What Causes Engine Breather Pipe to Spray Oil?
1 Answers
Engine breather pipe spraying oil may be caused by aging of the crankcase ventilation valve, or failures in components such as pistons, cylinder liners, piston pins, and piston rings, which lose their original sealing effect, leading to oil spraying. Additionally, severe wear between the valve stems and valve guides, creating excessive clearance, can also result in oil spraying. If the breather pipe oil spray is caused by issues in the crankcase ventilation system, the simplest troubleshooting method is to directly pull out the oil dipstick to check if oil is spraying out from the dipstick tube. If so, it indicates a damaged PCV valve. During engine operation, high-pressure exhaust gases enter the crankcase, creating significant pressure inside. For crankcase safety, these exhaust gases are recirculated into the engine for combustion via the PCV system. If the PCV valve is damaged, the high-pressure exhaust gases in the crankcase have nowhere to go and can only spray out through the pipes. If the vehicle's breather pipe is connected to the upper section, then valve stem seal issues should be considered. Generally, oil discharge from the breather pipe is due to excessive crankcase pressure. If the vehicle has just undergone maintenance and there is residual oil in the cylinders, short-term oil discharge may occur. If oil leakage persists after prolonged operation post-maintenance, it is likely due to wear in the turbocharger floating bearing seals. Other complex reasons can also cause oil leakage from the exhaust tailpipe. Observing whether there is oil in the intake manifold or exhaust manifold can help identify the leakage location and cause.
