what causes blow-by?
 

yeah ive been hereing about that lately and i just dont get it.......i know newb question ;D

Re:what causes blow-by?
 

excessive pressure in the crank case i believe.......

Re:what causes blow-by?
 

oil blow by? Usually tears in the piston rings... oil gets up and burns into the cylinder. Other things can cause oil to get in there as well, like teg mentioned, or possibly something wrong with a valve and oil leaking from there.

Re:what causes blow-by?
 

bad rings.

Re:what causes blow-by?
 

Like they said bad rings or too much crankcase pressure, which could be cause from a bad pcv or pumping boost into the crank case

Re:what causes blow-by?
 

Is this the reason for catch cans?or is it for a whole different purpose.

Re:what causes blow-by?
 

I have bad rings in my A6 :(...cilinder 2+3...burns oil. Time for an engine swap and build the A6 ;D

Re:what causes blow-by?
 

too much crank case pressure, bad PCV crank case venting goes wrong, not changing oil as frequent as you should, will cause rings and cylinder walls to be damaged....

thus causing blow by.