A friend gave me a used Sanborn 20 gal belt drive horizontal air compressor but no owners manual. There is no oil level sight window, only a small dip stick. My question is do I screw the dip stick in when checking the oil level or not.

Also, I have had some squealing at start-up on the compressor that gradually goes away. Any ideas on what could be causing this? At one point when the compressor had not been run in a few months it hummed for a little while before the pump stated moving. Wondering if this is related. I now start it more frequently to avoid this. There is currently enough oil in the pump to be in range on the dip stick when the stick is screwed in completely.

I would appreciate your help on these questions. Thanks

 

Screw the dipstick all the way in to check and the belt is either loose or worn.

 

Thanks. If the belt is loose, how do you tighten it?

 

Loosen the bolts holding the motor and tighten the tension bolts if it has them or use a bar to pry the motor away from the compressor.
Make sure the motor doesn't twist and put the two pulleys out of alignment

 

Thanks for your response and good information