Temperature Fluctuation

[BChad956]

Hey Everyone,

when i'm driving my truck the temp gauge seems to move around a lot. it will range anywhere from noticeably below the half way point to slightly above it. this is after the engine is warm and i have been driving for a while. i can tell when the thermostat opens because the truck will get pretty warm shortly after starting (over halfway) then i'll see the gauge drop. after this the temp really seems to fluctuate a lot, more than any other vehicle i have ever owned or driven. does any one else's truck do this?

 

[funkingonutz]

yup mine does the same thing, if i look real close at the temp gauge i can see it go up and down and kinda "shake" had it go over halfway once while on the highway in the rain, other than that it usually goes up to the halfwau point then down to the "normal" range. Fords always run cooler then any other vehicle ive seen, the temp gauge usually stays in the first third of the gauge, and hardly ever moves.
Try backwashing your radiator, bugs, leaves, mud, and road debris like to clog up the fins in the front of the rad. esp. near the bottom...NEVER use a pressure washer!! you will bend the fins.
easiest way to do this is to take the rad. out (super easy)
also might want to do a pressure test to see if the coolant system is leaking, my lower hose leaks right where it connects to the water pump.

 

[funkingonutz]

your thermostat opens when the upper rad. hose is hot, by the way

 

[MAKG]

If you don't have NUMBERS on your temperature gauge, you're trying to read tea leaves with them in the next room while you struggle in a straitjacket. You have NO IDEA what is going on, and trying to diagnose from that might as well involve a dart board.

Get a calibrated, mechanical temperature gauge, and keep in mind that some 10 deg of temperature cycling is completely normal (20 deg or more isn't even worrisome), as the thermostat is largely just open or closed.