Obsolete Part for Old Compressor

6 years 3 months ago #2491 by Gary
Obsolete Part for Old Compressor was created by Gary
I have a old (1973) Craftsman compressor (919.156780) that has an air leak on what they call a 1/4" coupling (part number SS-3211, item 61 on the parts list). This appears to be more than a coupling as it shuts off the compressor when it is at max pressure. The coupling works but it leaks and the compressor keeps cycling on and off due to the leak. Craftsman and other suppliers say this part is obsolete. Does anyone know the original manufacturer or a replacement?

The compress works just fine otherwise and I hate to get rid of it.

Thanks in advance.

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6 years 3 months ago #2493 by MTR-Admin
Replied by MTR-Admin on topic Obsolete Part for Old Compressor
Thanks for the post Gary,

What you have, most likely, is a defective tank Check Valve. This is item #67 on the breakdown. I don't believe it's available any longer but it may be something you can repair with replacing the part. I would remove the Check Valve from the tank and see if there is any debris holding it up. There could be some debris inside the valve which is not allowing it to seal shut when the units shuts off, therefore it's remaining open, allowing air to back-feed from the tank, through your airlines and leak out of the coupler you mention. A bad Check Valve is a very common problem and the symptom you're having with the unit certainly sounds like it's caused by a faulty Check Valve.

- MTR

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6 years 3 months ago #2494 by Gary
Replied by Gary on topic Obsolete Part for Old Compressor
Thank you for getting back to me. The check valve you mention, item 67, is not leaking and works fine (its on a 3/8" to 1/2" tube). It is item 61 that leaks. The parts list describes this part as a coupling but it is not. It has a coupling body style where a 1/4" steel tube connects at the top and the bottom seems sealed with a pin sticking out. This pin interfaces to the pressure switch mechanically hitting a lever shutting off the compressor. There may be a tiny o-ring or seal around the pin that is bad. The pin. is about 0.3 - 0.5 mm in diameter.

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6 years 3 months ago #2500 by Gary
Replied by Gary on topic Obsolete Part for Old Compressor
This is in response to my questions about the Craftsman compressor (919.156780) that has an air leak on what they call a 1/4" coupling (part number SS-3211, item 61 on the parts list). The attachments are pictures of what the part is. It connects at the on-off pressure switch and maybe an unload valve. It could be a mechanically activated check valve. When the tank reaches pressure the compressor shuts off and a lever actuates the pin on this "coupling".

Do you know of anything like this that I can use for a replacement? I have tried cleaning it and it still leaks. Can I replace the entire on-off pressure switch with one that has this built in?
Attachments:

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6 years 3 months ago #2504 by MTR-Admin
Replied by MTR-Admin on topic Obsolete Part for Old Compressor
Gary,
Did you do our check valve test to determine if the check valve is in fact good?
The part you describe is the schrader valve on the pressure switch. This is available, but 95% of the people that order this end up ordering a check valve.
Here is a video on how to test it first:

mastertoolrepair.com/howto-test-check-valve-p-22524.html

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