Help with an air compressor

[hungrybare]

Just wondering if someone could help me with some questions on my air compressor? It is a 30 gallon craftsman (devilbiss) oiled. After it pumps up to 130 lbs. the unloader valve keeps leaking air, but I cannot find a check valve anywhere. Do all compressors require a check valve or what am I missing?
Thanx for any help !!!!!

 

[kenfain]

I can't say they all have a check valve. I'm certainly not an expert. However if it has an unloader. Wouldn't it have to have a check valve to keep pressure in the tank.

 

[hungrybare]

I would think it should have a check valve but it doesn't look like anything has been changed. Thanx !!!

 

[G_P]

Mine used a simple rubber ball and spring under the compression fitting between the pump and tank. I would have never found it except by accident.

Sent from my C5120 using Tapatalk 2

 

[highcarbon]

if it has an unloader it has to have a check valve to keep the air in the tank once the unloader relieves the static pressure off the head. Try tracing the line from the head to the tank- lots of times the check valve is an inline type and it might look like a bushing where the line is plumbed into the tank. Lots of them are made out of brass, so if you can take a scratch awl or something and scratch the paint off, you might find it. A magnet might also work, they are generally npt (national pipe thread) where they screw into the tank- might be stuck with carbon or gunk, might have a broken spring, bad disc, etc. Usually available at graingers if totally bad.

If I can help, let me know
Highcarbon

 

[j.c.whitney]

I think the unloader valve performs as a check valve for the tank as well as a way to bleed off the head pressure once the pump stops.

 

[RCStocker]

I think the unloader valve performs as a check valve for the tank as well as a way to bleed off the head pressure once the pump stops.

It does. I have seen many a check valve with a ring on it to pull. It can be both the un-loader and check valve. Check with sears parts to see if they have any parts. They have all the prints and parts list up on the web for free. Just look up Sears parts and you can find it. Others may carry it. Any check vale will work. You might need to bend a new tube but that is no big deal if you have all the right tube benders. It might be a 5/8" copper line. My better compressors have a lager fill line.

 

[kams1973]

Remove the compressor's discharge plumbing, and you will find the check valve. Check valves come in many varieties. Some double as an unloader and check valve...commonly known as load genies. Others have a port that the unloader plumbs into. Then you get into check valves for gas powered compressors that incorporate an unloader and a pilot valve.