[SOLVED] 1997 M1088 pressure release valve at 30psi?

[Ronmar]

Ok, maybe some clarification is in order. There are 2 valves on the air dryer. One is a safety relief valve. On the original dryers it is on the top(i‘m pointing at it in the pic), not sure where it is on the Haldex units. Like a popit type safety on any air compressor, under normal conditions it should not ever be venting air as it is there to keep from blowing something up if the governor sticks/fails. When the compressor is on line, you can lift/wiggle the knob in the pic and get air to vent. When the compressor is offline, the dryer has been purged and you wont get any air out of it...

the second valve is the purge valve. there are 2 lines running to the governor. One from the wet tank, one from the air dryer. Every time the governor reaches its set pressure sensed in the wet tank and unloads/shuts off the compressor, it sends air down that purge line to the dryer which causes the dryer to vent its internal air up to the check valve At the top outlet port. This causes a Puff of air out the bottom port Where the valve is located and where the water that coalesced from the air has collected, venting that water to the atmosphere. The dryer purges every time the compressor reaches the governor set pressure. The frequency at which this happens depends upon how much air you are using/how often the compressor cycles on and off...

Your governor should be set at 120-125 PSI measured at the wet tank. The rig with the gauge and blowgun is handy for checking/setting it. It must go over 115-117 PSI to close the CTIS pressure switch on the wet tank otherwise CTIS wont function...

 

[Oski1042]

So bringing our new (to us) M1083 home the other day, the purge valve on the dryer (old style) stuck open. Made it home ... with just enough air in the tanks. The next day when I took off the "snorkel" (which obviously needs to be replaced) I discovered what appears to be an adjustment bolt in the middle of the purge valve. Question #1 ... does this adjust the resistance of the purge valve? Question #2 .... does anyone have a Haldex number for the snorkel valve in the photo?

This winter I plan to replace the original air dryer with the new version. In the meantime ... I would like to know more about this unit. Thanks!

 

[coachgeo]

So bringing our new (to us) M1083 home the other day, the purge valve on the dryer (old style) stuck open....... I would like to know more about this unit. Thanks!

that is a duck bill not a valve unless your speaking of parts not pictured. All that rubber piece does is keep out dust etc.

sounds like you need to start your own thread on your issues. May/may not be related to the issues discussed in this thread.... thus would hijack it.

 

[ke6rwj]

Ok, maybe some clarification is in order. There are 2 valves on the air dryer. One is a safety relief valve. On the original dryers it is on the top(i‘m pointing at it in the pic), not sure where it is on the Haldex units. Like a popit type safety on any air compressor, under normal conditions it should not ever be venting air as it is there to keep from blowing something up if the governor sticks/fails. When the compressor is on line, you can lift/wiggle the knob in the pic and get air to vent. When the compressor is offline, the dryer has been purged and you wont get any air out of it...

the second valve is the purge valve. there are 2 lines running to the governor. One from the wet tank, one from the air dryer. Every time the governor reaches its set pressure sensed in the wet tank and unloads/shuts off the compressor, it sends a shot of air down that purge line to the dryer which causes the dryer to vent its internal air and the air in the lines out to the wet tank check valve. This causes a Puff of air out the bottom port Where the valve is located and where the water that coalesced from the air has collected, venting that water to the atmosphere. The dryer purges every time the compressor reaches the governor set pressure. The frequency at which this happens depends upon how much air you are using/how often the compressor cycles on and off...

Your governor should be set at 120-125 PSI measured at the wet tank. The rig with the gauge and blowgun is handy for checking/setting it. It must go over 115-117 PSI to close the CTIS pressure switch on the wet tank otherwise CTIS wont function...

View attachment 809177

thanks for the details ronmar. i understand more now. i dug up a pressure guage today so ill check the pressure on the wet tank and see if the ctis switch is working...

sounds like every thing else is as it should be... ill close this thread and start another if more issues come up.

thanks a bunch to everyone who helped out!!

chris in bama

 

[Ronmar]

So bringing our new (to us) M1083 home the other day, the purge valve on the dryer (old style) stuck open. Made it home ... with just enough air in the tanks. The next day when I took off the "snorkel" (which obviously needs to be replaced) I discovered what appears to be an adjustment bolt in the middle of the purge valve. Question #1 ... does this adjust the resistance of the purge valve? Question #2 .... does anyone have a Haldex number for the snorkel valve in the photo?

This winter I plan to replace the original air dryer with the new version. In the meantime ... I would like to know more about this unit. Thanks!

There is no adjustment for the purge valve it is simply a sliding core that receives air from the governor to activate and purge the dryer cannister. It could be that ithas some crap init and is stuck... I did a utube video on overhauling the dryer media but did not really cover that valve... as Coach said, probably should start another thread...

 

[Oski1042]

Got it ... thanks. No hijacking intended ... but you answered my question.
PS: Enjoyed the video!

 

[simp5782]

Air pressure gauges should read 120psi to 130psi depending on what your governor is set at. With a 120psi setting the cut in is 105psi when the governor tells the compressor to come on. If you have an air dryer that purges every minute to 10 minutes then you have leaks you need to address.

 

[ke6rwj]

An update on this issue... Since getting the pressures up, I've been running it around the farm and was able to get the truck under the M373 trailer we have. We needed to get the truck underneath the trailer since its landing legs are not functional and missing critical parts... We bought a new set of military legs that will actually work better for this truck.. if you look closely at the image you can see the problem with the legs...

I've since discovered that the right, rear, rear brake chamber is leaking on the closest to the center of the truck. Other than that its really doing well..

thanks to all for the assistance...

 

[Asymair95]

An update on this issue... Since getting the pressures up, I've been running it around the farm and was able to get the truck under the M373 trailer we have. We needed to get the truck underneath the trailer since its landing legs are not functional and missing critical parts... We bought a new set of military legs that will actually work better for this truck.. if you look closely at the image you can see the problem with the legs...

I've since discovered that the right, rear, rear brake chamber is leaking on the closest to the center of the truck. Other than that its really doing well..

thanks to all for the assistance...

Check for mud nests in your brake vent lines. Not sure where they are on your truck, but on my 1078 they are right above the axle. I had mud in mine causing leaks in my brake cans.

 

[ke6rwj]

Check for mud nests in your brake vent lines. Not sure where they are on your truck, but on my 1078 they are right above the axle. I had mud in mine causing leaks in my brake cans.

View attachment 810924

Good hint, mud daubers here are a force to be reckoned with... they get in everything... ill def check these....

 

[JD4044M]

It is normal to blow off on the Dryer off and on. I hate those mud wasps they fill in holes on everything around here. I will haft to put some mesh screen in that hole on mine to stop them from filling it up like they do in all the ground prong holes in the plugs in my shop, fuel hose etc!