Not sure if this is major problem yet or not. My temp guage is fluctuating between 1/4 and almost half. sometimes can be running at 70 mph and guage drops to 1/4 then goes back up to 1/2. Coolant was changed 5 months ago and no issues until lately with temps in the 20"s. truck is 2004 4.6 with 60k
has anyone else run across this issue.

 

Is the heater temperature staying constant? If so, it may be a flaky sending unit. If not, it may need a new thermostat.

 

heater temp stays constant. will look into sending unit. any idea where it is on 4.6? may go ahead while in there and change thermostat to be on safe side.

 

im having the same problem on my 04 4.6. how would i go about checking if its my thermostat? if i squeeze the top radiator hose i can hear the thermostat open and close but im not sure if thats a good thing or not???

 

Are you sure it's your thermostat? That would be unusual indeed. Sounds like the spring is broken. I've NEVER heard a thermostat open and close under any circumstances.

 

i was thinking the same thing. Ive researched allot about the thermostat and not one time have i read its suppose to do that. i checked it when the truck was cooled down and when i squeeze the upper radiator hose i can here it open and close. does anyone have any instructions on how to replace the thermostat? i would also have to drain and refill the radiator correct?