Compressor or governor sticky ?

[johan77]

Hi guys, i have an 1954 m108 with oa-331 gasoline engine. I have no air leaks, air is everywhere it should be, it also holds air for long time, however here is the issue :
The pressure only goes barely till 30psi so way to little, can it be that the governor is stuck somewhere so pressure cannot build up ? Or do i have a faulty air compressor ? Ps. The oily top cover on the compressor is penetrating oil to break free the bolts from the cover to eventually look at the compressor unload valve clearance.
I did not open the governor not yet, there is a filter element inside so worth to check since the truck was standing for 10+ years.
I will also fill the system trough the emergency gladhand with my home air compressor. The reading on the dash should read the pressure from my home compressor i hope, unless there is somewhere a non-return valve in the system...
Thanks

 

[Barrman]

I had a very similar issue when I first got my Gasser running 18 years ago. Here is a thread about it:

Air Compressor Help

I got my Gasser running this morning. It runs a lot better than I imagined. That OA331 has a lot of power. I am not getting any air pressure built up though. I removed the intake line and filter thinking it wasn't gettng any air. I can put my finger over the intake on the compressor and it...

www.steelsoldiers.com

My unloaded valve springs were broken.

Can you hear the governor cycle?

You have the newer version air regulator/governor. The older version was clam shell shaped. I am on the 3rd different new style governor on my multifuel Whistler. 1 would never let any pressure build. Another worked great until I was 100 miles from home. Then it decided 60 psi was my limit and clicked off and on about every 5 seconds all the way home. My current one lets me get over 90 psi but will eject air after the engine is off for around 10 minutes. Then the system slowly goes down to 0 psi from the governor.

I wrote all of that to say your issue seems to be compressor related since you hold pressure a long time. Check the unloader valve area and springs is my suggestion.

 

[johan77]

Goodmorning Barrman,
Thank you very much for shining a light where to serch.
The governor does not cycle, or makes any noise, So that will be the first thing i will open up and check.
Second i will also connect my home compressor to the emergency gladhand to fill the system up to 90psi and check again for any leaks, it does however holds air but 30 psi of air is not that super.
Isn't that unlogic ? If the unload valve springs are broken i would say it keeps building air pressure even with a working governor , being unable to release the excess amount of air. ?

I keep you posted , thank you verycmuch sir !!

 

[johan77]

I

I had a very similar issue when I first got my Gasser running 18 years ago. Here is a thread about it:

Air Compressor Help

I got my Gasser running this morning. It runs a lot better than I imagined. That OA331 has a lot of power. I am not getting any air pressure built up though. I removed the intake line and filter thinking it wasn't gettng any air. I can put my finger over the intake on the compressor and it...

www.steelsoldiers.com

My unloaded valve springs were broken.

Can you hear the governor cycle?

You have the newer version air regulator/governor. The older version was clam shell shaped. I am on the 3rd different new style governor on my multifuel Whistler. 1 would never let any pressure build. Another worked great until I was 100 miles from home. Then it decided 60 psi was my limit and clicked off and on about every 5 seconds all the way home. My current one lets me get over 90 psi but will eject air after the engine is off for around 10 minutes. Then the system slowly goes down to 0 psi from the governor.

I wrote all of that to say your issue seems to be compressor related since you hold pressure a long time. Check the unloader valve area and springs is my suggestion.

Just read your post.... yes yes and yes, that sounds very similar to my issue, only that i do feel some air pushing out the line leaving the compressor, and when opening the drain cock on the air tanks, it "blows" some air out but indeed not with a whole lot of force.
Also with the intake and filter removed i can easily block the intake hole, i do can hold the outlet on the compressor close with my thumb but i feel it pushing some air, not as strong as i should excpect from a compressor.
Thanks again sir !!!! It gives me again some hope that not much is wrong with it. I live in belgium and i can tell you that finding parts for the oa-331 is really not possible, let alone a new nos compressor for the gasoline engine.
My engine runs really really sweet, unbelievable after sitting outside for 10+ years.

 

[johan77]

I

Just read your post.... yes yes and yes, that sounds very similar to my issue, only that i do feel some air pushing out the line leaving the compressor, and when opening the drain cock on the air tanks, it "blows" some air out but indeed not with a whole lot of force.
Also with the intake and filter removed i can easily block the intake hole, i do can hold the outlet on the compressor close with my thumb but i feel it pushing some air, not as strong as i should excpect from a compressor.
Thanks again sir !!!! It gives me again some hope that not much is wrong with it. I live in belgium and i can tell you that finding parts for the oa-331 is really not possible, let alone a new nos compressor for the gasoline engine.
My engine runs really really sweet, unbelievable after sitting outside for 10+ years.

How did you manage to get those 2 valves back in ? Taking the top cover off like in the manual gives only access to the rocker arms for checking and adjusting the valve clearance .... i think