Have you tested the coolant temp sender? You might not be overheating, but the sender is telling the gauge you are.

 

I am with Leeann, have you verified that you are really overheating? It could be the wiring grounding out...

 

well turned the truck on just now and the gauge was acting normal. It got up to normal operating temp then went past and up into the warning zone. It went back and forth between the warning area and just before that for a few minutes then just stayed in the warning zone. After i turned it off i could hear some bubbling or something inside the rad. Does this mean there is still air in it or just that the coolant is really hot and bubbling. The top hose was hot, but all the other hoses like the lower hose and the ones running to the heater core were all cold. Also how would i go about checking the temp sender? Any advice helps...getting a bit frustrated now...

 

Bubbling/gurgling usually means air.

 

Also clean out the water outlet to the heater core.

 

so i just went out and bypassed the heater core and i was bleeding the system of air when the gauge started messing up. It was working good and the temp got up to normal then the level went down so i shut it off to refill and cool down and do it again. After leaving it for about 30-40min to cool off i topped up the rad and started it up and the temp gauge jumps up into the warning zone and "check gauges" lights up. After letting it run a bit again for the air to escape i shut it off and filled up the rad once again. then i had to move it back up the driveway and the gauge worked and said it was at normal operating temp, then a few seconds later it jumps right back up to the warning zone. So where is the temp sensor/sender so i can take a look and replace them from my jimmy if needed. Need an accurate temp reading to diagnosis the overheating problem if there even is one now...

Thanks for all the help....

 

It's a single wire sender on the head. Mine is on the pass side.

 

i don't work on car and i don't really know much. but my car had the same problem i wasted so much money on work that they thought was wrong. but it was still the same. until i last my radiator cap putting coolant and replace it cap it stop overheating weird but works haven't had to do anything to it since