5.0 thermostat. Is there a Quicker unit available?

[Turdle]

Observed issue. According to scangauge, Coolant temp climbs to at least 202 from cold start. Once 202, sometimes as high as 206 is achieved, temp falls to 181, then climbs back to 200, them 181, then around 198, then down to 186, and so on.

It never truly settles in until cruising at highway speed, then not quite settled 197 down to 191

Brings up several things to consider.

The ECT is quite a distance from the thermostat.

The flow across ECT varies, depending on whether heater core valve is open, or closed. The small coolant lines to upper intake from crossover tube allow some flow, just not as much as full heat.

Scangauge data is what the ECT sees. Thermostat sees entirely different coolant.

Maybe I'm overthinking, but this is my observation after 3 different motorcraft dealer purchased thermostats. 3 different radiators, 3 water pumps, 2 engines, and several multi thousand mile mountain trips.

It just bugs me. I want my expensive 193 degree thermostat to show me 193 degrees. Is that asking too much?

 

[410Fortune]

How many miles on fan and clutch?
What’s wrong with 202? 206? The pcm needs to see this temp

Coolant Temps Fluctuate on every digital temp gauge I have ever seen on any machine I have tested

 

[Turdle]

Oh yeah, metal fan 2 different clutches. Motorcraft

 

[Turdle]

And I'm just overthinking this?

 

[410Fortune]

Well yes
The system is working as they intended!
Only reason you see these big fluctuations is because digital readout
You want a more precise reading for the ect correct? That is what you are after? We could re locate it to the thermostat housing old mustang housings or f150 housings had the sensor right there and it will fit your intake or just machine you thermo housing for a sensor there is a flat spot
Not sure how Much it would help? But maybe

Have you tried a stant superstat?

 

[Turdle]

Well yes
The system is working as they intended!
Only reason you see these big fluctuations is because digital readout
You want a more precise reading for the ect correct? That is what you are after? We could re locate it to the thermostat housing old mustang housings or f150 housings had the sensor right there and it will fit your intake or just machine you thermo housing for a sensor there is a flat spot
Not sure how Much it would help? But maybe

Have you tried a stant superstat?

Yes. It locked open during a heat soak , engine off while hot engine cycle. Don't like

 

[410Fortune]

Motorcraft is always a safe bet!!!!