1. Excessive crankcase pressure: This can be caused by a number of factors, including worn or damaged piston rings, a faulty PCV valve, or a clogged oil filter. When crankcase pressure builds up, it can force oil out of the dipstick tube and PCV valve.
2. Worn or damaged piston rings: Piston rings are responsible for sealing the combustion chamber and preventing oil from seeping into the cylinders. When piston rings are worn or damaged, they can allow oil to leak into the cylinders, which can then cause oil blowback.
3. Faulty PCV valve: The PCV valve is responsible for regulating the flow of gases and fumes from the crankcase to the intake manifold. When the PCV valve is faulty, it can cause excessive crankcase pressure and oil blowback.
4. Clogged oil filter: A clogged oil filter can restrict the flow of oil to the engine, which can cause oil pressure to build up and lead to oil blowback.
5. Incorrect oil level: If the oil level in the engine is too high, it can cause oil blowback. Check the oil level and make sure it is at the correct level.
6. Oil sludge buildup: Oil sludge is a thick, tar-like substance that can build up in the engine over time. Oil sludge can clog oil passages and restrict the flow of oil, which can cause oil blowback.
7. Worn or damaged valve seals: Valve seals help to prevent oil from leaking into the combustion chambers. When valve seals are worn or damaged, they can allow oil to leak into the cylinders, which can then cause oil blowback.
If you are experiencing oil blowback from the dipstick and PCV on your Chevy truck with a 350 engine, it is important to have the issue diagnosed and repaired as soon as possible. Oil blowback can cause engine damage and can also be a fire hazard.
