What Causes Engine Breather Pipe to Spray Engine Oil?

2 Answers
DanielaMarie
07/25/25 6:03am
There are several main reasons why an engine breather pipe sprays engine oil: 1. Issues with the crankcase ventilation system: The simplest troubleshooting method is to directly pull out the oil dipstick to check if oil is spraying from the dipstick insertion tube. If so, it indicates a damaged PCV valve. 2. If the vehicle's breather pipe is connected to the upper section, consider potential problems with the valve stem seals: Generally, oil discharge through the breather pipe is due to excessive crankcase pressure. If the engine was recently serviced, residual oil in the cylinders may cause temporary oil discharge. However, if oil leakage persists after prolonged operation post-repair, it may indicate worn turbocharger floating bearing seals causing the leakage.
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StAriana
08/10/25 6:01pm
I've driven many old cars and have encountered the issue of the crankcase breather tube spraying oil. Once, my old car sprayed oil on the highway, leaving oil stains all over the road—it was really frustrating. Usually, it's because the PCV valve is broken or clogged, which is a critical component of the crankcase ventilation system. When the pressure inside the engine gets too high, the oil gets forced out. It could also be due to overfilled oil or worn piston rings causing poor sealing, allowing oil to mix with the exhaust gases. If the oil spraying continues, not only will the car emit blue smoke, but the internal engine wear will accelerate, leading to more expensive repairs. I recommend not ignoring it and taking the car to a repair shop immediately to check the PCV system to avoid costly overhauls.
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