Compressor won't build up pressure above 20 lb.

by Terry
(Orange, Texas USA)

I have a Sears 1.5 hp 3 gallon air compressor (Model number 921.153101) that won't build up pressure past 20 lbs. I removed the check valve at the tank and it seem ok.

I also removed the head and inspected the reeds and they look ok. I squirted water around the head gasket and saw a few bubbles but not sure if it was a leak or just from the heat making the water bubble.

When you turn off the compressor I hear a slight noise (leak) but can't tell where it is coming from. Could it be from the pressure switch? If the pressure regulator isn't working properly can it cause the tank not to build up pressure?
Thanks,
Terry





Bill answers...

Hello Terry. Thanks for visiting and for writing in.

No, the pressure regulator won't affect the ability of the compressor to generate pressure. It only controls the downstream air pressure to your applications.

I've recently finished a summary page that details all of the reasons that I've been able to find for why a compressor will not build pressure past a certain point.

Here it is: Why compressors won't build pressure.

I hope this helps.

Cheers,

Bill




Comments for
Compressor won't build up pressure above 20 lb.

Click here to add your own comments

May 03, 2011
 Same problem.
by: H. Underwood

I had the same problem. Turns out the top most gasket failed.

Here's the symptoms - Motor runs great, no build up of pressure past 20 psi, air comes out of intake (filter housing) while in run mode.

No leaks when shut down - holds 20 psi great.

The key is - air coming out of intake during run mode.

Could have been a bad reed - but in my case, the top fiber gasket on the pressure plate had blew out where it seals the intake and the pressure side.

The good news - easy and cheap to fix with Sears replacement gasket set.

The bad news - The repair gasket blew the first time I installed it. Not a very strong gasket by the look and feel of it. In fact it didn't really look like the right material for the job.

The good news - I knew that a new gasket would fix the problem because I got up to 100 psi before failure.

More good news - I had some old gasket material. I used the new (bad) gasket as a template and cut a replacement by hand. Works like it should now.

My suggestion - Look for a bad gasket, order a replacement gasket kit from Sears ($5.99). Be prepared for it to fail, (I photo copied mine before I used them). If yours fails, go down to the auto parts store and get some sheet gasket material about .032" thick (tell the clerk what the application is). Hopes this helps someone.

________

Thanks. Good advice. Except, why buy the bum gasket? Use the old for the template and make your own. I'd opt for a high heat gasket, though.

Click here to add your own comments

Join in and write your own page! It's easy to do. How?
Simply click here to return to Compressor Will Not Build Pressure