I give up.

 

I'm a lot slower than most......try explaining it one more time......only slower.

 

I would think there could be variables there. I could see a 40* spread in cold ambient temps, running the heater, little to no flow thru the rad. I wouldn't think the spread would be that much in 3 digit ambient, running a/c and the stat is wide open allowing constant high flow thru the rad.

 

This is my thinking.

The setting:

Dash reads 208* (from sending unit at the back of the head)

IR temp on thermostat housing reads 208*

IR temp on lower rad hose (where my fan switch should be, where it's COOLER) reads 176*.

If I put my fan switch up on the thermostat housing (208*) the fan would kick on at 176* not allowing it to be at the correct temp.

UNLESS. I had a later model switch.

???

 

In the name of science, please try putting the fan switch on the thermostat housing and report the results.

Disregard any info given through testing which reveals that the temp at the back of the head is about 208*, that the CTS is at 208*, and that the fan kicked on at 208*.

 

I would have to rewire it to run up there, also forcing me to get a later model switch as well.... the rad style is out of the question because it won't fit in the t stat housing...

 

Therefore making this myth plausible. But not confirmed.

 

What you are failing to see is that the engine's cooling system holds about 2 gallons.

The water pump probably moves 5 gallons PER MINUTE at cruise.

Not to much time for temps to vary alot.

 

If I'm under standing it correct, the early model rad mounted sensor triggers @ 208* (not 176*). If the early model sensor is mounted/relocated to the stat cover, it's more likely to see 208* coolant temp there, than when mounted in the cold side of the rad (it's normal mounting location).

If that's the case, then the early model sensor mounted in the stat cover will turn the efan on sooner and run it longer than the late model sensor that triggers @ 218* and is normally mounted in the stat cover. Right?


Again, it depends on ambient temps/driving conditions. Agreed, at hi-way speeds coolant flow is rapid but there may be little to no flow thru the rad at hi-way speeds due to the stat being closed. If the stat is closed, coolant flow is really, really, really rapid thru the bypass loop.

 

Let's say 30* Just because I caught it baking hot doesn't mean the sky is the limit.

The IR temp gun seemed accurate for a couple tests I did...Ice was 32*, boiling water about 212. T-stat normally around 195*. So yea, the brass hex housing of the switch, 176*, fan running.

Pretty much no doubt that if HO has a fan switch in the T-stat housing, it's gonna trigger at a higher temp. IN your shoes JamDeaper, I'd hit the JY, grab a housing with that switch in it, wire it up and don't look back!

 

I may give her a whirl. If not. I'm sticking with my in cab switch.

 

R we saying there r 2 different temp "in the rad" sensors?......176* and 208*?

 

No. Lower rad temp 176* and thermostat housing temp 208*

 

So there's 2 different "in the stat cover" sensors?......a 208* and 218*?

 

No.