Rebuilding air compressor on M923A2 rebuild kit information

[klugpi]

I have an air compressor problems for sometime, finally took the head off the compressor last night it's all ______ up,here some rebuild kit information for my compressor my compressor is a HOLSET number 3558006 - SS296. Cummins west does not carry any rebuild kits for this compressor don't waste your time with Cummins. Haldex has a few kits a major rebuild kit Haldex number 355954sK, but no one stocks it. Haldex also has another major rebuild kit 3559509K they want two weeks lead time. Haldex also has this minor rebuild kit part number 3559511K FinditParts.com has it for $32, however find a parts.com has a Meritor Air compressor unload kit #R9553559545N for $29 and it has more gaskets in it, it has the gaskets the connect compressor to the block and to the Power steering pump as well. the Haldex minor kit did not have those other two gaskets so it's worth it for less money to get the Meritor R955359545N kit. Good luck out there, respectfully Bill Klug out

 

[dmetalmiki]

Thank you for posting that useful information in such clarity. It will bound to be a useful reference for someone somewhere sometime.

 

[klugpi]

The problems I have experience on the air system on my am 923 A2 1991 are the air dryer the regulator the PPV ( pressure protection valve be the pressure protection valve) which is located primary tank that doesn't allow air out of primary tank to the auxiliary tanks unless it has so many psi (30lb) (I think) those are the three key places the regulator the PPV and then the air compressor haed. If you take the pressure air line off the compressor and you can hold your thumb over the leak & it's not blowing hard enough to blow your thump away your head is most likely the issue it's a $45 shipping & handling included kit. Most likely you have a broken spring and maybe the internal gasket is bad but change all the gaskets and seals on it you probably don't need the major overhaul kit and less I some hard parts are damaged inside because the the minor kit comes with a spring and all the gaskets and seals most likely the spring is broken. If you have Strong air coming out of the compressor and your horn doesn't work in your windshield wipers don't work because the air isn't leaving the primary tank and going into your auxiliary tanks. You will first lose use of airhorn and then you'll lose your windshield wipers that's probably the PPV pressure protection valve located on the primary tank it doesn't let the air out of the primary tank to the auxiliary tanks. These four things can especially the PPV & air regulator can cause problem with Central tire inflation system. It can act like you have problems with all kinds of things. if you can't find any leaks check regulator, dryer ,PPV and then the compressor head; those four things are most likely the cause and or the root to all your problems and maybe a combination of all four or three things can cause your especially the PPV, dryer & the regulator. The regulator that they sell at Napa you have to grind part of the housing a way to make it fit with the big brass plumbing connection fitting. Good luck respectfully Bill Klug out

 

[klugpi]

The problems I have experience on the air system on my am 923 A2 1991 are the air dryer the regulator the PPV ( pressure protection valve be the pressure protection valve) which is located primary tank that doesn't allow air out of primary tank to the auxiliary tanks unless it has so many psi (30lb) (I think) those are the three key places the regulator the PPV and then the air compressor haed. If you take the pressure air line off the compressor and you can hold your thumb over the leak & it's not blowing hard enough to blow your thump away your head is most likely the issue it's a $45 shipping & handling included kit. Most likely you have a broken spring and maybe the internal gasket is bad but change all the gaskets and seals on it you probably don't need the major overhaul kit and less I some hard parts are damaged inside because the the minor kit comes with a spring and all the gaskets and seals most likely the spring is broken. If you have Strong air coming out of the compressor and your horn doesn't work in your windshield wipers don't work because the air isn't leaving the primary tank and going into your auxiliary tanks. You will first lose use of airhorn and then you'll lose your windshield wipers that's probably the PPV pressure protection valve located on the primary tank it doesn't let the air out of the primary tank to the auxiliary tanks. These four things can especially the PPV & air regulator can cause problem with Central tire inflation system. It can act like you have problems with all kinds of things. if you can't find any leaks check regulator, dryer ,PPV and then the compressor head; those four things are most likely the cause and or the root to all your problems and maybe a combination of all four or three things can cause your especially the PPV, dryer & the regulator. The regulator that they sell at Napa you have to grind part of the housing a way to make it fit with the big brass plumbing connection fitting. Good luck respectfully Bill Klug out

 

[simp5782]

The unloader kit for that compressor is 3559545K and is available thru my local truckpro and truck parts specialist. Memphis equipment also stocks em. As far as compressors go. It is around $450 and stocked in a few warehouses around the country. Houston,Chicago,Atlanta,Denver to name a few.

It is also an SS296C compressor.

 

[sweetk30]

i did a refresh of a top end on one for a 936a2 with 8.3 in it . https://www.steelsoldiers.com/showt...ssor-rebuild-info-or-service-specs&highlight=

1 i did just needed gaskets .



she is pumping air good to this day .

 

[CARMAN]

Rebuilt my air compressor today. All went well but have air seeping back into compressor. Seems to be coming back from secondary tank. So with that, the compressor keeps cycling on and then the dryer blows off like every minute or two. SIMP...you had another member on here you had explained what valve to check/replace to stop this I think??

 

[simp5782]

Your air dryer has a check valve in it to prevent back feed to the compressor. The purest air dryers I know for sure have it in them.

If your tanks are reading the correct pressure then you should not be cycling often. Did you see if it continues after you remove the line off the compressor?

 

[CARMAN]

I have not. I have a new air dryer but have not installed yet since mine seemed to work fine. The valve behind the front bumper keeps bleeding off as well.

 

[simp5782]

I have not. I have a new air dryer but have not installed yet since mine seemed to work fine. The valve behind the front bumper keeps bleeding off as well.

How do you know it is the Q2 valve? Just cause it is dumping air out of the intake stack does not necessarily mean it is a Q2 valve.. likely candidate but a blown service brake diaphragm will do the same thing.

Q2 valve simple check is to remove the white line going to it on the bottom port and press your brake pedal and see if you hear the large air woosh from the front of the truck or if it is still going thru the intake stack.

 

[CARMAN]

I don't know that it is the Q2. I was just stating that the Q2 valve is relieving are pressure more often than in the past. The air compressor pumps up fast but then the secondary tank goes down just parked and running causing the compressor to come back on. Then a minute later the Q2 bleeds off, the air dryer pops again. Then repeat. If I shut the truck off and jump up on the tire I can here air running back into the air compressor. I assume that is why the gasket was blown out inside.??

 

[CARMAN]

I don't know that it is the Q2. I was just stating that the Q2 valve is relieving are pressure more often than in the past. The air compressor pumps up fast but then the secondary tank goes down just parked and running causing the compressor to come back on. Then a minute later the Q2 bleeds off, the air dryer pops again. Then repeat. If I shut the truck off and jump up on the tire I can here air running back into the air compressor. I assume that is why the gasket was blown out inside.??View attachment 746763

 

[simp5782]

Q2 valve should not bleed off unless the brake pedal is pushed. It does not receive air until you push the pedal.

 

[CARMAN]

Not sure what is going on then. I do not have air leaking into the intake stack like people talk about. Only when i take my foot off the brake. The valve at the front of the truck behind the bumper that has a bleed of exit off the driver side like an air dryer is letting air out of it at odd times. It actually does it while the ctis is adding air to the tires when truck is first started and tanks are topped off. After tanks are full this valve seems to release air on and off. and I hear air returning to the air compressor after shutting down the truck which is causing the air compressor to cycle almost non stop. I will change the air dryer out and see if it changes things.

 

[Jbulach]

I think your talking about the quick release valve for the CTIS for the front axle. If your front tires are at hwy pressure and you have a low rear tire or two, the front will dump air out of the front tires until all the tires equalize. This process will consume a lot of air...

 

[CARMAN]

I think your talking about the quick release valve for the CTIS for the front axle. If your front tires are at hwy pressure and you have a low rear tire or two, the front will dump air out of the front tires until all the tires equalize. This process will consume a lot of air...

have not had time to replace air dryer but here is valve bleed off. Think this is what you are speaking of. Just don’t remember it ever cycling as much as it is now.

 

[CARMAN]

This should maybe go in the air dryer thread but I finally installed the new dryer after the air compressor rebuild. After the ctis finished I am still having an issue where the second tank is slowly bleeding down causing the compressor to come back on every few minutes. It only runs for a minute. Just enough to top off the tank. Been all over with soapy water and when I shut the truck off it holds air. I’m stumped. Here is air dryer picture. And what is this valve for? It is in the frame just up from the dryer.

 

[simp5782]

This should maybe go in the air dryer thread but I finally installed the new dryer after the air compressor rebuild. After the ctis finished I am still having an issue where the second tank is slowly bleeding down causing the compressor to come back on every few minutes. It only runs for a minute. Just enough to top off the tank. Been all over with soapy water and when I shut the truck off it holds air. I’m stumped. Here is air dryer picture. And what is this valve for? It is in the frame just up from the dryer.

Emergency overpressure valve. There is one on the top of the fitting on the line going into the wet tank as well.

Is your check valve good on the secondary tank? It can have a weak spring and leak air back across. Usually it tends to creek if it is doing this. Might need to put something metal on it and see if you hear it closely. Secondary tank supplies air to the #7 double check valve and into the spring tank. Option there is to get a air fitting adapter to screw that small air line on at the #7 double check valve and put a plug on it to see if leaks down. If so then The secondary tank goes to the treadle valve sharing air to the shutterstat on that top T fitting. . Options are to pull the line going to the shutterstat and put a JIC plug in it and see if you still have a leak down. If you do then you are looking at a treadle valve leaking over some. It also feeds the gauge. Simple check on that is to pull the fitting on the side firewall and put a plug in it or spray bottle and check for leaks.

put some soap and water directly in the rear service gladhand and then open it up and let it sit and see is bubbles emerge that shoes a leaking treadle valve.

 

[CARMAN]

Ok. I’m back and still can’t get this thing right. I have rebuilt the top end of the air compressor. I have replaced the air dryer but still the air compressor cycles like every minute for about 10-15 seconds. I actually shut off both valves off the main tank so only air goes to that. I hear no leakes (that I can hear while engine running) but the saga continues. I can not even really see the pressure go down on either gauge. I have sprayed soapy water on everything. But the compressor continues to cycle every minute or so and then the dryer blows off.

 

[CARMAN]

Ok. I’m back and still can’t get this thing right. I have rebuilt the top end of the air compressor. I have replaced the air dryer but still the air compressor cycles like every minute for about 10-15 seconds. I actually shut off both valves off the main tank so only air goes to that. I hear no leakes (that I can hear while engine running) but the saga continues. I can not even really see the pressure go down on either gauge. I have sprayed soapy water on everything. But the compressor continues to cycle every minute or so and then the dryer blows off.

Bumping this hoping for help from you SIMP.