Got a gas-guzzler on your hands? Here are
a few general reasons why engines burn oil:
Bad Valve Seats
Valves are located above the combustion
chamber in the cylinder head. The valve-train is lubricated
by pumping oil at 50 – 80 psi of pressure into the top of
the head. Seals are placed at the top of the valves to stop
the flow of oil down into the engine when the valve is open.
When the seals fail, more oil than is necessary will flow
down into the combustion chamber and burned.
Worn Valve
Guides
Valves are guided by small cylindrical
chambers called valve guides. Regular wear and tear causes
slop in the guides, and the excess gap allows the flow of
oil down the valve stem into the combustion chamber to be
burned. In this case, the gap is too great for the valve
seal to stop the oil flow.
Blow-by from
Worn Piston Rings
Pistons in the car engine have seals
around them in the form of rings to serve two purposes:
- Seal the combustion chamber so that the power
developed from the firing of the cylinder is not lost.
- Provide vital lubrication to the cylinder walls.
When the rings wear out, pressure from
the combustion reverses down into the oil pan, pressurizing
it, and forcing oil into the valve covers, through the
breather system, back into the fuel delivery system, and
into the engine to be burned.
Prevention
Keeping oil filter and air filter changed
regularly will keep sludge and carbon build-up down to a
minimum. While you can’t stop mechanical wear, proper care
and maintenance will slow it down, saving you thousands of
ringgit in fuel consumption.