1986 MERCEDES BENZ ENGINE OVERHEATING... OR NOT

  • Tiny
  • ccocgy
  • 1986 Mercedes Benz

Engine Cooling problem
1986 Other Mercedes Benz Models 6 cyl Two Wheel Drive Automatic 148000 miles

I have a 1986 MB 300e, good shape overall. I've had an overheating problem for a few months. Every time it's " fixed", temp is normal for a few weeks, but then tends to " overheat" - in quotes because the car doesn't have any overheating symptoms: coolant doesn't boil, but rises only to normal hot position on reservoir, airflow thriough radiator is warm, but not inappropriately hot, engine compartment is not overly hot, no burning of oil or any indication of coolant in oil (no real loss of coolant even over time.) Temp guage is only clue - the aux fan doesn't go into " disaster mode" (high speed), but the fan sensor and fan functions have been tested and work fine.

Up to now, I've replaced all hoses, water pump, radiator, reservoir (original had a leak), and have ordered and will replace fan clutch this week (I think it is not clutching in when it gets " hot", if this is really the case, and I've replaced everything else.) The thermostat was checked and was OK (and in good physical condition.) My mechanic, who is Mercedes certified and appears very capable, is a bit stumped.

What are we missing? Many thanks!

Wednesday, April 30th, 2008 AT 12:15 AM

2 Answers

  • Tiny
  • mhpautos
  • Expert
  • 29,839 posts

Hi there,

i would have the calibration of the temp sender checked, you may be just getting a false reading.

Mark (mhpautos)

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Wednesday, April 30th, 2008 AT 12:20 AM
  • Tiny
  • ccocgy
  • Member

Many thanks for your answer, Mark! I've wondered about this (more and more, actually), but have not found a procedure for this (apprenly pretty rare?) I'll pass this info on to my mechanic and probably research further.

Thanks again!

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Wednesday, April 30th, 2008 AT 1:02 AM

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