Compressor problem

[Greeves250]

I have just got together a sand blasting plant and running into problems with the compressor. It's a 50 or so year-old two pot compressor with a big single phase motor. After about 10 mins of running the belt slips as the compressor becomes harder to turn and had to pull the switch to stop the belt from slipping and the motor from baulking. Would old oil give rise to this kind of issue?. It ran the tank up to 100psi twice before these issues arose. Hasn't been used previously in 7 years.

 

[shenion]

When is the last time you changed the oil?

Could be the bearings are gunked up. New oil will probably help.

If it hasn't been used in a long time, i'd definitely change the oil.

 

[rtbcomp]

Are you using air or just filling the tank?

 

[jaykay]

i have in the past used parrafin to clean internals.
put cpl of pints in leave it for awhile(1/2hr)run it for 30 secs a few times.then empry it all out.and re oil.worked a treat for clean it out.

 

[Greeves250]

Heh thanks for the replies. The oil is clear gold but smells like its been in there for decades.

 

[Greeves250]

Hi all
Drained all the old syrupy oil out of the compressor and cleaned the 'sump' area with some white spirit so there was virtually no trace of the stuff left. With new 20w oil it ran up fine but started to drag again at 50psi - exactly the same as before so I don't think that the old oil could have been the issue this time. Could it be something else?. Incidentally the pressure switch pastil looks very ancient - is it supposed to be rubber or a harder material?. I'm pretty desperate as a mate is waiting for some steel to be done.