Hello everyone! I am the very proud owner of a 1977 450SEL with the 4.5L V8. The car is in great shape (three identified areas of small rust) and has been undercoated at one time. Car currently has just shy of 40,000 miles. My question is this.

Concerning engine coolant temp. When I first start the car the needle is buried (pointing right at 6 o'clock position) and as I drive is slowly comes up, so I feel it is working. However, it only gets up to between 175 and the tick mark immediately below 175 (150F???). I don't think that is warm enough. The vents will blow hot air so the heater core is getting coolant. My concern is that I live in NJ, need to get the car inspected and am worried about emissions. Also, winters here are cold and I need the heater to work when it is real cold out.

Ideas? Thermostat stuck open?