Q: Emitting smoke out tailpipe after spark plug and valve cover replacement, no overheating, after a week spark have black oil deposi

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I have a 2003 Nissan Altima with under 200k, it's my commuter. I just changed the spark plugs and noticed oil in the vavles. There were three broken seals and I replaced the valve cover along with the gasket as they don't come with replacement seals and are made of plastic. After driving for a week I had noticed initial white smoke at the start and after a minute it goes away but occasionally while driving I'll get a slight sputter and smoke come out the tailpipe. So after seeing that I pulled out the spark plugs to inspect them and noticed two of the four were black with deposits and smell like oil. The car does not overheat. It has a new radiator and I have had the thermostat replaced.

My car has 200000 miles.
My car has an automatic transmission.

It’s pretty common for the spark plug tube seals to fail, allowing the tubes to fill with oil. It could be that when you performed the repair, the seals didn’t get installed properly. Other potential causes for your oil-soaked plugs include worn valve guides, worn rings or a faulty positive crankcase ventilation (PCV) system. Any of these issues can result in blue-gray or gray-white smoke being emitted from the tailpipe. I recommend having a professional diagnose and repair your concern. YourMechanic is an excellent option because we come to your home or office.

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