Craftsman 12 gal Twin Piston compressor!! Intake valve issue

by Cesar
(New York)

Hello all!!

I changed the gaskets of my great working compressor because it had leaks and of course taking a little while to reach its temp... The compressor quietly turns on and fills normally but i have noticed that when the pressure starts rising over 50 or 60 PSI i get a lot of air coming out through the intake flap valves! I carefully replaced everything and i rechecked the placement of the gaskets a few times...
If you can give me any ideas I will appreciate it.. Thank you all very much..






Bill thinks...

Hello Cesar:

One valve is for intake and the other should allow air to flow from the piston to the tank.

Did you replace the valves too? Sounds to me like it's time, if you didn't.

Bill

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Craftsman air compressor spitting oil out vent hole?

by Mike
(Muncie, IN)

Hello, I have an old Craftman air compressor model number 106.154581.

It is a pretty good compressor that I have reclaimed out of someones "don't need" pile of toys.

Something I can't figure out though is this little hole one the twin cylinder compressor unit. It is right on top of the section of the housing where the shaft comes out and attaches to the pulley. It spits oil...but not in a "blow by" pressure way, more like the shaft is "slinging" oil out the hole as it spins. I've thought about just sticking a screw in the hole but not sure if it is supposed to serve as a vent or something. There may possibly be a missing component that belongs there to. Either way, I have to figure out something. The hole is only about an 1/8" big. PLEASE HELP!






Bill says...

Why help, indeed? If the oil spitting out isn't a problem, and your compressor is running right, who cares?

Just kidding!

It's really hard to figure out without seeing it, Mike. Any chance you could send this in again, with a photo, showing the location of the hole?

The other think you could do right away is go to your plumbing store and pick up a 1/8" sintered brass vent plug. This will allow air in and out of the hole, but should reduce the amount of oil getting out. If the plumbing store hasn't got one, you need to go to a fluid power distributor and ask for a 1/8 brass muffler. It will do the same thing.

Of course, you need to check and make sure the hole is 1/8 NPT first.

Cheers,

Bill

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Oct 16, 2010
Same issue
by: Bill J.

I have the same thing happening with my craftsmen compressor. I picked it up used. It works fine but the mist of oil from the 1/8 hole where output shaft is concerns me thought there should be a filter or something? just wandered if you resolved this issue billch@yahoo.com

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Intercooler Safety Valve Lifting. Why?

by Rich Lathrop
(Hastings, NY, USA)

I have a 919.167802 Craftsman Professional Two stage air compressor (80 gal tank) and several days ago the Intercooler Safety Valve (First stage discharge relief valve) started popping open when tank pressure reached about 150 psi.

Pressure switch for the compressor is set at a cut-in of 140 psi and cut-out of 175 psi and working as expected.

The unit is not running past the cut-out pressure and not lifting the tank PRV.

I have since removed the intercooler safety valve and installed a pressure gauge in its place to monitor the pressure.

The intercooler safety is labeled "PV 4,5 BAR D=6,8 BREV". So the valve appears to be set for about 65 psi.

When I run the compressor with the gauge installed I see about 60 psi at cut-in and about 75 psi at cut-out with a needle fluctation of about 10 - 12 psi mostly to the low side of the reading.

Based on these readings it doesn't appear to be a problem with the safety valve lifting early. What could cause this problem and how do I fix?

____________________
Bill says...

If it's set to release at 5 bar (75 PSI) and it is releasing at that pressure, then it seems to be working correctly.

It's purpose is to relieve pressure when the components in the air circuit it is protecting are seeing higher than desired pressures.

I would think that a flow restriction in the line from the inter cooler to the second stage, or a valve problem in the second stage, may cause this.

I have no specific experience with diagnosing this sort of compressor fault, so now we both rely on readers to offers suggestions for you.

Cheers,

Bill



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Jun 03, 2011
Fixed problem
by: Rich Lathrop

I fixed the problem. The compressor now charges to cutout without lifting the intercooler safety valve.
Here's what I found. One of the second stage suction reed valves was hanging open. So on every second stage compression stroke, some second stage pressure was leaking back towards the first stage. It appears that over time the edge of the gasket between the suction and discharge valve plates had a piece dislodge and get between the reed valve and the valve plate preventing the valve from fully closing.
I replaced the head gaskets and valve plates and everything works fine now. Problem solved.

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craftsman runs tank seems to fill - need to replace gauge or look for other problem

by Tom
(Portland, OR)

1hp 3ga 125psi
runs tank seems to fill no leak noise when off. gauges are not working. unscrewed 2" 200psi gauge used can of air and needle moves. Do i need to replace gauge or look for other problem. Runs seems to fill tank no leak noise, but no air pressure indicated on gauge and no pressure build up at hose nozzle. But does dispense air when opening of tank valve. Thank you for your help.

_________________________
Bill says...

A tank or regulator gauge is a small maintenance cost item, and they do fail. So, if you buy another for the requisite $5-8, and it isn't the problem, keep the gauge as ultimately you will need it.

From the sounds of it you have a possible gauge issue, and the fact that you have no air out of your hose nozzle would suggest to me that the regulator pressure is turned to off.

Cheers,

Bill

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