3406E Temperature

Your engine if the thermostats are working correctly. Should run from 185-190 cruise. When under a pull could go all the way to 216 then fan should engage. Fan is programmed in the ECM to come on at 216.

 

The dash gauges on most trucks are not very accurate.

The stock 2WS thermostats start to open at 190*F, but are not completely open until 198*F. They are both slow to open and close to keep from thermal shocking the motor with quick temperature changes. The fan comes on at 217*F and shuts off at 205*F. If the gauge is fairly accurate I would expect to see 195*F to 200*F on a hot summer day while cruising a road speeds.