
Messages: 246
Registered: November 2005
Location: Central Florida
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Russell K. wrote on Thu, 17 June 2021 08:06Hi 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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