Cant turn down air pressure

[Jakelc15]

There its much to be learned from doghead as well. I've never seen him steer anyone in the wrong direction. There are many here that are a great asset to the hobby.

 

[Artisan]

FWIW; I carry a Governor for that day when I need it. I just located the Air Pressure Protection Valve #MBI KN31000 in the 5ton docs and I will be getting one of them to carry as well. I too used to come to this list looking for the easy answers, I am glad DG pushed me to attempt to get a command of the TM's. They ARE your friend. I try to now just ask q's when I am totally stumped. The google search tool works well too! Thanx for that!

 

[wheelspinner]

Here's my attempt to help this dead end thread.

The air governor on the firewall regulates when the compressor goes on and off. Cut in and cut out pressures. If you pressure is over 150 and the protection valve opens to bleed off air then your governor is bad. The governor is the only thing that tells the compressor to stop making air.
The ppv valve, as was explained earlier, separates the 2 air tanks. Tank 1 operates brakes, tank 2 has your accessories plumbed into it. At around 60 psi the valve should close, protecting the brake side from a leaking accessory. Any air from the compressor only goes into tank 1, until 60 psi is reached and the valve opens.
A faulty ppv will not make your pressure exceed the governor setting.

The governor is adjusted by removing the plastic dust cover on the end and tightening or loosening the nut. I think it takes a 1/2". In for more pressure. If the governor needs to be adjusted more than 5 - 10 psi it is probably bad and needs replacement. Most of the time when they go bad they stick in one position, usually all the way open or closed. If you start your truck and it barely builds any air, tap on the governor, it will usually start working again and you can drive your truck into the shop.
If you have to adjust it from 150 down to 130 where belongs, the governor is probably bad and in a week or two it will be regulating itself down to 110.

I hope this helps someone. I hate reading 50 pages of thread on a topic that has no resolution at the end. It better at least have pictures!

This is absolutely false! A bad PPV WILL cause the air to exceed the governed pressure as the governor signal is fed from the accessory air which is allowed to pressurize after the PPV is satisfied. I agree with complete closure, but it should be correct.

Sorry to resuurect an old thread, I found this while looking for something else.

 

[1 Patriot-of-many]

Here's my attempt to help this dead end thread.

The air governor on the firewall regulates when the compressor goes on and off. Cut in and cut out pressures. If you pressure is over 150 and the protection valve opens to bleed off air then your governor is bad. The governor is the only thing that tells the compressor to stop making air.
The ppv valve, as was explained earlier, separates the 2 air tanks. Tank 1 operates brakes, tank 2 has your accessories plumbed into it. At around 60 psi the valve should close, protecting the brake side from a leaking accessory. Any air from the compressor only goes into tank 1, until 60 psi is reached and the valve opens.
A faulty ppv will not make your pressure exceed the governor setting.

The governor is adjusted by removing the plastic dust cover on the end and tightening or loosening the nut. I think it takes a 1/2". In for more pressure. If the governor needs to be adjusted more than 5 - 10 psi it is probably bad and needs replacement. Most of the time when they go bad they stick in one position, usually all the way open or closed. If you start your truck and it barely builds any air, tap on the governor, it will usually start working again and you can drive your truck into the shop.
If you have to adjust it from 150 down to 130 where belongs, the governor is probably bad and in a week or two it will be regulating itself down to 110.

I hope this helps someone. I hate reading 50 pages of thread on a topic that has no resolution at the end. It better at least have pictures!

I've had a couple PPV that froze up, the pressure would continue to build till the safety valve on the tank would open. Replaced the PPV and it went back to normal operation.