1. Worn Piston Rings: Worn or damaged piston rings can cause excessive blow-by, allowing oil to escape past the rings and into the ventilation tube.
2. Cylinder Head Gasket Failure: A faulty or damaged cylinder head gasket can also lead to oil blow-by. When the gasket fails, it can create a path for oil to leak from the combustion chamber into the ventilation tube.
3. Excessive Crankcase Pressure: High crankcase pressure can push oil vapor and droplets into the ventilation tube. This can be caused by a blocked or restricted crankcase breather or a faulty PCV (positive crankcase ventilation) valve.
4. Oil Level Too High: Overfilling the oil can also cause oil blow-by. When the oil level is too high, it can create excessive pressure in the crankcase, leading to oil being pushed into the ventilation tube.
5. Improper Engine Assembly: Incorrect installation of piston rings or other engine components can result in oil blow-by.
6. Excessive Engine Wear: Extensive engine wear, such as worn piston rings, cylinder walls, or bearings, can contribute to oil blow-by.
7. Stuck Piston Rings: Piston rings that become stuck or immobile due to carbon deposits or other issues can cause oil blow-by.
To address oil blow-by on your 1973 Harley FXE, it's recommended to inspect and replace worn or damaged components, such as piston rings, cylinder head gaskets, or crankcase breathers. Additionally, maintaining the correct oil level and ensuring proper engine assembly are crucial for preventing excessive oil blow-by.
