Blow-By

Blow-By Points : blow-by, problems in internal combustion engines, ic, engine Excessive “blow-by” combustion gases are allowed to escape past the piston rings on the power stroke, creating excessive crankcase pressure build up which in turn forces gases, oil vapors and oil through the breather system to be burned in the combustion chamber via the induction system. This excessive crankcase pressure will also actually force oil and oil vapors past the oil control and compression rings on the induction stroke especially under high manifold compression conditions. The amount of oil migration to the combustion chamber under these “blow-by” conditions is open to debate. Several experts I have spoken to nave contrary opinion on this problem.

“Blow-by” conditions can be caused by the following:
Piston rings not seating.
Glazed, worn or tapered cylinder/bores
Cylinder bore distortion
Broken piston rings
Excessive ring-end gaps
Misaligned connecting rods