What is the phenomenon of engine blow-by?
2 Answers
Engine blow-by phenomenon can be divided into two types: one is caused by piston ring blow-by, and the other is blow-by between the cylinder gasket, cylinder block, and cylinder head. Common locations for engine blow-by include blow-by at the valve cover and blow-by with white smoke emission at the crankcase oil filler port. When encountering engine blow-by, first use a cylinder pressure gauge to check the pressure in each cylinder one by one. The pressure difference between cylinders should not exceed ten percent of their average value. When cylinder pressure decreases, to determine the cause of the decrease, a small amount of fresh engine oil can be injected into the cylinder through the spark plug hole, and the pressure can be measured again. Additionally, methods such as checking the intake manifold vacuum can be used to diagnose engine leakage faults.
Engine blow-by phenomenon, simply put, is when high-pressure gas from the combustion chamber improperly escapes and leaks into the crankcase. This usually happens when the piston rings are worn or damaged while I'm driving, leading to poor sealing. The symptoms are quite obvious. For example, I noticed faster oil consumption, a significant drop in oil level when checking the dipstick, sometimes gas spraying out under the engine cover, blue smoke from the exhaust pipe, and the car struggling to accelerate with poor power. That time, my old car had these issues—fuel consumption went up, and the engine vibrated noticeably. It was only fixed after spending money to replace the piston rings. For prevention, regular oil changes and checking compression pressure are crucial. Early intervention can prevent oil burning or engine overheating problems.
