1. Worn Piston Rings: Worn or damaged piston rings can cause blow-by, which is the leakage of combustion gases past the piston rings into the crankcase. This can result in a loss of compression and power, as well as oil contamination in the spark plug boot.
2. Valve Seal Issues: Worn or damaged valve seals can allow oil to leak into the combustion chamber, which can cause oil fouling of the spark plugs and a loss of power.
3. Oil Overfill: Overfilling the engine with oil can cause the oil level to rise and come into contact with the spark plug boots, resulting in oil contamination.
4. Damaged Spark Plug Boot: A damaged or cracked spark plug boot can allow oil to seep into the spark plug well, causing misfires and a loss of power.
To address these issues, it is recommended to:
1. Check Piston Rings: If the engine has excessive blow-by, the piston rings may need to be replaced. This is a major engine repair that requires disassembly of the engine.
2. Replace Valve Seals: Worn valve seals should be replaced to prevent oil from leaking into the combustion chamber. This is a less involved repair compared to replacing piston rings.
3. Correct Oil Level: Ensure that the engine oil level is correct, as per the manufacturer's specifications.
4. Replace Spark Plug Boot: If the spark plug boot is damaged, it should be replaced to prevent further oil contamination and misfires.
It's important to have the root cause of the problem diagnosed and addressed by a qualified mechanic to prevent further damage and ensure optimal engine performance.
