blowby is through rings..

But, the guides on early M103's were soft- they wear and age/head and loose guides cause failure of the valve stem seals. The vacuum on the intake stroke, pulls the oil through the guide and down into combustion.

M103's are not real leakers- mine's dry and it's had 1-2 v/c gaskets, re-seal the timing cover 2X, and the big o-ring on the oil level sensor once. 25 years of driving.



Michael