Temperature gauge question

[mustangmann]

I have a 98 sho and this morning while driving to work i noticed that the temp gauge was fluctuating a little bit. I have never seen this happen before. This was the coldest morning so far of the season. Also, my car seems like it takes a long time for it to heat up and the heat is not real warm either. Is this a sign of the thermostat going? I have never replaced it before and the car has 237,000 on it. How hard is it to change the thermostat? Is there directions anywhere on how to change it? Any input appreciated, thanks!

 

[jpSHO]

Sounds like you need a thermostat if the car is not reaching normal operating temp or maybe you have air pockets in the cooling system. I would try bleeding it first.

 

[Silvapain]

The most common cause is low coolant level caused by a cracked coolant reservoir tank. If your reservoir has a black top, just go ahead and replace it. You can buy the revised clear-top Dorman unit from Autozone for under $30.

 

[NebraskaSHO]

Duratec one fits.