So I have a 2001 Cummins HO that is pouring oil out of the drivers side of the engine. I have traced the leak down to the oil line running from the block to the bottom of the vacuum pump. I replaced the fitting into the block and the oil line and the oil leak continues. I then thought maybe the vacuum pump was starting to go and was causing the line to build too much pressure. I checked the vacuum and it was pulling 28 inches of mercury so it seems fine. I'm not sure if the engine is over-pressuring or one of the seals has gone bad in the vacuum pump. The pump itself does not appear to be leaking but the line is dumping oil. Any help would be much appreciated.

 

Oil leak at the vacuum pump is usually due to bad seals in the vacuum pump to power steering pump adapter. If you have a local Cummins shop you can get the seal kit cheap. I think I paid $10 for mine but that was about 3 years ago.

 

I second that. My truck had the same issue. Tore the assembly apart. Replaced seals. Worked great.