I have a 1999 C230K with 200,000 km (120,000 miles). It has the 2.3 litre supercharged 4 cylinder M111 engine. Runs well with great fuel economy.

This winter, in recent cold temperatures (-5 C or about 23-25 F) the car does not warm up to full operating temp of 90C - more like 70C to 80C. The air from the heater is warm enough but not really hot. When the car is idling the heater air cools noticeably and then warms as revs increase.

Is this normal? This doesn't happen with our other vehicles so I don't know if this is normal for this model or the pump/thermostat needs attention.

Also, the car has a difficult time keeping the side windows clear of condensation. I don't see any fluid loss at the water pump or loss in the amount of coolant.

Are these signs of a worn water pump or faulty thermostat? Anything else I should check?

Thanks,

Paul

__________________
1989 300E
1999 C230 Kompressor
2005 Toyota Highlander AWD

Also owned:
1964 Chevrolet Impala (first car)
1972 Fiat 124 Sport Spider (first sports car)
1976 VW Scirocco (first new car)
1970 Pontiac Parisienne (epitome of bland)
1980 VW Scirocco (last new car)
1953 GMC 6x6 (amazingly well engineered)
1967 Austin Healey 3000
1987 F150 4x4
1978 F150
1987 VW Jetta
1992 Toyota Previa AWD
2003 Toyota Sienna
2001 Nissan Pathfinder 4WD
1949 John Deere Model M