Air compressor help please .

[Triggermortis]

The pistons and rings are like new having only been run for a few hours, the oil level hasn’t been overfilled

 

[Triggermortis]

Drop oil out and refill with a measured amount of new oil. Remove air filter. Remove fan cover from motor and spin fan by hand, turning over the piston slowly for a couple of revolutions. Cover back on, clean air filter if needed. Plug in and try.
If its been sat a while I'd also remove the tank drain plug and let it run for a couple of minutes to blow the tank out.
Hope this helps.

I’ll try this, could it be a one way valve stuck closed?

 

[Dogangun]

I’ll try this, could it be a one way valve stuck closed?

Possibly.

 

[Dogangun]

It could be the pressure control valve that's stuck.
I had the same issue with a spares or repair machine. I ran it as stated and got it working.
Hopefully you have the same luck.

 

[finnbear270]

Is your compressor fitted with a dipstick or just a plain plug?, either way it will have a vent somewhere's (Pinhole under thumb grip)

https://aeparts.co.uk/cdn/shop/products/FN012035000_318x.jpg?v=1602744116

 

[Triggermortis]

Drop oil out and refill with a measured amount of new oil. Remove air filter. Remove fan cover from motor and spin fan by hand, turning over the piston slowly for a couple of revolutions. Cover back on, clean air filter if needed. Plug in and try.
If its been sat a while I'd also remove the tank drain plug and let it run for a couple of minutes to blow the tank out.
Hope this helps.

Well !!!!
I said in post #21 that the oil hadn’t been overfilled
I hadn’t done it and the feller who borrowed it had no reason to but when all that is likely has been ruled out the unlikely should be investigated.
I drained the oil, filled to the top of the tale tell glass, and yes, I still had a pint of oil left, started it up and hey presto works perfect
Thanks dogandgun
Triggermortis