Whats the problem? Was driving on the highway the other day and suddenly the engine temp. instantly went from normal opperating temp. to max. Stayed there for less than a min. and suddenly dropped back to normal and stayed at normal. Iam confused.

It did this while you were driving, and you never shut off the engine?

Only 2 ways that can really happen. One, your low on coolant and you got a air pocket, two, you have a bad temp sensor. This should not be a bad thermostat, they generally stick open and you over cool. And it'* not a obstruction or bad water pump because that would over heat and not cool back down.

never stopped driving

Either bad temp sensor or air pocket.Also what kind of vehicle is this (Make model engine year)

EDIT: I had the same issue on my truck a while back and it was a temp sensor

I'm going to go with the air pocket theory, or you got the thermostat that'* ultra-rare and stuck closed for a minute.

Was this a near instant snap of the gauge or did it gradually go up? If it was near instant, I'd suggest looking over the wiring to the sensor and or replacing the sensor.

BTW....what do you drive?

A horse, duh.

he has a pic of a 1500 on his page, the trucks are different. they have a diff sensor for the dash guage. the one for the guage is driver side of engine by the exh. manifold. they are known to go bad as are the gauge pods. check the wiring first maybe somethings just loose.

Justin is right there is one by the manifold for the and another on the intake manifold right by the thremostat housing..The one by the exhuast manifold will have one wire coming out of it and the one on the intake will have two.although i will say when i had the issue my guage would snap up if i slowed and go back down if i was moving.I had to replace the sensor on the manifold to correct my issue.