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

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.

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.

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.