I have read some information on the web that having a bad PCV Valve can cause a rough idle but what else can happen with one? I just wanted to know so I and others will know what needs to be done if any thing. I have a metal PCV Valve which I guess supposedly does not need to be replaced. Tomorrow I plan on taking it off and cleaning it out and then testing it. I just wanted to see what other problems can be caused by one that needs to be replaced. This would help me in knowing what other problems I have that may be just this.
Your PCV is the vent in your engine that takes harmful vapors and lets them get burned in the combustion process. It is a cheap item relative to replacing seals because too much pressure will cause leaks. I would also recommend that anyone reading this Google something to the affect of ( What Problems Can Occur With a Clogged PCV). I hope this helps everyone.
Talking from experience, a faulty PCV valve can cause major problems. I had a bad problem with my engine shuddering, and loads of intermittent blue smoke out the tail pipe. This was alongside other problems, such as poor fuel economy, poor acceleration and no power. I replaced everything imaginable that would cause these symptoms to no avail. Dealer said my engine is toast, and told me I need a complete rebuild at a cost of $2,100.
My PCV valve is located at a very inconvenient location, and the intake manifold must be removed to access it. Once the manifold is out, it's a minute's job...but its the 1 hour job to remove the intake manifold that I hate. That said, I got off my lazy backside and replaced it. The shuddering disappeared, there's no more smoke out the tail pipe and power is restored. Part only cost me $15 for an OEM, but it did the engine loads of good.
I used to think that a PCV valve was just a check valve.....to prevent any backfire into the intake from getting on down into the crankcase. While the PCV valve is a check valve, it provides a much more important function. There is a spring in the valve.....and as the vaccum in the intake manifold varies, the pressure on the spring varies......
The loose "rattle" part of the valve presses more against the spring at higher vaccum, making the opening where it seats smaller......the air is flowing through the opening faster with the higher vaccum, so the opening is smaller to limit the flow.
Under high accelleration........when you have a low vaccum in the intake manifold, the spring presses the loose part away from the seat.....making the opening bigger.....as air flows slower at the lower vaccum, the larger opening permits more air to get through.
So....in short, the PCV valve serves to meter the air flow from the crankcase into the cylinders.......keeping a consistant flow.......not too much....but still enough to get all the harmful vapors out of the crankcase.
The spring can loose tension......and/or the valve seat can wear......both things that you cannot tell by shaking the PCV valve and listening to the rattle. These 2 things will cause the valve to not correctly meter the flow of harmful vapors out of the crankcase.
Too much flow will draw excessive oil into the cylinders.....commonly causing carbon buildup inside the cylinders....which leads to pinging.
Too little flow does not get enough harmful vapors out of the crankcase.....which leads to sludge issues.....oil breakdown....and excessive engine wear.
Going the extra mile to make sure to replace the PCV valve when needed.....with the correct high quality part is important to keeping the engine running in tip top shape for a long time.
