so i just put a new engine in my 4runner about 3 thousand miles ago, and the other day it started doing something funky.

when i start the truck being cold, it runs great, i start driving and the truck heats up to normal temperature. after being normal temperature for about 5 min the temp gauge starts working it's way up to almost the red line and about a minute later it jumps back down to where it should be. after that it will have no issues until the next time i start it being cold.

any ideas whats going on?

222re 5spd 1991 4runner sr5

 

Have a look below:
- http://www.4crawler.com/4x4/CheapTri...tml#Thermostat