exhaust pressurizing cooling system??????

[JanDebL at aol.com]

Exhaust leaks into coolant system aren't very common on Audis but they are 
common on some of the medium sized diesel engines.  The VT 700 hp Cummins     
V- 12 comes to mind.  We used to find cracked heads which allowed the 
cylinder gasses to escape into the coolant jackets after the engine warmed up 
and the cracks expanded.  If you didn't replace the head before the cracks 
got bigger, eventually the coolant would leak into the cylinder when the 
engine was shut off.  The when you tried to start the engine, you would 
either blow a head gasket, break the ring lands on the piston or bend the 
connecting rods.  Larger diesel engines usually have petcocks for each 
cylinder you can open so this won't happen.
Jan Lahtonen