Coolant Temperature Question

[mark2016]

Noticed driving in winter weather more this week that my 2001 4.0 SOHC is running on the cool side. The needle on the temperature dash gauge never goes much above the low line. Ran my scanner while driving and it never got above 170 degrees even at highway speeds 65-70mph. Upper radiator hose is hot as normal, no other signs of issues. Which could this be, the ECT sender, the ECT sensor, or the Thermostat? No codes have popped up, it was just bothering me.

 

[koda2000]

Replace your thermostat. 192-195 degrees F. Any time a vehicle runs too cold it's always the t-stat.

 

[mark2016]

replace your thermostat. 192-195 degrees F.

Kind of what I was leaning to. Do I need to go Motorcraft or will off the shelf in a parts store do and if so what brands should I look for or avoid?

 

[koda2000]

Kind of what I was leaning to. Do I need to go Motorcraft or will off the shelf in a parts store do and if so what brands should I look for or avoid?

I've used Stant and Motorcraft t-stats with success. Motorcraft's are expensive, but they are OE. The last one I put in was a Motorcraft and it was around $37 at O'Reillys. I'm sure it's even more from Ford.

 

[Flash]

It's the thermostat.

If the engine is running too cool the ECU will richen the fuel mixture to compensate.
This can was the oil off the bores and cause excessive wear.

 

[mark2016]

It's the thermostat. If the engine is running too cool the ECU will richen the fuel mixture to compensate. This can was the oil off the bores and cause excessive wear.

Good point, glad I don't have to drive it again until the Thermostat arrives tomorrow, Amazon had the best price for Motorcraft at $22.

 

[mark2016]

It's the thermostat. If the engine is running too cool the ECU will richen the fuel mixture to compensate. This can was the oil off the bores and cause excessive wear.

Kind of started to see that in my fuel trim data too, long term was approaching 10% where normally it stayed below 6%.

 

[mark2016]

Replacement Motorcraft Thermostat worked like a charm, temps are right on my scanner and dash gauge now in the middle range. Amazing how much better she runs too, felt like my 2013 Fusion in terms of how smooth the engine was and much better takeoff from stops and overall acceleration.