Strange compressor problem.

[jim painter]

Well not a problem as such, its more of an annoyance really. I have an old sipair compressor. It has a 200ltr tank and a 3hp motor. The problem is that the compressor will fire up as and when needed without problems but it gets to a certain point and then it slows right down while pumping to the point of almost stopping but after 20-30 seconds it will slowly pick up again. It does it 80% of the time. I did notice with my 20 gallon pot blaster I was getting a lot of water in both water traps (1 on the compressor and one on the blaster) but that could just be because it was running a while. It does get drained regular i.e. before and after use and in between if required. The only other thing I have noticed is there seems to be something bubbling from between the cylinder and head on the pump itself. Is there meant to be a gasket there or is it just pressed together when bolted down.

Thanks for help in advance

 

[rtbcomp]

There may be a gasket or some copper rings to seal the joint. It won't be metal to metal.

Does it bubble all the time or just when the pump slows down?

Sounds to me like the outlet valve or the non return valve on the tank is sticking closed, allowing pressure to build up in the pump, thus loading the motor.

Does it reach its switch-off point OK and what pressure does the tank reach?

 

[shenion]

My compressor was taking longer to fill the tank. I found the head bolts were all loose.

They are not real tight as they are into the aluminum block. You may want to check yours but be careful to not strip them.

 

[jim painter]

It reaches the cut off point ok, if i recall its about 120 psi cut off, but can be adjusted.
Maybe its just a case of stripping and cleaning. I will check the head bolts as well.
Thanks

 

[rtbcomp]

Check the belt tension as well, cheap and easy!

 

[brightspark]

Check the belt tension as well, cheap and easy!

as said the belt most probably causing it to puls.e its either loose or worn even perished tighten it and use belt dresing if its slipping

 

[tigler]

A friend had a similar problem a while back, I eventually discovered the motor was siezing up !

 

[jim painter]

I will check everything as suggested. It looks like it had a new motor not long before I got it. Thanks for all the advice.

 

[the snooper]

id go for belt slipping as a start point after 20 or 30 seconds of belt slipping, the belt and pullys will heat up with friction and start to grip again