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Old 07-25-2002, 02:44 AM
stephenson stephenson is offline
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Join Date: Dec 2000
Location: Fairfax County, Virginia
Posts: 856
Way to Go!

I have been thinking about overheating (since mine did) for awhile and it comes down to some simple stuff that gets all mixed up ... the logic trail is pretty clear.

Try this on:

If the engine overheats while running at 50 mph in normal temps with air conditioning off, it probably isn't:
- viscous fan
- electric fan
- maybe not even a pressure leak

It may be:
- tstat
- radiator
- maybe a pressure leak

I have yet to read of someone with a bad waterpump that affected cooling - they may blow a seal or bearing, but I am not sure how they would pump less unless vanes were worn down (hard to imagine) or the housing or inlet/outlet were clogged.

If overheats at idle, it could be:
- viscous fan
- electric fan
- pressure leak
- tstat
- radiator

OK, so what is easiest thing to do?
- replace tstat
- check for pressure leak at cap (most likely)
- see if electric fan is running (pretty easy)
- check to see if viscous or mag fan clutch is locking up (easy)
- last thing - replace radiator (it is the most expensive)

I am finally beginning to think right about this overheating thing ... although, I could be wrong.
George Stephenson
1991 350 SDL (200K and she ain't bent, yet)
former 2002 E320 4Matic Wagon - good car
former 1985 300 CD - great car
former 1981 300 TD - good car
former 1972 280 SEL - not so good car
a couple of those diesel Rabbits ...40-45 mpg
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