Oil in air tanks/ timing the air compressor on a M11

99 Volvo/ Cummins M11/ Super 10. Former Fed ex, now single axle hay/farm truck. 977k and appears to be the original compressor.

Truck was slow to build air on a 34 degree day so I went to drain water out of tanks and got a significant amount of motor oil out of it (a least a cup before I quit) so I’m pretty sure it’s compressor time. It built air once I ran it up to about 1200 rpm and did fine for the rest of the day maintaining 120psi. Does anyone have the service manual procedure for swapping the compressor or can you explain how to time the air compressor for the reinstall? We have a complete farm shop and do most of our own work, just can’t find anything on timing the compressor other than some on the internet say it’s necessary, some say it isn’t.

any thing else it could be other than the compressor? Anything else I need to do while I’m there?

thanks in advance for your response.

jay

 

Truck is used for hay and equipment hauling. It may see 3000 miles a year. Probably drain the tank every couple of months, maybe more if I’m hauling hay every weekend.
Jay