Blowby is cylinder pressure getting into the crankcase past the pistons and rings, that's why its coming out of the vents for the engine. When you have stuff coming out the tailpipe its being burned in the combustion chamber and then exits through the exhaust valve and out the tail pipe.
Jerry, please fill in anything I missed with my description above.
Last edited by don stocker; 01/06/2015 3:33 PM. Reason: added line
