Air Compressor Help

Ok we have an Older Air comperssor From 1961.
It has a Cast Iron Compresser.
Looks like the compressor is a DeVilbiss Model WP210B1009
And the Whole unit was built by Kargaro CO Model # MBI-KA-61-4474

When I was given to me I saw it work Saw it go all the way up to 80PSI and Shut off like any normal compresser would.
However now it will only go to 20PSI. I know it is not the guage as it will not fill a car tire.
We have Replaced the releif valve, the pumptroll, and had the Electric motor sent out the motor came back fine.
I bypassed the pumptroll and put power directly to the motor and it still shuts off at 20PSI.
When the compress reaches 17-18PSI you can hear it start to slow down.(any compressor I've ever heard runs strong till it reaches the pressure point) and when it hits 20Psi the motor can not turn the compressor over and you have to throw the switch to kill the power.
Since the motor tested fine, I think it is the compresser. but the compressor does not get hot. is it possible there is blockage in the lines? creates to much back feed to the compressor? does the compressor need rebuilt?


biran

I think you have a simple electrical supply problem.

Have you moved this compressor to a new location, or use different wiring for it, such as an extension cord?

Compressors need thick wires to let it run properly, like 10 gauge or 12 gauge. Also, avoid long extension cords and wires. The shorter the wire, the better.

If you use a thin extension cord, (ie 14 or 16 gauge) and especially a long extension cord, the motor will behave as you describe.

Also, is this a 220 volt compressor? If yes, are you using a 220 volt outlet, or a 110 volt outlet? 220 volt would be required if that's what its designed for.

Ok

Looks like the Rings are fine. I removed both exhaust valves and see no oil on the tops of the piston like the manual say you'd find if the rings were shot.
What I have found out though is this. when the tank is empty the Compressor is easy to turn over. After 1min 30sec or 20 psi the motor strugles and When I try to manualy turn the compressor over it take some doing. Like the compressor is building up pressure. Maybe a valve is not opening?

Brian

Thread moved to the appropriate forum:)

if it shuts of atomatically, wouldnt it be hooked up to a pressure/cutoff switch. sometimes these switches are adjustable(stud/nut/spring) check link v
http://www.grainger.com/Grainger/wwg/itemDetailsRender.shtml?xi=xi&ItemId=1613541521&ccitem=

if it shuts of atomatically, wouldnt it be hooked up to a pressure/cutoff switch. sometimes these switches are adjustable(stud/nut/spring) check link v
http://www.grainger.com/Grainger/wwg/itemDetailsRender.shtml?xi=xi&ItemId=1613541521&ccitem=


No it is not shutting off. we are turning it off. What we have found is the flywheel is very easy to turn over when there is no pressure. but once we run it and it starts to build pressure and the motor has trouble turn the flywheel we notcie that the flywheel is very dificult to turn over by hand.

Brian

Think you may have a reed valve sticking?

As noted above, pressure from the tank may be backing up into the compressor through a faulty valve.

Also IMO a 45 year old compressor tank may not be safe.
Compressors produce moisture (condensation ) that accumulates in the tank. Inevitably, tanks will rust out, especially if the tank has been neglected and not drained daily.

46 years of condensation may have rusted the inside of the tank and make it thinner and weaker. 90+ PSI builds up tremendous forces that can blow up a tank and possibly send lethal shrapnel around the room. People have been killed in the past by rusty pressure tanks exploding.

IMO get a new compressor, or at least a new tank. They are not expensive - compared to your life.