Niagara Gazette — • Pressurized crankcase due to clogged PCV or breather system: Your car’s engine is a giant pump, therefore it must breathe. The PCV (Positive Crankcase Ventilation) system does just this; it allows the engine to exhaust the excess crankcase pressure that builds up (a natural phenomenon of the internal combustion engine). These gases are captured and fed back into the engine to be burned. Carbon (a by-product of engines) can build up in the PCV system, clogging the breathing passages. This, in turn, pressurizes the oil pan and pushes oil up into the fuel delivery system, where it is fed into the engine and burned.
• Blow-by from worn piston rings: The pistons in your car’s engine have seals around them in the form of rings. These rings have two functions: (1) They seal the combustion chamber so that the precious power produced from the firing of the cylinder is not lost. (2) They provide vital lubrication to the cylinder walls. When the rings wear out the pressure from combustion reverses down into the oil pan. Pressure in the oil pan forces oil into the valve covers, then through the breather system, then back into the fuel delivery system, and into the engine to be burned.
TRACKING DOWN THE CAUSE OF OIL CONSUMPTION
• PCV system: Remove the PCV valve with the engine running. There should be a strong vacuum pulling on the valve. If there is no vacuum, the system is clogged with sludge and carbon. It should be cleaned and the valve replaced.
• Valve stem seals and guides: Remove the valve cover and shine a strong light on each valve stem. If the seals are gone, then further inspection is warranted. Pressurize the cylinder and remove the valve spring to closely inspect for a worn valve guides.
• In-depth testing: If nothing is found after checking for a clogged PCV system and valve stem seals & guides, then run a cylinder leak-down test followed by a compression test. These two tests will determine where the wayward oil is going.