Guage goes up to about 200 quickly then back down to about midway. Mechanic says this is normal with a 195 thermostat. Is this true or do I need to replace the thermostat.

 

My 195 Degree thermostat runs about 200-205 all day long when engine is running at full operating temp...

 

i think mine usually runs about 165, and thats with a 195 degreee t-stat.

 

My blazer runs around the 200 - 205 mark as well... It'll drop down fairly quick though, when I stop moving, but that's usually only when it's below -15 degrees F

 

There are a couple of sensors that deal with engine coolant temperature. One sends its signal to the computer and the other to the Instrument Panel temp gauge. To tell if the sensors are not defective you would need a Code Scanner or get the codes scanned at an auto parts store that does this or find a mechanic or dealer that would do this for you...

As for your gauge going quickly to 200 then back down may not be normal but may also not be the thermostat...could be sensor...I just recently replaced my t-stat last spring and it now goes to 200 slowly and stays there until I park for a while...