oldblu

Hey,
i'll be driving a long the hwy and notice my truck is getting cold cause the heater quit putting out heat, then look down at my temp gauge and its going crazy. It will go from 190 or so to pegged all at once any ideas guys. Then shut the heater off and it is fine in a bit thanks

tryNto

low on coolant, bad thermostat... check the level when cold at the radiator, may need a new cap...

johndeere01

mine would climb almost to the red fast an then drop to below 210 an then back up to the red really fast when my water pump went.

jfdid

Make sure to check your rad cap(just replace it) and make sure the overflow tube is connected without leaks, and clear of debris. I had a similar issue and the tube wasn't completely connected, it ended up leaking coolant out when the truck would warm up, then would suck in air instead of coolant. Such is life.
Let us know what you found.