Speedaire 3Z427 - Air leak at pressure switch

by Terry
(Ottawa, Ontario, Canada)





I have an old compressor, Speedaire 3Z427.


The compressor cuts in at 70 and cuts outs at 110. When it cuts out, there is an air leak at the base of the pressure control valve. Once the pressure drops to around 100 the leak seems to stop.

Reading your web site points towards a dirty or faulty check valve. Darned if I can find the check valve. And there doesn't seem to be a pressure relief valve.

Can you look at the attached pictures and give me some guidance on fixing this air leak. Can I add a pressure relief valve if there isn't one?

Thanks
Terry
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Terry, thanks for the photos. That helps me understand more clearly the issue. Typically, the check valve is contained in the fitting where the line from the pump head enters the tank. And typically, part of that fitting contains a air line port that is plumbed over to the pressure switch. When the switch trips to off, the check valve in the tank fitting keeps the air in the tank, and the air over the piston flows down the line to the tank fitting, and then bleeds out the line from that fitting that is plumbed over to the pressure switch and the unloader valve. While this fitting lacks the line over to the pressure switch, I wonder if it contains the unloader valve? When the pump stops, if there is a valve in there, it could open to dump the over-the-piston-air right there?

In the second photo, the one with the bubble, the only supply to the switch is the pipe upon which it sits. That being the case, and there is no check valve related to the operation of this switch, then you must have a diaphragm or seal leak in the switch for air to be leaking there.

Cheers,

Bill




Comments for Speedaire 3Z427 - Air leak at pressure switch

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Apr 30, 2012
leak fixed
by: Terry

Bill, you were right about my leak being caused by a seal problem. I disassembled the pressure switch, cleaned up the mating surface for the seal, lubed it and reinstalled. Problem solved.

Thanks for your help and I'm sorry I didn't respond sooner.
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No problem. Glad it worked.

B.

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Auto drain runs all the time on wd63

by Wayne
(RTP, NC)

How do You repair / adjust the auto drain on a wd63? It is venting air all the time. I can disconnect the small line coming from the pressure switch to the diapragm and it stop, telling me the diaphragm is ok.
Thanks,
Wayne

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speedaire #3Z3558 pump knocking

by mike fisher
(redding,ca)

got 4 free ,and it runs but old owner says it knocks on pump for years,its a speedaire #3Z3558 and pump is 2Z499A.thanks 4 help,mike

Comments for speedaire #3Z3558 pump knocking

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Apr 04, 2014
Try the easy stuff first.
by: Paul

I bought an old Campbell Hausfeld similar to your Speedaire that had a knock which the previous owner thought was a rod going out. I tightened the flywheel and the knock went away. Hope you get lucky like I did.

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speedaire 4z492 leaking air

by Jim
(Massachusetts)

type of relief valve

type of relief valve

I have a 5hp and the pressure relief valve leaks the pressure shut off switch leaks and what type of oil do i need the model# is speedaire 4z492 Also the small 5/16 line that runs from the top of the head to the cover of the crank leaks water as it's running. I basically need some direction to take care of these issues and i have a small garage that i use to maintain a one truck trucking company changing tires,running air tools on occasions
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Jim, the photo is good, but I have no idea what it is a picture of.

If your PRV is leaking, then it needs replacing.

If by the pressure shut off switch you mean what I call the Pressure Switch, before you replace it, remove, clean and replace the tank check valve and see if that resolves the issue.

Regarding compressor oil, see that page linked from the site map Oil Issues.

"Also the small 5/16 line that runs from the top of the head to the cover of the crank leaks water as it's running" and, sorry, I don't know what this is.

Others might, and I hope they add a comment.

Cheers,

Bill



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