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Technical
Service Bulletin 89-1R2
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Coolant Leaks into Engine Oil
Any internal leakage of coolant into the lubricating oil in an engine can cause serious damage to the engine. Some examples of areas where coolant could enter the oil are:
- Damaged head gasket
- Cracked head
- Cracked block
- Leaking oil cooler
- Leaking cylinder inner seals
- Leaking injector seals
Coolant causes the lube oil to change chemically as indicated by the milky appearance of the oil. Coolant contaminated oil does not provide the high lubricity required between close tolerance parts, thus causing friction heat. The heat causes more oil deterioration. Sludge begins to form, interfering with:
- Positive operation
of lubrication system pressure regulator valves and the oil by-pass
valve.
- Oil filtration
suffers as filter material becomes plugged. The filter may even
experience such
high pressure differential that interior parts may collapse.
This contaminated
lube oil does not properly lubricate bearings. The first effect is excessive
wear to internal engine parts. The oil does not provide the film strength
needed between the rod and main bearings and the crankcase journals. High
temperature friction melts and welds the bearing surfaces to the journals.
Check the coolant level regularly. Also, check the coolant recovery tank
level. With a cold engine, the fluid level should be at the "COLD
LEVEL" mark. If additional fluid is repeatedly needed to maintain
the proper coolant level, then a coolant leak is likely. It must be determined
whether this is an internal leak or an external leak. Corrective action
should be taken immediately, especially if there is an internal leak.
For additional information, contact:
Filter Manufacturers
Council
P.O. Box 13966
Research Triangle Park, NC 27709-3966
Phone: 919/406-8817 Fax: 919/406-1306
www.filtercouncil.org
Administered by Motor & Equipment
Manufacturers Association
Revised October 2005
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