Air leaking

by Colin Lloyd
(Angus, Ont)

There is an air leak coming from the piston.


Can the piston rings be replaced on a Mastercraft 3 gallon compressor?

Comments for Air leaking

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May 25, 2017
Compressor leak fixed
by: Colin

Thank you for all your help with this. It was the check valve,,, Took it apart and inspected the valve and found that the plunger had turned sideways... Reset the plunger and reassembled the compressor and no more leak.

May 24, 2017
Leaking piston on Mastercraft
by: Bill

Ask yourself, Colin, if the compressor is off, where the air that is leaking from beside the piston is coming from?

It has to be the tank, as there is no other source.

How come air is leaking from the tank, back up the pump tube, to get out beside the piston?

That's a tank check valve that has failed.

Before you replace any rings, clean or replace the tank check valve. If that stops the leak, the piston rings may be fine, just sloppy, designed that way to not overcome the power of a fractional HP motor.

Let us know, please.

May 23, 2017
Reply to Piston leaking air
by: Colin

When I took the housing off, I could hear the air hissing by the piston rod. When I moved the piston the air leaked more. From that I had to assume it is the piston ring that is shot

May 22, 2017
Leaking Mastercraft air compressor
by: Bill

Hi Colin. How do you know the piston is leaking, or rather, where is the air leaking from, please?

While parts for this brand are scarce (really, almost non-existent) if it's really a piston ring that's leaking, removing the existing, measuring it carefully, and seeking a replacement from piston ring suppliers will result, I expect, in finding one.

I'd still like to know how you diagnosed this?

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