[A26B]

Originally Posted by Chris H

My 1991 ZR1 has 75000 miles on it. It gets very hot in traffic (around 200) I know the original thermostat is 180. Im thinking I may need to change it. Has anyone else had this problem and have and suggestions on what type of thermo i should get. Also if i do need to change the thermostat can someone please give me detailed instructions on how to do so. (i hate to admit it but im an amateur mechanic and i dont want to screw anything up) Im about to take the car to floida and DO NOT want to ruin it in that heat

You are correct, the original t-stat is 180F. However, that is where it begins to open. It operates fully open in the 105~200F range. 200F is NOT "very hot". In fact, I would say you are doing better than most if you are only showing 200F in traffic on a warm day. 225~230F is more common. Turn the AC off when you are in slow, stop & go traffic if it gets to that range.

I don't think anything is wrong with your t-stat. Virtually all cooling problems are due to accumulation of debris in the front of the radiator. You can't see all of it and it can't be cleaned properly in the car. Radiators needs to be removed for proper cleaning and even then it's a PITA to get all the little crap out of the core.

Low temp t-stats won't make an engine run cooler unless ambient conditions, air flow and radiator heat transfer capability allows.

You can check the cooling fan operation by letting the engine idle until the temp reaches 225F. Fans should come on. A manual fan switch or reprogramming the prom, as others have suggested is a good idea.