I'm kind of a stickler for torque specs. I have no feel for tight.

In my younger day, I used to accidentally break 3/8 bolts tightening them with a regular ratchet.

I just checked the sensor. It reads 12 volts as soon as the key is turned on.

Do they ever fail that way?

Possibly it is showing full voltage but not passing enough amps to run the fan. I've seen that on other vehicles.

If that is true, it should be enough volts to trigger the relay. Only problem is the fan would run all of the time with this sensor.

I have a new sensor and fan en-route but I never know when an emergency will come up and I have to move on to another project. We will be needing the 4 wheeler very soon.

I plan to add a fuse to the toggle they installed and add the relay to run the fan.

That way I can always turn the fan on with the toggle switch if something fails. It's already there so not much to installing an inline fuse for it.

I have the 3 manuals, but could not find torque specs for the 2 bolts I listed

I have a full bolt bin here and quite a few metrics in cans.

I must have incorrectly described the missing bolt/machine screw. It looked like a Phillips head and I was guessing in the #10 / 6 mm range in size. Haven't got to taking it apart far enough to check for sure yet

 

Just look in the general section of any manual. Torque specs are shown for all size bolts that don't have given specs.Plus look at this on batteries. https://www.batterystuff.com/blog/ho...ry-is-bad.html