High air pressure won't adjust.

[ldmack3]

Just put my dash panel in with new air gage, air hose to it and to the control of the front hubs. Started and at 60 PSI buzzer cut off. But the pressure continued tp build until it pegged above 120. Went to the TMs, bled the pressure down and adjusted governor as specified. Ended up turning the adjustment screw out (counterclockwise as specified) a total of 3 to 4 turns until it ran out of adjustment and the needle still pegs out.
Since the gage reads 60 when the low air buzzer cuts off I suspect it is correct. The old gage read 120 every time I ran it including earlier this week with the old parts still in. I'm not willing to pull the panel again to sub it in unless I have to.
Air governors are inexpensive, but before I replace it is there anything else I should look at/do? Seems strange this just suddenly started when I installed new parts.

 

[Menaces Nemesis]

Maybe you got a bad gauge? Got a shop compressor you could borrow a gauge from?... I'd check the system pressure with another gauge at the emergency glad hand, the supply stub by the interior passenger dash/kick panel, or you might be able to take a plug out of the air governor and spin the gauge right into the gov. itself.

 

[ldmack3]

Maybe you got a bad gauge? Got a shop compressor you could borrow a gauge from?... I'd check the system pressure with another gauge at the emergency glad hand, the supply stub by the interior passenger dash/kick panel, or you might be able to take a plug out of the air governor and spin the gauge right into the gov. itself.

I thought that but the buzzer cuts off at exactly 60 PSI on the new gage. I'll see what I can scrounge up. Compressor gage is internal to reg.
Thanks

 

[cattlerepairman]

Reminds me to tee in the 150psi safety blowoff valve. The Deuce compressor doesn't have one.

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[ldmack3]

Ok plumbed in a portable air tank with a 150psi limit. When it go to 130 I pulled the plug. Since I had already turned the governor down as far as it would go it' should have topped out before then. I can only guess the old gage was bad and I was running over pressurized.
Can this damage anything?

 

[davidb56]

there should be a relief valve on one of the air tanks. crawl under it and I think its on the front of one of the tanks. It should have a trip ring you can pull to make sure it isn't stuck closed.

 

[Menaces Nemesis]

Well then... I'd install a new gov.

 

[ldmack3]

Well then... I'd install a new gov.

It's on the way from Midwest. I'll also check the relief valve as suggested.

Thanks for the feedback everyone.

 

[cattlerepairman]

there should be a relief valve on one of the air tanks. crawl under it and I think its on the front of one of the tanks. It should have a trip ring you can pull to make sure it isn't stuck closed.

None on my truck. In case of governor or unloader failure it would continue to build pressure until the weakest point in the air system blew.

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[davidb56]

None on my truck. In case of governor or unloader failure it would continue to build pressure until the weakest point in the air system blew.

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You can "tee" one on your receiver (air tank) for 30$. Maybe someone did that on mine. BTW my air dryer has one built into it too.

 

[davidb56]

None on my truck. In case of governor or unloader failure it would continue to build pressure until the weakest point in the air system blew.

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If yours is missing: TM 9-2320-361-24P figure 87, part # 223444. its #6 on the illustration. I'd just plumb a aftermarket one in rather than pay $$$ for the "military" version

 

[cattlerepairman]

I have a standard 150 psi valve on the shelf. I have not plumbed it in, yet. Golly, I do not want to run out of Spring projects!!

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[Crf450x]

I see you already ordered a governor but for future reference you can check it easily by seeing if it’s letting air through to the unloader. If it is, the unloader isn’t working. If it’s not, check air pressure right at the governor. If you have full pressure there, the governor is bad.

 

[ldmack3]

I thought the unloader was built in. There is a port on the governor they say not to block so it can vent thee excess pressure.

 

[Crf450x]

I thought the unloader was built in. There is a port on the governor they say not to block so it can vent thee excess pressure.

The unloader valve is in the compressor head. When the air pressure gets to the set point, the governor lets air go to the unloader. While that’s open the compressor is just freewheeling. When the pressure falls back down, the governor vents the pressure going to the unloader so the compressor starts making air again.

 

[ldmack3]

A bit confusing but.. So the port on the governor that I'm not supposed to block is venting the control pressure going back to the compressor. So the governor really just controls the compressor, not directly regulating the system pressure. It is but by turning the compressor on and off. Right?
So I could have a bad compressor/unloader?

 

[Crf450x]

A bit confusing but.. So the port on the governor that I'm not supposed to block is venting the control pressure going back to the compressor. So the governor really just controls the compressor, not directly regulating the system pressure. It is but by turning the compressor on and off. Right?
So I could have a bad compressor/unloader?

Yep you got it. I’d say the governor is more likely to be the problem but yes it could be a bad unloader. It’s super easy to test it though. Just have to loosen a couple air lines.

 

[ldmack3]

Wow. Had no idea.

Thanks for the education.

 

[ldmack3]

New gov and all is well. It started hunting for the correct pressure and finally settled down to about 120.

 

[frank8003]

I put a gauge in my line of sight, teed off my tire filling manifold under right side of dash.
I eyed that gauge always as no air=difficult stop. I could see the air regulator functioning.
I had suggest installing this manifold to all to air up tires safely, hook it up and stay on other side of the truck.
It proved the in-dash air gauge and buzzer to be inaccurate.