M923a2 building air to frequently

[Skullmaster]

My m923a2 has had this issue sine I picked it up from auction, it builds up to 120psi, you then here the blow off of the dryer indicating the compressor has stopped pumping air, and you can hear it's not pumping, then about less than a minute later it turns back on, at this point the guage has not even dropped, runs for about a minute then shuts back off. I have swapped out the air governor with a brand new one and it does the exact same thing. Thoughts or suggestions on where to go from here?

 

[NDT]

I forgot, can the governor cut in pressure be adjusted down some? (Check TM). Also make sure there are no leaks anywhere.

 

[Bighurt]

Sounds like the governor is out of adjustment as mentioned. Additionally and quite possibly your gauge may not be accurate. Also I believe the gauge reads the secondary tank, where as the governor runs off the supplied pressure from the wet tank. If you have a pressure protection or wet tank leak the governor would continue to request air pressure even though the gauge for the secondary tank may not be dropping due to the check valve.

But I'm not an air expert.

 

[todds112]

Cut in is 100-110 PSI. Cut out is 120-127 PSI. The govenor senses pressure from the main line to the wet resevoir. Signal lines run from the governor to the compressor unloader and the airdryer valve. Both primary and secondary have their own gauge.

If you just replaced the governor and the primary gauge is not showing a pressure loss before the compressor kicks on again, it could be the primary gauge is not showing correctly and there is a leak in the primary system allowing it to leak down to the cut in pressure.

OR

Looking at the P2P, if there is a leak before the check valve prior to the 150 PSI pressure relief valve and the compressor, it wouldn't show up on either gauge. The governor would detect the pressure loss, though and cause it to cut in. Area circled on the diagram:

 

[Tornadogt]

Put a pressure gauge inline between the compressor unloader and governor. Once the pressure reaches the set cut off point that line should charge with pressure equal to the cut off pressure.. (the gauge should read 0 pressure before cut off pressure is reached) the Unloader line (As well as the line to the dryer purge) should hold full line pressure until the main tank pressure drops below cut on pressure. At that point the unloader line should loose all pressure (gauge inline goes to 0) and the compressor should start pumping..


My guess is that as soon as the Unloader gets preasure it starts to bleed off and restarts the compresser within less than 1 min..

Cause: Leak in dryer purge/ Purge line OR Leak in Compressor unloader/ Compressor unloader Line.

Neither one is too hard to fix. Plug the Dryer purge line to eliminate it from the system if problem goes away, get a lower dryer rebuild kit or new dryer... If problem still exists remove the unloader line from the top of the compressor and blow air into the unloader. You should hear the unloader moving under pressure but NOT air leaking.. it should be a solid clunk when air is applyed with out an air leak... IF you hear air leaking at the unloader it is a small seal kit that can be gotten from Cummins..

Good luck let us know what you find..

 

[dawico]

My truck acts similiar (923a2). One easy thing to test is to spray soapy water on the top of the compressor (unloader). I noticed mine was leaking between the gasket and around the bolts when I primed it after replacing the fuel filters.

 

[Artisan]

I forgot, can the governor cut in pressure be adjusted down some? (Check TM). Also make sure there are no leaks anywhere.

If I remember correctly, when you adjust the governor you are
adjusting the governor CUT OUT pressure, from there the CUT IN
pressure is automatic and "about" 25% lower than the CUT OUT pressure.

Get the EXACT model # of your governor and get the manual for
it from the mfg. to prove me right, or wrong.

 

[M35A2-AZ]

I have a truck that was doing about the same thing and it turned out I had a some air leaks that the wet tanks supplies air to.

 

[Skullmaster]

Thanks for all the suggestions, I will be trouble shooting these ideas hopefully next week when the weather warms up, way to cold out to want to go out and work on the truck here in minnesota. I will report back with my findings when I do so

 

[plainside]

Did you find anything out now that we have warmer weather? I have the same issue, kicks back on the second the air dryer closes from exhausting.

 

[plainside]

I noticed mine leaks around the head gasket a bit, not a lot but some bubbles out there. That would not make the compressor kick on that fast though, shouldn't have anything to do with it? Did find a governor line leaking bit ( a steel one) but tightening it didnt do anything. not enough to hear but bubbles make it show, do you worry about that?

 

[Skullmaster]

i have not had a chance to go over mine yet, we just got nice weather this week so I have been working on some other projects, I hope to tackle this later in the week