I have searched with no luck.

What causes blow by? I see people talking about it on here and I can't remember the cause. Any other info on it is appreciated.

Thanks

 

Blow by is a result of piston ring sealing. Basicly when the piston is on the compression stroke a percentage of the compression bypasses the ring seal and is dicharged into the crankcase. As the rings wear the percentage of blow by increases.

 

how much blow by is considered excessive? i could possibly be looking at buying another truck in the near future andwould like to know what i'm looking at.

 

To get a accurate reading use a manometer,( guage that measures crankcase preasure ) or how much oil are you going through ? That might be an other way if it is not leaking

 

Guess I wouldn't know how much oil someone was going through but if I was suspicious I could put the gauge on it.