PCV valve needs regular checking
If it plugs, hydraulic havoc can mean very expensive repairs
With the cold weather here for a while, a very small part can play havoc with most vehicle engines and cause expensive repair bills if ignored during our snowy season.
Positive crankcase ventilation has been around almost as long as internal combustion engines, with very little advancement in design or application.
At the very beginning, automakers soon found out that when air from the combustion process “leaked” past the pistons and entered the crankcase in their newfangled creations, it created positive pressure that caused substantial oil leaks. By simply incorporating vent holes in an upper engine cover the problem was resolved, except the fumes flowing back into the passenger compartment were a cause of much discomfort. To that end, a simple tube leading down to the bottom of the engine compartment was attached to the vent. This system sufficed until the Second World War, when it was discovered that tank engines were ingesting water through this tube when fording rivers and creeks. At this point the humble little positive crankcase ventilation (PCV) valve was invented to cure the problem.
But it wasn’t until the late 1950s that the PCV valve started to appear on automobiles, as raw oil fumes from the old vent tube system were found to be a major cause of smog in dense urban areas. So in reality, the humble PCV valve was the first emission control device.
What can lead to hydraulic havoc on vehicle engines in winter is the effect of extremely cold temperatures combined with short stop and start runs and high humidity. These conditions can cause the PCV valve to freeze shut, leaving the internal pressure nowhere to vent. When this pressure builds to a peak it can cause engine oil seals to fail, followed by massive oil loss, leading to main bearing failures if not caught in time. For some engine designs it can also mean the demise of timing and accessory drive belts when they get covered in oil. In all, it can bring substantial repair costs and it catches vehicle owners by surprise every time it happens.
To keep this from happening on your next chilly commute, have your PCV system checked the next time you take the daily driver in for an oil change. Many engines now use a metal orifice tube with a specifically shaped and sized inner wall that duplicates the function of the old-style PCV valves. Even these should be checked regularly on vehicles over three years old, especially in cold weather. If you do a lot of short runs during the winter (drives of less than 15 kilometres that never get the engine fully warmed up) consider shortening your oil change intervals to keep the moisture content of the oil to a minimum.
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