96 Windstar. The engine warms up normally but it goes just a hair past halfway before it drops down to about a third of the way up. It will continue to do this the rest of the driving cycle. It used to just go up halfway and stay there. Is this just because it is winter and normal or is it a sign of a bad thermostat?
It’s a sign of a sticky thermostat.
Thank. It’s going into the 40’s in NY this weekend, so I guess I have something to do.
Sorry. One more question. I looked on Autozone’s website. 195 is the manufacturer’s recommended temperature but this thing always ran a little hotter than I would like in the summer. It has almost 150,000 miles on it. Can I go to 180 or 170?
I wouldn’t, it will upset the PCM. Anyway putting a lower temperature thermostat will not help the least little bit with your overheating problem. 195 is the normal operating temperature, so the 195 thermostat starts to open then and is fully open by 220 degrees. Overheating is well over that, so there is something wrong with the cooling system and it can’t keep up. If the thermostat was fully open at 180 degrees, it wouldn’t matter. (If your cooling system can’t keep the temperature down to 195, then it won’t be able to keep it down to 180 either.)
If you switch to a “cooler” thermostat, your gas mileage will drop slightly, your emissions will increase slightly, your oil will need changing somewhat sooner, and engine wear will be increase. All-in-all, not a good idea.
Ford put the 195 degree thermostat there for a reason, and you should replace the old one with another 195 degree t-stat.
Thank you everybody. Autozone sells a “fail-safe” one for a couple of bucks more, (15.99 vs 9.99). Is it worth the difference?