1992 TA 5.0 TPI 322,000 original miles, daily driven, 180 thermostat w/correct fan switch and chip. Car normally runs right above the 160 mark on the highway no matter what the temp outside.
The other day while driving home from work my heater control valve blew open and my car overheated on the highway. pulled over, towed it home, swapped out the part and filled the radiator back up and car drives fine. The coolant i used was all 50/50, one new bottle and one i had to mix that i had in my garage for years.
Weird issue I'm having now is the car seems to be running about 20 to 30 degrees warmer since the car overheated. It doesn't go above 220 but gets to it very easily when im in stop and go traffic and while im cruising on the highway it runs around 190 constant where before it was around 160-170.

Could overheating cause the gauge to read differently? Could the overheating caused some damage to something? Did i not fill the car up enough with coolant? Does it need to be burped? Could old coolant be bad and not work as well?

 

You could recheck it and add if needed. Maybe the Tstat is not funtioning right after the overheat.
Check it cold, fill it, and add to cold mark on the resivoir tank; you may not gotten it full

GL

-Bob

 

Have you tried turning the heat all the way up so the water can fill through the heater core and eliminate any air pocket that may be there and add more coolant as needed?

 

I just drove it home today and noticed it runs warmer when the AC is on. With the AC off it seems to run like before. Maybe the heater bypass valve is actually working compared to my old one. I did have the heat turned on when I filled up the coolant. The heat gets hot and doesn't act like there is an air pocket in the heater core.

 

Maybe the 2nd fan isn't kicking on

 

i checked, the 2nd fan is coming on