Infant Failure Of Thermostat

HOTLNC

HOTLNC

Charter Member
Paid Member
After two weeks of beating my head on the wall, I finally found the cause of HOTLNC's overheating problem. A bad OEM thermostat. I got the temperature needle to the M on the scale and felt the radiator. Stone cold.

I pulled the thermostat and replaced it with a defanged 195 degree unit I took out before installing the OEM unit (by defanged I mean I pulled the guts out of it. I'm just using it as a spacer for the O-ring.)

Installing the spacer and O-ring, I filled her up with coolant and did a long test drive. It took until I got to highway speeds before the needle rose above and over the bottom of the normal line. After cruising at 70MPH for a few minutes, the needle finally rested a letter above the cold normal line. This is about where the needle rested with a GOOD thermostat.

I took the OEM thermostat into the house and heated it up. It opened way, way too late -- the water was already boiling.
 
Everything is still running great. I took the car to work today. It was 34 degrees. The temperature needle stayed below the low NORMAL line. There was enough heat for the heater.

If the low temps radically effect my MPG, I'll order another thermostat. Until then, I'm running with the thermostat simulator.
 
After getting two crap t-stats in a row once I have always just put them on the stove in a pan with water and thermometer to check function.
 
I bought a new 180-190 degree thermostat from O'reilly's. The OEM cost 2 times as much and I'm a little down on Motorcraft at this time.

Thermostat: MCS 4048 $9 - 1 penny
Outlet seal: MCS 2390 $1.5 - 1 penny

I'll install it this weekend.

With the thermostat simulator in, it never gets to the normal line when the temperature is below 40!
 
You must log in or register to reply here.
Back
Top