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Old 11-11-2000, 02:01 PM
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unkl300d unkl300d is offline
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Join Date: Jul 1999
Location: San Francisco, Ca
Posts: 2,204
Abstract: '95 C280 32K miles. Runs at
normal 80-85 C , but swings up to 95C-98C.
All new coolant and fan fuses (both levels)
are good.

Content: This is a new behavior since coolant change (30K mile service). It would get hot to 98C after about 15-20 minutes of driving.
This was not ambient temp. dependent. Maybe
speed dependant.
I finally removed coolant from upper tank twice and refilled with straight water
to dilute coolant mix. Also
ran engine a while with cap off to burp
possible air pockets.
Seems to have coincidentally
changed behavior. Now it runs
longer time at 80-85C but as a
coincidence, when I go up the (not severe)
hills to my home it climbs to
95-98C. Ambient cool 55-65F.Albeit slower speed of 6MPH.
Freeway it stays at 78-80C.
Ionman posted a similar problem
in late OCT. My passenger side fender
also gets VERY hot, probably because the
exhaust manifold is on that side
and the hot air escapes up to
that side.
This may sound like normal operating temp.
because it is not 'overheating' but it is a new behavior and not satisfactory
to ignore.
I plan a hydrocarbon 'sniffer' test for
coolant later and maybe more antifreeze
Coolant does not have bubbles or oil
while idling with cap off, i.e. no apparent
head gasket leak, so far. Questions: How long do you have to run engine
with cap off to really 'BURP' it?

Any opinions on possible causes or
similar experiences?

Very well maintained C280, never overheated
or abused.

1979 300D
133K miles
1989 300SE
1995 C280

[This message has been edited by unkl300d (edited 11-12-2000).]
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