Pcv.. Small Parts That Can Do Alot Of Damage

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Positive Crankcase Ventilation valves, aka PCV valves. They pull fresh air into the engine?s crankcase and draw fumes out. They?re small, they?re inexpensive but oh can they play havoc with an engine. PCV systems control harmful fumes emitted from hot oil, and combustion gasses from burning fuel. Both are normal. Before PCV these fumes were expelled into the atmosphere and contributed substantially to automotive-based air pollution. Today PCV systems are standard equipment; they remove crankcase pollutants, which are then destroyed through a re-burning process.

It works like this. Engines produce vacuum, which is just like the suction a vacuum cleaner produces at the end of its hose. Vacuum = Suction! Engineers take advantage of engine vacuum to suck fumes out of an engine?s crankcase. Not only does this eliminate pollutants, it maintains a vacuum inside the engine.

The biggest problems with PCV systems are lack of knowledge and poor maintenance. Without routine testing and maintenance, PCV systems quit working which could mean failed emissions (high carbon monoxide and possibly hydrocarbon readings), stalling, lowered fuel mileage, rough idle, hesitation, illuminated ?check engine light,? oil-soaked air filters, and oil leaks.

What about engine crankcase vacuum, how does it affect things? When a PCV system is working right there will always be a vacuum (suction) inside the engine?s crankcase. But, when the PCV system isn?t working, vacuum becomes pressure. That?s a problem because engine seals and gaskets are designed to work under vacuum, therefore when vacuum turns to pressure it can cause oil to be forced past seals. In severe cases, crankcase pressure causes seals and gaskets to literally be pushed out of the engine resulting in an oil hemorrhage.

With stakes so high, why are PCV systems almost universally ignored? Usually lack of knowledge and to add insult to injury, even when a check is performed it?s usually only the PCV valve, not the entire system. A PCV system is composed of a PCV valve, usually a hose to connect the valve to a vacuum source, a second hose for incoming air, and a filter to clean incoming air. All PCV parts must be checked on a regular basis. Always replace your PCV valve and check the rest of the system at least once every year or 12,000 miles.

Somewhere over the eons it became an accepted but erroneous assumption that if a PCV valve rattled when shook, everything was okay. That little tidbit of misinformation can be costly. Checking a PCV system involves much more than just shaking the valve. PCV testing is best left to experts but for a quick and dirty do-it-yourself check, start by disconnecting the hose for incoming air, usually at the air filter housing. With the engine idling there must be sufficient vacuum to firmly hold a business card to the end of the hose. If there isn?t enough vacuum to hold the card in place it?s time to visit a repair shop or the local autoparts store.

PCV --- small parts, obscure parts, parts that can cause hundreds of dollars worth of damage in a matter of minutes if they don?t work properly.



Information from Pat Goss from http://www.patgosscarworld.com/