When I removed my crossover pipe, there was some oil at the hose connection and the backing plate was pretty oily. All I see is an O-ring or rubber ring behind the backing plate of the compressor housing. Is that what keeps oil out of the compressor? How about the turbine side? Anyone have an exploded view of an H1C? Should I go ahead and rebuild it or.....

 

first check to see if there is any excessive play in the shaft, if not, check for proper crank case ventalation, and then be sure the turbo oil drain back is clear of any crud that could cause blockage.

 

There are seals on the shaft behind the compressor wheel.

In addition to what turbo-max said, check the air filter. A restriction there can pull oil over as well.

Holset has free pdf versions of the turbo rebuild manuals on their website.

 

Mine on the tractor had the oil return pluged up inside the turbo on the exhaust side by the oil slinger, pumped oil into exhuast like crazy. $80 kit and lots of cleaning and its like new again, not a real tough job to rebuild just need to make sure your shaft isn't worn out before you order you kit. If it has a big groove you might be better off buying another complete used one. Be sure that your inch pound torque wrench will click backwards, I had to go find one that did.