Clearing Up PCV Valve Problems
by Pat Goss
One of the most overlooked systems on the car is the PCV system, Positive Crankcase Ventilation. And most people make some serious mistakes because they think the PCV valve, such as I have here in my hand a couple of different styles, the PCV valve is all there is. And they replace that periodically and think they’re good. Well, that’s wrong. There’s a lot more to a PCV system than just the valve.
What the PCV system does is it draws fumes from the oil pan back into the intake manifold and burns them to reduce emissions and to protect the inside of the engine. That means that we have to have a vacuum source that sucks the fumes out of the valve cover into the intake manifold.
A second hose is connected down to the crankcase, and the fumes are pulled out of the crankcase through the valve cover into the intake manifold. But we also have to replace anything that we take out of there, so we have a hose that allows fresh air to replace the fumes that we’re sucking out of the oil pan. That means that there’s a whole bunch of different things, hoses and clamps and so on, that comprise the PCV system.
Here we have some hoses that just literally just fell apart, and it did serious damage to the engine. Actually it caused some seals to be blown out of the engine because of too much pressure that couldn’t be relieved through the PCV system. So you check all of the hoses and you may find you need new hoses. You go to the parts store, and what do they say? We don’t have PCV hose but you can use fuel hose. It’s about the same thing. Or they say you can use vacuum hose. The vacuum hose won’t stand up to the oil that comes through this system. The fuel hose is designed for internal pressure. It will collapse under the vacuum of the PCV system. PCV hose is designed specifically so it won’t collapse. So insist on PCV hose, never fuel hose or vacuum hose.
Now what’s going to happen aside from seals? Well, it could get a lot worse. Here we have oil that came out of a late model engine that didn’t have that many miles on it, but the PCV system had never been serviced. It clogged up, and the oil turned to this nasty sludge. We see more of it here in the valve cover off of that engine. The engine was destroyed, all from failure to service the PCV system. Check it, all of the parts of it, at least once a year or every 12,000 miles.
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