Air compressor fault

[Nufab]

Hey guys.. I've just signed up here after spending a while browsing the forums.

I'm currently restoring a mk1 Mini, which is my first in-depth restoration project. I have an Airmaster 8/65 compressor, which I bought from my mate's dad for £50. I have little idea of how old it is, but it seemed a good buy. It runs my air saw really well anyway, which I use a lot on the Mini.

Anyways.. a few weeks ago, I went to switch it on, and it seemed to stall the motor while powering up. I turned it off and on again, and it was fine. Yesterday I went to use it, and it stalled again when starting up. I turned it off then back on, and the motor made a humming noise, but wouldn't turn. It now won't turn on at all and appears completely dead.

I understand the basic principles of a compressor, but have no idea what might be wrong or how to fix it... any ideas would be very welcome, as I've come to rely on this bit of kit and don't want to spend £200+ on a new one!

 

[the snooper]

things to check are the delivery pipe pressure release valvle it should blow off when the compressor has filled and cut out also check the connections of the capacitor on the motor could have worked loose

 

[eil]

Drain the tank and warm up the compressor body with hot air gun or similar in this weather the oil gets quite thick, leave the tank open till the comp gets up to speed. I'm assuming you've got no heating in the garage.

 

[the snooper]

yes i agree they get very sluggish in this weather ive started the comp at work that way

 

[tigler]

Are you running it on an extension lead ?

 

[gordon stephenson]

Has the motor got a capacitor that might have gone bad?

 

[Nufab]

Yes, it is on an extension lead, but only 3m and its fully uncoiled. The motor does seem quite stiff to turn, but then I suppose it will when its compressing air and has oil in it.

There is a cylinder on the side of the motor, about 3" long by 1.5", which I'm guessing is probably the capacitor.. How can I test if this is knackered?

Due to the car project, I'm regularly cutting and griding metal.. could the dust from this cause problems? The compressor has a filter fitted, but would the dust affect the motor?

Also, does anyone know the spec of my compressor? I can't seem to find any manuals or details online.

 

[the snooper]

dont know what you mean by spec but the 8 will be 8cfm and 65 will be 65 litre tank
get a hot air gun and heat the compressor cylinder (not the tank) for 3 or 4 mins you may find it will start
mine struggles to start on a very cold day with a 3 horse motor try this before anything else

 

[pedrobedro]

It's from the Clarke airmaster range so they should have the specifications somewhere on the Machine Mart website or be able to tell you in one of their shops probably. They do an 8/64 which might be close on details.

 

[malcolm]

I had an 8/50 in the past. That would stall in the winter if I shut the compressor off on the wall rather than using the pressure release switch on the compressor (which was broken ).

Just a thought - you are using the on-off switch on the compressor? That releases pressure when you switch it off so the motor doesn't have so much to push against when you try to start it.

 

[tigler]

If the motor is stiff throughout a full revolution then that indicates a problem. Whether it's the motor or the pump is the next thing to determine. Check the air filter to see how dirty it is.

 

[Nufab]

Cheers guys. I do always switch it on and off with the pressure release switch, and I topped up the oil before I started using it. I'll check the filter and try heating the compressor and report back.

 

[jaykay]

hmm,too much oil???
warm it up as everyone is telling you.
still no go? remove belt,then see if motor or the pump is hard to turn over.

 

[Bsmith]

I recon the start capacitor would have burned out when the motor was making the humming noise most likely due to attempting to start on overload. My compressor will not start this time of year with over 50psi in the tank, so I have to manually use the isolater switch instead of leaving it to the pressure switch as it attempts to restart it at 80psi. Can't remember how to test a capacitor but any electrician will advise you. You actually are better to have a fuse or breaker somewhere in the supply to protect the capacitor.

 

[eil]

To properly test a capacitor you need a capacitor tester to obtain the capacitance reading, there are other tests you can do to see if its a dead one or not though, have a look through this
http://www.applianceaid.com/micro4.html

 

[Nufab]

Ok guys, thanks for the advice. The air compressor is in the garage, which is at my mum's house.. I'll be over there tomorrow so I'll strip it down and test it.

Is the capacitor absolutely necessary for the compressor to run, or is it just for extra power when it starts up? I'm just thinking that I could test everything out by shorting out the capacitor.

 

[pete3000]

don't short out the cap, it may have nasty consequences.

Yes it is needed to start the motor. The only other way is to spin it to start it which you've said is a no go as the spindle is stiff. I reckon it may need the brushes looking at or a new cap. Then a new motor maybe the next step.

Pete

 

[eil]

This is a direct drive type I think is it?, you might have two capacitors on it, at the moment your compressor doesn't run so what would you gain from by passing the capacitor. Like Pete says you need your caps for it to run