Saftey valve on head "pops off" on Craftsman compressor

by Thommy
(MI)

Pump for Craftsman model 919.167810 compressor (Photo: www.amazon.com)

Pump for Craftsman model 919.167810 compressor (Photo: www.amazon.com)

I have an 80 gallon Craftsman compressor. Model 919.167810. I found that one of the valves had broken on the rear (exhaust) head during a routine check. I ordered a gasket kit and set of valves.


After reassembling everything and tightening to the proper specs the compressor builds pressure until about 70 psi is reached and then the saftey valve head pops off every second or so.

My compressor would normally reach about 130+ psi before the PRV would function shutting the compressor off. Now it will not build over 70 psi.

Is it possible I assembled something wrong or one of the new valves is hung up? I have not disassembled the front (intake) head yet to inspect that valving... Please help. Thanks!
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How are you doing, Thommy?

I suspect that your Craftsman 919.167810 is popping every few seconds due to pressure build up in the line between the two cylinders.

In the photo, the PRV you refer to is on the right cylinder.

When the air cannot flow properly, as the cylinder reciprocates, pressure in the head area exceeds the PRV setting.

That, or the PRV is failing. That isn't likely.

"Is it possible I assembled something wrong or one of the new valves is hung up?" Unfortunately, I think you've diagnosed this yourself. I suspect the answer to your question is yes.

Sorry,

Bill

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Dec 14, 2012
Thanks
by: Anonymous

Thanks Bill,

I found some fragment of the damaged valve in valve for the pressure cutoff switch. I thought I got it all out, but Im wondering if there may be a partial blockage in that copper line between the cylinders. I just removed it from the head I had to remove, I didnt blow it out or verify it was clear. I will have to disassemble it again it appears... Thanks
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You are welcome!

Bill

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craftsman runs but will not build pressure

Made in 2007, model number 921.153101 , 1 hp. , 3 gal. , 10.5 amp, 125 psi. runs but will not build pressure???? took pressure line off, plugged with finger and it cuts off.
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Hi Ernie...

See the troubleshooting section and follow the links to the page about reasons why an air compressor runs but doesn't build air pressure.

Some things to check, then post a comment here with an update and we'll press on.

Cheers,

Bill


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Craftsman air compressor ~ Purpose of the Pressure Relief Valve

by Don Bartelson
(Merritt Island, FL USA)

I have a 3-gallon 125 psi Craftsman air compressor Mod. 921.153101.

There is a small Pressur Relief valve mounted under the Pressure Switch. When the unit reaches its cut-out pressure, a little lever coming out of the bottom of the Pressure Switch pops over to hit a little needle pin sticking out of the Pressue Relief Valve, relieving a little "spit" of air pressure.

However, on my unit, the mounting for the Pressure Relief Valve is bent in such a manner that the little lever misses the needle pin that is sticking out of the valve, so no "spit".

What safety concern is not being performed on my unit? What's the purpose of the whole thing? Unit seems to work OK even though the valve doesn't relieve that little "spit" of pressure. DON

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Bill says...

Don, I guess what you are referring to is a pressure relief valve, as it does just that.

It's other name is Unloader Valve, and if you go to the site map page you can find the link and have a read of it.

Yes, it is important, and not having it working will create, I would think, some maintenance issues down the road as your system ages.

Cheers,

Bill

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30 gallon 5hp electric craftsman air compressor - starts to cut in and out and shuts off

by john
(des moines, ia)

The air compressor turns on briefly, starts to cut in and out and shuts off and won't build up more than about 20 psi before shutting off.

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Bill says...

Hi John.

The compressor cuts in at below 20 PSI and cuts out at 20 PSI or so?

This "screams" pressure switch to me. The "normal" cut in pressure is often in the 80+ PSI range, and the cut out is 120+ as a norm. That your compressor is cutting in below 20 PSI (had to be below as it shuts of at 20 PSI) says to me that the pressure switch really needs replacing.

Cheers,

Bill

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Aug 06, 2010
5hp craftsman compressor
by: MOOSE

my 5 hp craftsman does the same thing,it will run for a short time and then it slows way down then speeds up a little until it finally stops completely.when i disconnect the belt the elec motor seems to run fine.took the pressure valve out of tank and with the hose from the pump connected i ran the motor and air seems to be coming out of the little holes on the valve ok but it still slows down and finally stops the same as it did with it connected in the tank.i also took the elec motor apart and it looked fine inside,armature and windings looked good.i also listened to the pump side with a stethescope to see if i could hear any rod noise but nothing sounded like it was beating up the crank.

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