Engine oil leaks should not be ignored. Oil leaks can leave greasy ugly stains on your driveway. But the real danger is potential engine damage or failure if your engine runs low on oil.
Oil leaking at the back of the engine may also cause the clutch to slip if your vehicle has a manual stick shift transmission.
Oil can also produce blue smoke and unpleasant odors if it drips onto a hot exhaust manifold or exhaust pipe.
The first sign of trouble is usually drips or stains under your vehicle after it has been parked overnight. If the color of the liquid is dark brown or yellow, and it feels slippery or greasy, it is probably motor oil. A pink or red slippery liquid would most likely be automatic transmission fluid, while green or orange liquid with a sweet smell would most likely be antifreeze. A clear, oily liquid would probably be power steering fluid.
If you suspect an oil leak, check the oil level on the dipstick (engine off) to see if the oil level is low. If it is low, you probably have an oil leak. If the oil level is okay (between ADD and FULL marks on the dipstick), check the other fluid levels (ATF, coolant and power steering fluid) to see if any of those fluids are low.
WHERE OIL LEAKS OFTEN OCCUR
Engine oil leaks occur most often at the valve cover and oil pan gaskets, timing chain cover and the front and rear crankshaft seals. As an engine ages, heat can cause corkgaskets to harden and shrink. Heat can also cause rubber (neoprene) gaskets and seals to harden and lose elasticity. After six or seven years of service, the engine may start to leak oil. The older the engine, the more likely it is to leak oil due to aging gaskets and seals.
Oil leaks can also occur if the crankcase is overfilled with too much oil, or the Positive Crankcase Ventilation (PCV) system is clogged, allowing pressure to build up inside the engine.
When oil leaks out of an engine, it attracts dirt. So look for greasy stains around or below gasket seams and seals. Sometimes you can see oil dripping out while the engine is idling. But more often than not, the oil just slowly seeps out causing a buildup of grease in the vicinity of the leak.
FIXING OIL LEAKS
Crankcase oil additives can sometimes help slow a leak by causing aged gaskets and seals to swell, but no additive will stop a major leak or repair a broken gasket or worn seal. Sooner or later you will have to replace the leaky gasket or seal.
NOTE: Some motor oils are specially formulated for high mileage (over 75,000 miles) engines. These oils contain extra seal conditioners to help keep gaskets and seals soft and pliable so they don’t leak. Using this type of product in a high mileage engine can reduce the development of oil leaks.
To fix a leaky gasket, remove the cover or component over the gasket and scrape away all the old gasket debris from both mating surfaces. Wipe the surface clean with a rag. Then apply gasket sealer to both sides of the replacement gasket if it is cork (DO NOT use sealer on rubber gaskets), then position and reinstall the gasket on the cover. Then install the cover and tighten the bolts to specifications.
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