did you ever consider the fact that the thermostat might be bad? I haven't read the entire thread just wondering

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1990 190E 3.0L

four different sizes thermostats 90c.80c,76cand 60c for racing.I choose 76c as I need a heater.At Autozone I try and ordder stuff here but things I need fast I use local parts stores,being that m104s are hard on head gaskets this is why also lowered themo.

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1999 w140, quit voting to old, and to old to fight, a god damned veteran

I'm just use to seen the temp at the same spot for 12yrs 85C-90C this has been my daily car. I only replaced it was recomended with new WP. Put new belt in old was still the original. Not a drop of oil on engine 177k mi
The WP is the only part I have replaced on the engine well except the biodegradable wiring harness,spark plugs. I service it myself as per owners manual.


Thanks to all for the input.

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1995 E320
1998 E320
1999 E320 4Matic
2000 E320 4Matic
2000 ML320
2007 C230 Sport
2003 Cadillac CTS

So my father-in-laws 300CE was doing the same thing after water pump and thermostat and in a California summer it would hit 120 at a stop light easy.

I just replaced the radiator and it wont go past 82-84 now at all.

I got a NISSEN replacement for around $200 from Rock Auto and its running awesome now.