Hi,

There are often two reasons why this happens:

1. Problem with scavenge system
2. Wrong use of compressor / stop procedure.

For number 1: there is a hose that connects to a pipe that reaches to the bottom of the separator filter - please check it is installed correctly, and the hose and pipe are not blocked (you should be able to blow through it by mouth).

For number 2: always shut down the compressor with outlet valves closed. If you shut down the compressor with outlet valves open, oil will come out the next time it starts up.

Also, what are you using the compressor for? If you use it for blasting, this is a very common problem - the oil separating system can't handle the pulsating air (on-off-on-off) and oil will come out with the compressed air - the solution is to use an extra buffer tank to smooth out the pulsations/.

I have a book about portable diesel air compressors that you might be interested in - also, check out the diesel compressor section of this website.

Thanks,

Cas