Air pressure release????

[emmado22]

All,

On my M35A2C, it builds up air pressure and mantains it well when running.. I dont know if it is supposed to "blow off" excess air at 120+ or not? I never hear a "PSSST" of air beng blown off after it has been running for any length of time.. Is that normal, or is some blow off valve stuck or???????

 

[m16ty]

My m35a2c doesn't blow off either. I can here a "click" through the firewall that I think is the sound of the governor kicking the compressor off. Just make sure you're not building over 120PSI.
I've been around alot of civilian trucks with air brakes and the only ones you hear "blowing off" is the ones that have air driers installed. It's acually the air drier you here blowing off to remove water from the system whenever the compressor stops pumping.

 

[WillWagner]

It won't blow off. It will just stop building PSI at around 90 PSI. Could go higher, depending on what the gov. is set at. Todays trucks cut out at around 120-130 PSI and cut in at around 85-90 PSI. 90 PSI is normal operating pressure for the deuce. It would be easy to add an air dryer if you wanna hear it pop off though. It would be kinda spensive.
HTH, Will

 

[renovate7]

The air pressure is adjusted by turning a screw (under a cap) or hex head on the drivers side of the regulator. I just turned mine down to 100psi from 120. This way I can tell, by looking at the gauge, if it sticks and the compressor doesn't shut off. The 20 manual. 8-47, says there is an "air sytem safety valve" (pressure release valve ?) down on the air tanks. With the engine running I'm not sure if you'd hear it if it vented. I can hear my regulator pop off every so often. If you have the hood open and are looking at it when it happens you can see the vapor venting.

 

[oifvet]

My m35a2c doesn't blow off either. I can here a "click" through the firewall that I think is the sound of the governor kicking the compressor off.

So that's what I've been hearing! I thought it was a bad thing.

 

[m16ty]

My m35a2c doesn't blow off either. I can here a "click" through the firewall that I think is the sound of the governor kicking the compressor off.

So that's what I've been hearing! I thought it was a bad thing.

Well I've watched the gauge and when it gets right on 120 (that's what the gov. is set at) I hear the "click" and the gauge stops moving. So I'm thinking that's what it is.