Air compressor help please .

[Triggermortis]

I have a 50L compressor at home that has paved up working, when you switch on the power it just buzzes and the motor won’t start, the motor and pump turn freely by hand, any help greatly appreciated
Triggermortis

 

[takbok]

Maybe faulty capacitor?

single phase motor not starting- capacitor?

Help out a electrical idiot here, please. The bandsaw motor went bad- was running fine, then started real weak, shut it down and tried to restart and it just hums. 2hp, 120/240v, single phase. Has one start capacitor. Motor is wired 240, but the start capacitor is marked 110V. It has been...

www.practicalmachinist.com

 

[Jimboblincs2]

As above starter capacitor, should be a cheap fix.

 

[Cyres]

If its the capacitor CPL Farnell is a good place to source one. I got some for my cooker extractor hood. Postage was more than the product and miles cheaper than a spare from e spares.
D

 

[DavyG]

Replace this…

 

[Triggermortis]

Many thanks
So, if we assume it is the capacitor how do I test it then safely remove it please?
Triggermortis

 

[petlowe]

Many thanks
So, if we assume it is the capacitor how do I test it then safely remove it please?
Triggermortis

Unplugging it from mains power would be a good start

Pull it, read the spec, find a new one of same spec, plug it in and if you got the orientation right it won't go pop, if it goes pop, it's quite loud and you get a nice burnt electrics smell and the chance to start over.
Been there done that...

 

[Triggermortis]

So…
Put a meter on it, got a reading of 00.08m/v, so I’ve removed the capacitor, when you say of the same value, could you advise please

 

[Swedish]

Models that the part 'Universal 55UF/MFD AC Motor Start Capacitor 450v' fits

www.yourspares.co.uk

 

[Jon2712]

It’s tha Uf reading your after. Tester wants to be on micro farads. Looks like either 5.5 Uf or 55Uf can’t quite tell. But going by you pic the bubble in the plastic and the lid lifting near the cable are a sure sign you need a new one.

 

[Triggermortis]

I recon you’re right Jon
Thank you Swedish , top man

 

[ejg]

I got a spare in our farm shop in the village last time we lost one.
Edi

 

[Triggermortis]

Right….
So I’ve sourced a capacitor and fitted it, started up straight away, job done , or so I thought , after 20 seconds it pumped the oil out of the filler ( black tube, red top on left side in photo) I took the head off and the pistons/bore are mint as in this has only been run for a hand full of hours , any ideas please?
Triggermortis

 

[finnbear270]

Blocked sump breather?

 

[Triggermortis]

The compressor is electric, I was thinking there must be some sort of one way valve from the unit to the tank that is letting air leak back into the compressor on the induction stroke of the pistons?
Triggermortis

 

[ciscokid]

Is the motor spinning in the correct direction? Is it spinning the same direction as before the capacitor replacement? However with a compressor does it make any difference?

 

[Triggermortis]

Good question!
Yes it is spinning in the right direction.

 

[Len the dog]

It sounds to me like the piston rings are passing and allowing compressed air into the crank casing, this will act like a coffee percolator and force the oil level down and back up the filler tube. That could just be new piston rings or it could be worn bores.
Possibly it could just be that there is too much oil in the crank case, if the pump is expected to pass a little air on the compression stroke then it would just vent through the crank case breather/filler pipe, but if the oil level is too high then you will get the percolator effect where the oil level is driven down until the surface level reaches the open end of the filler pipe and allows the air to escape.

 

[Mike L]

Sounds like too much oil in the reservoir to me,

 

[Dogangun]

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.