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Gary R Coffman
 
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Default Old Sears Air Compressor - Help Please

On Wed, 13 Aug 2003 16:14:17 -0500, "EW" wrote:
My OLD 220 Volt Sears air compressor (model # 106.15378) with twin cylinders
recently quit being able to compress more than about 65 psi into the tank.
At that point, the motor still runs, the fan belt starts to squeal, and the
cylinders will no longer run. I can't even "turn" the flywheel by hand.
Lowering pressure a lot lets it run again.
I'm assuming something (reed valve??) is causing the high pressure air to
"work" against the cylinders so hard that they will simply not pump. (I
wonder if storing the compressor in my hot Texas shop -- 140 degrees in mid
PM -- contributed to this!)
Any ideas? "IF" it's a reed valve, is it accessible at the top of the
cylinder block? Is there a difference between the "input air" and output
air" reed valve? Can I fix a reed valve? ANY comments would help!!


Yeah, you probably have a broken output reed valve. That's letting one cylinder
pressurize the other when its piston is at the bottom of its travel. Effectively
the compressor is trying to be a two stage compressor, but the system isn't
designed for that. So when you hit 65 PSI, the second cylinder is actually
trying to pump 130 PSI, and it can't. The problem can't be the unloader
because the compressor starts and runs for a while before stalling. It can't
be a stuck check valve because some pressure builds in the tank.

The reed valves are mounted in a plate under the head. Generally there'll
be enough corrosion that you won't be able to remove and replace only one
reed valve. You'll have to replace the plate and valves as an assembly.

Gary