Air Compressor Help

[Barrman]

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 won't really try to pull it in. I pulled the line going to the tanks and my thumb can block it off and not be pushed off. I am thinking bad compressor, but don't know about the firewall mounted regulator. Any ideas?

Thanks.

 

[acetomatoco]

Check the governor after you determine that the system is working and have checked all the valves and the glad hands in the rear to be sure they are closed..the one under the glove box can be open, too...Air tank drain open?? RAM

 

[Barrman]

I opened the tank drains just to see if air was getting to them. With one of them open and the rest of the system closed for 10 minutes of running, I had to feel with my hand for any air coming out because the pressure was so low that I couldn't hear it with the engine running. I'm just not getting any air compression at all. How does the firewall mounted regulator work on controling the compressor? I have one of the old water cooled compressors instead of the newer air cooled units.

 

[Floridianson]

The twin cyl. compressor has a low and high compression cyl. The twin cyl. compressor also has two lines. One of course is the pressure out line .
The other is the line that comes from the gov. When the gov. reaches the set amount it sends a signal pressure to the compressor valve and it opens up and relieves the pressure on the high cyl. side.
The single cyl. compressor does not have the line going back to compressor from the gov. The gov. just kicks out the over pressure.
What compressor do you have? Seems like even if the valve was stuck open it would pump up some. If you have the twin you could check the valve and see if it is stuck open.

 

[BFR]

can you hear the air compressor?

 

[Barrman]

2 cylinder Westinghouse water cooled air compressor. It has a water in, water out and air out all in what looks like 1/2" copper line. a 3/8" oil in line and another 3/8" air line that goes to the firewall mounted regulator. The intake port has a filter housing and a hose that goes to the engine air cleaner.

I removed the intake housing and can hear the compressor chugging away. I removed the big air out line and can hear the compressor chugging away. I just can't feel anything substantail when it comes to air moved. I removed the line from the regulator and felt nothing from either the line or the compressor.

I talked to the former owner last night. I have learned the less I say with him the better. He is one of those know it all types that will tell you everything you are doing is wrong. He was going on and on about how I should rebuild the engine before I even try to turn it over, rebuild the carb, etc... Even though he had done all of that but never started it in 1981. I didn't tell him the thing runs great and purrs like a large cat at idle. He also went on to tell me the compressor was completely gone through just like the engine before it sat for the last 25 years. Everything he has told me about the truck has turned out to be true. That is why I keep thinking I am missing something simple with the air compressor.

 

[m139h2otruck]

Just a couple of suggestions: 1) Spray some light oil into the intake of the compressor, like air tool oil. Won't hurt anything and if it pumps the oil will drop out in the air tanks and drain out with the water. Maybe the valves are stuck. 2) Is the head gasket blown? On the 5 ton gasser, the head gasket was leaking badly, and a rebuilt unit required us to return our core for the actual rebuild. I just made a gasket out of the correct material and bolted it back together. Worked great, pumps 100-110 psi fine and holds it. 3) Try disconnecting the gov. line and plugging it. DO NOT run the engine for long, just enough to check to see if it is making air. If it does, the gov. valve is NG or stuck.

 

[devilman96]

In reading what you have posted I am going to say bad / stuck reed valves in the compressor head...

 

[Barrman]

Thanks, I will try the air tool oil idea and see what happens.

 

[WillWagner]

You can also lighly tap on the governer. Sometimes after sitting a long time, they will stick. They are very easy to disassemble. Use o-ring lube or vaseline to re assemble it.

 

[JDToumanian]

The single cyl. compressor does not have the line going back to compressor from the gov. The gov. just kicks out the over pressure.

Maybe there's different different designs out there, but every single cylinder compressor I've seen had the unloader line running back to the air governor on the firewall. The connection where it goes is the hexagonal boss with the three vertical holes in it shown in the pic below. The center hole is usually threaded 1/4 MTP, for standard brass fittings and copper tube.

Could your compressor be missing something? Is that hole blocked off? I would think that a compressor constantly running at full output (safety valve blowing) would have a short life span.

Regards,
Jon

 

[Barrman]

I took some pictures and tried the oil in the intake trick last night. The oil didn't make any difference, but here are the pictures so you guys know what I am talking about.

I also couldn't find the oil feed line. Were these compressors internally oiled only?

 

[WillWagner]

See the 2, 7/8 inch or so bolt lookin' things to either side of the center raised housing? Those are the unloaders. They might be stuck in the loaded position, I believe that would be down. Dump all the air out of the system and take the caps off, careful, there's a spring under the caps. There's probably a bunch of goo or rust in there.

 

[WillWagner]

Maybe this will help,

http://www.tpub.com/basae/11011_files/image684.jpg

 

[Barrman]

Hey, thanks! I will go on a gunk hunt tonight.

 

[Duck]

Air compressor help

Symtoms indicate unloader valves are stuck.
The safe way to run test is disconect discharge line and regulater line
With truck running, purge with penetrating oil and blow gun from shop air

You'll probably still have to pull the valves
good luck

 

[Barrman]

RE: Air compressor help

Accoridng to the above linked diagram, the big nuts cover the discharge valves. I pulled them off tonght. The forward one had a broken spring. I shimed the rest of the spring with some washers and tried to put it together. I don't think those caps are supposed to be removed without pulling the unloader tower first. They wouldn't go back on. I turned .020 off the outside edge of each on the lathe and put them back on. Fired up the engine and had air. Thanks for the help gentlemen. I don't have a pressure gauge or any gauge for that matter right now, but I could open the passenger side glad hand valve at the rear and had lots of pressure after a few minutes of running. I didn't before. Plus, the compressor sounds like a compressor now and the intake tries to suck my finger in which wasn't the case before.

I will pull a spring off my parts truck over the weekend and get rid of the washers.

 

[gimpyrobb]

RE: Air compressor help

Good to hear Tim, Time for a test drive!

 

[Barrman]

RE: Air compressor help

Now that it works and I looked at it close enough to realize it has no engine supplied oiling. How the heck do I check, add, drain oil on this compressor? I don't won't to burn it up. Sorry for being such a "tech leach." Thanks.

 

[JasonS]

RE: Air compressor help

I believe that the supply and drain line are in the bracket that bolts to the block.