Irradic Temperature Guage

[doublethrow]

I was not planning to do the work myself. Does the temp sensor feed the thermostat in that it measures the temperature and tells the thermostat to open and close?

 

[doublethrow]

Drive belts look good. Maybe they need to be re-tensioned?

 

[ManUpOrShutUp]

Drive belts look good. Maybe they need to be re-tensioned?

Automatic belt tensioner. It wouldn't hurt to check the tensioner itself though. Mine exploded.

 

[doublethrow]

Seems to happen mostly when AC is running. Could the AC be requiring more torque than normal?

 

[tommyddsr]

If the AC was dragging you'd that bad you would hear your belt squeal. It wouldn't cause the engine to overheat on it's own. Definitely check the temp sensor as it controls the fan as well as providing your temp readings.

 

[doublethrow]

Very helpful gents. Thank you. Which of these is the correct temp sensor and can I replace it/them without major work?

Duralast Coolant Temperature Sensor SU8781
Part # SU8781
SKU # 631220
Notes: Coolant temp sensor

Duralast Coolant Temperature Sensor SU8756
Part # SU8756
SKU # 631221
Notes: Cyl head temp sensor

Santech Coolant Temperature Sensor CT0185
Part #CT0185
SKU #101898
Notes: Engine Cylinder Head Temperature Sensor

 

[07navi]

Are you sure it is actually running hot now? I'm surprised it never went into limp mode.

 

[doublethrow]

The dash gauge will hit H which causes the AC to turn off. But I don't feel any cylinders turning off and entering limp mode. It only stays on H for a few seconds before returning to the nominal temperature. The engine fan is running hard occasionally but not always.

Where would I measure the temp inside the engine to independently confirm whether it is actually hot?

 

[doublethrow]

I measured the engine temp at various places. Registers 159-180. Coming out of the radiator it is ~100. Going into the radiator is ~180.

I am confident that this is primarily happening under speed (70mph). But even accelerating to 50mph shows the gauge move.

 

[07navi]

They probably put a Motorcraft thermostat in it but if not there is a chance your stat isn't working right. These modular engines have a double water passage system above and below the stat. The stat needs to shut off the bottom passage when the top part is open, making it critical that you have the proper stat in it. Some aftermarket stats don't even have the bottom plunger/shutoff part and others don't properly shut the bottom passage off. You can be sure with the Motorcraft ones.

But...... if it's not going into limp mode on extended highway speed trips I doubt if it is running hot, regardless of what the gauge says. The sending unit for the gauge is under the intake manifold and tricky to get to if you want to try changing that.