Piston Ring Deposits When Using Vegetable Oil as a Fuel

This paper documents the presence of piston ring deposits responsible for sticking piston rings in the diesel engine when using a vegetable oil-diesel fuel blend. It was found that piston ring immobilization is caused by carbon buildup on the combustion chamber side of the rings and in the annular space behind the rings. The carbon buildup is postulated to be the result of a polymerization growth process on preferred metallic surfaces. Most of the growth takes place on the relatively more stationary piston groove rather than on the ring. Carbon buildup preference was found for aluminum rather than cast iron at a common junction of the two metals. Possible solutions to these major problems are summarized.