Originally Posted by
Ottawa John
Check your Pollution Control Valve. If it's stuck open, the car will be sucking oil into the cylinders through the MAF tube. If this is it, you'll need to replace the PCV and clean the MAF sensor. Not really a tough job, and the symptoms are much more serious in appearance than the actual problem is.
Normally good advise, John.
However, the M112 engine does not have a PCV valve, the left valve cover just has a tiny hole where the large tube connects prior to the throttle body, and another even smaller hole ( along with the right valve cover ) for the smaller hoses that connects post throttle body.
I once got the bright idea of removing and capping off the large hose - BAD IDEA.
The engine made some really strange noises that had me thinking bad water pump, although it continued to run OK.
I'm thinking maybe the OP has a burnt valve or something. He should do the dollar bill test ( or pound note test ) : with the car idling, slowly lower the bill down over the exhaust, if it sucks into the exhaust tip, then probably a burnt / sticking valve.