I've done a search but haven't had much luck with it helping with my cooling/over-heating issues on my 97 Formula
The car runs fine but lately it will constantly runs with the temp gauge past the second tick mark. It does this regardless if I'm crusing on the highway during a cold night or around town. Now here is what I know is good:
- System is Bleed & Filled Properly (at least I believe the ratio of coolant/water is correct)
- Water Pump has about 45k miles
- Thermostat in Water Pump I believe is original
- Temp Sensor in water pump is 15k miles
- Radiator is clean and air-dam is in place
- Fans/Relays all work
- Coolant is drained-replaced about once a year but never done a full back-flush on entire system (except the heater core).

Therefore I'm a bit at a loss since it used to always run around ~190 and just past the first mark on the temp gauge and over the past 3 months this issue developed.
I'd appreciate any thoughts or input. Thanks.

 

It would be easy to swap in a new thermostat or test the one you have.

 

Would a bad radiator cap also cause these symptoms? Nothing is boiling over or being pushed out though.

I assume when a thermostat is bad or starts dieing is will do so in the closed position and thus prevent flow to the radiator causing over-heating issues.

If I test the thermostat is there a measurement or way of telling if its fully or partially opening? Thanks.

 

You can look at the thermostat and tell if it is open when you have it in a pan of water on the stove.
http://shbox.com/1/tstat.jpg

 

If I'm not mistaken if your t-stat is stuck closed you'll overheat whereas if it were to be stuck open would yield a much more consistent coolant temperature regardless of outside temperatures and driving conditions.

 

Are the fans coming on? Maybe one or both of them are burnt out?

 

Well both fans do come on, the car just runs warmer than typical. I was going to replace the thermostat, since I assume those tend to slowly die over the years, but when I started inspecting the housing I noticed there was a lot of what appeared to be either silicone or some gasket material that the auto shop may have used when I had my water pump done years back.

Is it possible they filled the area with sealant, or could that just be the black gasket from the thermostat "oozing" out after so many years?

I'm reluctant to take it all apart and then not be able to seal it up again with a new thermostat. Also, what is the torque on the thermostat bolts, I've seen everything from 20 ft-lbs to 87 in-lbs? Thanks all!

 

89 lb. in. is the torque value for thermostat bolts and there is no gasket to be used, other than the rubber o-ring that is on the thermostat, itself.