M923A2 Air pressure tops @ 65 psi

[EnteJager]

Air pressure builds quickly to 65 psi quickly in both tanks and stops at 65 psi. Air starts leaking from the bottom of Air Governor on the passenger side of the governor and won't build above 65psi, if I bump up the RPM you can hear an increase in the volume of air leaking as the compressor makes more air. The Pressure Protection Valve cuts out the accessories as it is supposed to, so I am not getting the wipers, horn, ect.

Has anyone had this type of problem with the air gov before? Just asking before I change it. Pretty sure it is toast but figured I'd ask.

I have been in the 23-1 and the trouble shooting.

Thanks,
Dave

 

[wheelspinner]

Dave the PPV allows the accessory tank to be supplied which then allows the governor to be signaled from the accessory side of the system. It usually releases air to the accessory system at around 70-75 lbs indicated. If you have no horn or wipers, the governor is not involved; yet. This almost sounds like a defective unloader on the compressor. At this pressure highly doubt the AG or PPV. Check the troubleshoot for the compressor if it gets that deep. My computer is TU so I can't look.

 

[EnteJager]

Thanks WS, I understand the PPV and it is doing it's job because the air isn't getting above 65 psi so no accessories are powered. What has me is why the pressure on both gauges go to 65psi and then it starts venting air from the bottom of the air gov. Does the compressor unloader signal and dump at the air gov? I will figure this out!

 

[Suprman]

I had a similar problem not quite the same but its worth checking. My ppv was stuck open slightly so a little air was getting thru but not enough to run accessories. It was enough to confuse the governor and tell the compressor unloader to stop sending pressure. If it was me I would start by replacing the ppv it isnt expensive and they do go bad often. There are check valves before the tanks that go bad also. Is there a lot of moisture in the air system? You can disconnect the output of the air dryer and put a pressure guage on there it should run up to around 150psi and the safety on the air dryer should open. This will tell you if the compressor is working.
Will

 

[EnteJager]

I had a similar problem not quite the same but its worth checking. My ppv was stuck open slightly so a little air was getting thru but not enough to run accessories. It was enough to confuse the governor and tell the compressor unloader to stop sending pressure. If it was me I would start by replacing the ppv it isnt expensive and they do go bad often. There are check valves before the tanks that go bad also. Is there a lot of moisture in the air system? You can disconnect the output of the air dryer and put a pressure guage on there it should run up to around 150psi and the safety on the air dryer should open. This will tell you if the compressor is working.
Will

Before I start looking into the system further I need to know why the air gov is venting from the bottom once pressure hits 65psi (is this normal place to vent?) The amount of air venting increases with the increase of engine rpm and the increased air from the compressor.

 

[Suprman]

Does it sound like its venting thru lines or is it venting out the side of the governor. Air should not come out the governor. There are extra ports on the governor they are usually closed off with screw in plugs. The governor and ppv are inexpensive parts. If it were me I would just replace both, one at a time. If no change and you dont have any air leaks in the system then I would check the pressure coming out of the air dryer to see if the compressor is capable of making 150psi. I would unplug the ctis unit also the o rings in the valve body on the floor in the cab can go bad and air can leak out thru there but I dont think it would be enough to swamp the system.
Will

 

[doghead]

http://beamalarm.com/Documents/haldex_d2_governor_service_data.html

 

[EnteJager]

http://beamalarm.com/Documents/haldex_d2_governor_service_data.html

Either the bottom exhaust port is missing its screw in cap or the exhaust port failure to seat / o ring, Thanks superman and doghead! I'll post up what I find next week when I get to work on it.

 

[Moosemcnally]

Either the bottom exhaust port is missing its screw in cap or the exhaust port failure to seat / o ring, Thanks superman and doghead! I'll post up what I find next week when I get to work on it.

So what was your final outcome on this. My truck is doing the same exact thing. PPV valve?