My father in law has a E220 (1995 model). The vehicle used to operate at 80C until the water pump started leaking. Since replacing the pump the temperature peaks at 92C+.Subsequently he replaced the thermostat as well which has made no difference. When driving in traffic the temp fluctuates rapidly. We were told this is normal but I am not convinced, as the previous temperature was much lower than this and stable.We've had the pump rechecked but it seems to be working fine. Please help me establish what the correct specified operating temperature is and why his vehicle ran at a lower temp before replacing the pump?

Thanks from sunny South Africa.....

After replacing the water pump and thermostat - did the system get given a flush and new (MB) coolant???

Any chance of some gunk being displaced and blocking something up???

Cheers

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1988 W126 420 SE

beware of fundamentalists!

did you forget to reconnect the electric cooling fan? Also, possible air pockets are in the cooling system.

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65 190d sold
85 380SE sold
87 560 SL 180K
84 380SE 96K (mint)

could be in backwards.

tom w

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[SIGPIC] Diesel loving autocrossing grandpa Architect. 08 Dodge 3/4 ton with Cummins & six speed; I have had about 35 benzes. I have a 39 Studebaker Coupe Express pickup in which I have had installed a 617 turbo and a five speed manual.[SIGPIC]

..I also have a 427 Cobra replica with an aluminum chassis.

The car is operating as it is designed to do.

This topic comes up a lot. The thermostat starts to open at 87C and is fully open at 102C. Thus, if the car was consistently running right at 80C, then there was previously a problem with the thermostat opening too early. Normal operation would see the car running AT LEAST 85C-90C on the highway and closer to 100C in traffic.

Now if there are wild temp swings for no good reason other than the normal warming up when stopped and cooling down on the highway, then there would be a problem.

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Ali Al-Chalabi

2001 CLK55
1999 Dodge Ram 2500 Cummins Diesel
2002 Harley-Davidson Fatboy
Merlin Extralight w/ Campy Record

If the original poster was writing from Minnesota or somewhere, I would have to contend that it is running a bit hot...but in South Africa this time of year, that's about right..

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2009 ML350 (106K) - Family vehicle
2001 CLK430 Cabriolet (80K) - Wife's car
2005 BMW 645CI (138K) - My daily driver
2016 Mustang (32K) - Daughter's car