2017 F150 engine temperature stuck at 120

[Offshore_life]

So I did my annual service including water pump and thermostat. Question normally my motor will slowly warm up when start from 80 degree to 120 at idle. When I check the temperature via Simrad Nmea 2000 it show 120 degree even at cold 1st start up. Even if the key switch is turn on with out staring the motor .

[boscoe99]

Thank you for the report. Interesting.

[rejesterd]

If you're measuring 120F at idle after warmup (and also at key-on with the motor cold), then the device taking that measurement is faulty. Your thermostat won't even start to open until it reaches about 135F, and it should be fully open when it's closer to 160F.

[boscoe99]

If you're measuring 120F at idle after warmup (and also at key-on with the motor cold), then the device taking that measurement is faulty. Your thermostat won't even start to open until it reaches about 135F, and it should be fully open when it's closer to 160F.

How is it known that wiring or the ECU is not the problem? Are you suggesting to simply remove and replace the sensor and that will solve the problem?

[Offshore_life]

Figure it out . If I ran the motor at idle warm up to 120 degrees. It’s takes a few hours for the MFD simrad for temperature to come back down to 80 degrees on MFD . Must be simrad need to update their software.

[pstephens46]

Good Gawd. What is the problem? Running badly?

run it wide open for five minutes. Wha Is the temp then? Should be 220 plus..... good to go.....

[99yam40]

Figure it out . If I ran the motor at idle warm up to 120 degrees. It’s takes a few hours for the MFD simrad for temperature to come back down to 80 degrees on MFD . Must be simrad need to update their software.

I would think it would take a hot motor a long time to come down to 80 when the air temps are in the 90s

[DennisG01]

It sounds like you are expecting the engine to cool down to 80* within minutes after turning it off. As mentioned, that is impossible. It takes time. A "cold start" is many, many hours after turning it off.

How 'bout this... physically FEEL the engine! Now there's a thought! When it reads 120*, does it physically feel that temp? Or heck, you can get crazy and use a thermometer - or even one of those new-fangle-dangled IR gun thingies.

[pstephens46]

Why not run it and then hose flush it using the fitting. That should bring the temp down as quickly as possible.