Two Stage Compressor Help/Troubleshooting

[snpower]

I picked up a golden oldie a month ago locally, from a really good guy.

It is an old sears two stage 30 gallon unit. Last week while it was running I noticed the rythmic "put put" sound of the compressor had more or less stopped. Pressure was at 150psi but after the tank went down I could no longer get the unit to produce any pressure whatsoever.

I removed the cylinder head and found two of the reed/flapper valves had broken from rust. I was able to source those and today I installed them along with a new gasket and belt for good measure. While I was waiting I rotated the compressor by hand and did not hear or see anything that was concerning. The unit sounds normal now but... no pressure whatsoever. Everything is tight, and I do not hear any leaking. The only thing I have noticed by chance is that air seems to be coming OUT of the cylinder head cover through the air filter instead of going IN. Duh. What could I have done wrong, or what should I be checking at this point? IMG 2487 shoes what I found - the broken parts.

 

[dstig1]

Sounds like a bad check valve.

 

[SPYDERLK]

I picked up a golden oldie a month ago locally, from a really good guy.

It is an old sears two stage 30 gallon unit. Last week while it was running I noticed the rythmic "put put" sound of the compressor had more or less stopped. Pressure was at 150psi but after the tank went down I could no longer get the unit to produce any pressure whatsoever.

I removed the cylinder head and found two of the reed/flapper valves had broken from rust. I was able to source those and today I installed them along with a new gasket and belt for good measure. While I was waiting I rotated the compressor by hand and did not hear or see anything that was concerning. The unit sounds normal now but... no pressure whatsoever. Everything is tight, and I do not hear any leaking. The only thing I have noticed by chance is that air seems to be coming OUT of the cylinder head cover through the air filter instead of going IN. Duh. What could I have done wrong, or what should I be checking at this point? IMG 2487 shoes what I found - the broken parts.

Have you put the head on backwards?

 

[snpower]

Have you put the head on backwards?

No... the outputs would not line up if that were the case.

 

[snpower]

Sounds like a bad check valve.

Interesting. Hope not. So the check valve went at the same time the reed valves did?

 

[ponytug]

Interesting. Hope not. So the check valve went at the same time the reed valves did?

It seems to me that there was a fair amount of rust in your compressor head and check valves. If some of the rust/debris went downstream, it easily could have plugged the check valve open, or damaged it. So, yes, it is quite possible that it died at the same time. Given the state of the head and check valves, a new one probably isn't a bad idea.

All the best, Peter

 

[snpower]

So I pulled the check valve. It looks good and the parts move, accordingly.

What I did realize is that the gasket I got is not exactly the same shape - does not cover the same areas - as the one I removed. I installed the valve plate WITHOUT any gasket and the compressor built up air to 50 psi. There was good suction into the air filter. Gasket reinstalled - and air is exiting the top of the compressor through the air filter again. A clue in the mystery, perhaps?

The belt needs fine tune adjusting, I know this - but this was a good sign that the check valve is working ok (I think?). The tank is holding at 50psi.

I am not sure if I can get that exact gasket or if I could fashion one from something... ?

As always I appreciate the input from everyone.

 

[SPYDERLK]

No... the outputs would not line up if that were the case.

Good. Every valve in the head is a check valve. The compressor should pump if they are in correctly. An external check is only needed when the compressor is off. Are you sure every head valve is installed correctly?

 

[SPYDERLK]

Ah. I see you have found the problem. ... BTW, that is a 2 cylinder single stage compressor.

 

[snpower]

Ah. I see you have found the problem. ... BTW, that is a 2 cylinder single stage compressor.

I was just seeing if you were paying attention

Thanks for the correction!

 

[snpower]

Ok I am back in business. I picked up a FEL PRO gasket making kit this morning and made a new gasket for the valve plate. The gasket I received was incorrect. Everything is working as intended now!

 

[ponytug]

I'm glad to hear it was a straightforward fix!

All the best, Peter

 

[rontaki]

Many moons ago I bought an old, similar compressor that needed new reed valves very similar to what the pictures show. I had a long feeler gauge that was thin enough to make new reeds out of. I used it for msny years until the tank rusted through, even though I always bled the condensate after use. Upon taking it apart to attempt repair, I found the power cord wires had missing insulation where they entered the pressure switch. Looked like it had been that way for a while, just lucky I didn't get zapped!

 

[Topzide]

This is the exact reason I have hasket material on the shelf! A ball peen hammer to tap gasket out, cut outlines and the use hole punch set for bolt holes. Have exhaust gasket also!