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The PCV Valve is a little, inexpensive part that does a big job for St. Louis drivers. PCV stands for Positive Crankcase Ventilation.

The crankcase is the bottom area of the engine that holds the oil. When the sedan engine’s running, fuel is burned to generate power. Most of the exhaust from combustion goes out through the exhaust system. But some exhaust blows by the pistons and goes into the lower engine, or crankcase.

These hot gases are about seventy percent unburned fuel. This can dilute and contaminate the oil, leading to damaging engine oil sludge. It can also cause sedan engine corrosion, something we see occasionally at Master Auto Repair. At high speeds on St. Louis freeways, the pressure can build up to the point that gaskets and seals start to leak.

Back in the old days, engine makers simply installed a hose that vented these gases out into the atmosphere. But starting in the 1964 model year, laws mandated that these gases be recycled back into the air intake system to be mixed with fuel and burned in the sedan's engine.

This is much better for the environment and it saves gas too. (Budget-conscious St. Louis drivers take note!) The little valve that controls all this action is the PCV valve. The PCV valve lets gases out of the engine, but won’t let anything back in. Over time, the vented gases will gum up the PCV valve and it won’t work well. That can lead to all of the problems I’ve already described, oil leaks, excessive oil consumption and wasted gas.

Fortunately, it’s very easy to test the PCV Valve at Master Auto Repair and quick and inexpensive to replace. Even so, it’s often overlooked because many St. Louis drivers don’t know about it. Check your sedan owner’s manual or ask your Master Auto Repair service advisor. If this is the first time you’ve heard of a PCV valve, you might be in line for a replacement.

There’s another aspect to the PCV system. In order for the valve to work correctly, it needs a little clean air to come in. This is done through a breather tube that gets some filtered air from the engine air filter. Now some vehicles have a small separate air filter for the breather tube called the breather element. That’ll need to be replaced at Master Auto Repair when it gets dirty.

Please ask your friendly St. Louis service advisor about your PCV valve. For the price of a couple of burger combo meals in St. Louis, you can avoid some very expensive deep engine repairs.