Truck Smokes When Starting and When Accelerating


Since I got my truck a few months ago, it has been smoking. It would put out smoke the worst when I started it. It would also smoke some when I would idle for a while then hit the gas. Everything I read pointed to bad valve seals or piston rings, so I assumed I would have to replace those soon - hoping it was valve seals as that is easier. While going through some regular, higher mileage maintenance I saw that I should inspect my PCV valve. It turns out that the valve was horribly dirty and the PCV valve inlet into the throttle body was completely clogged with oil gunk. You can see the gunk that I scraped out in the picture below.

Here is the old PCV valve. It was servicable, which you can test by shaking it and making sure it rattles, but it also likely had over 100,000 miles on it so I replaced it.

Once I cleaned out the PCV port on the throttle body and replaced the PCV valve, the truck stopped smoking completely. This is because the PCV, which stands for positive crankcase ventilation, keeps pressure from building up too high in the crankcase, as well as sending blowby gasses to the throttle body to be burnt up in the combustion cycle. The pressure was building up in my engine and forcing oil into the combustion chamber, past the piston rings I'm assuming. So I will probably need new rings sooner rather than later but my truck does not smoke now, which makes for a happier time all around.

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