Sensors for coolant temperature gauges are notoriously inaccurate, and no two are the same. What you're watching for is when the gauge indicates differently than what you have come to know as "normal". I have four Dodge Grand Caravans. One always reads 1/4 scale unless I pull my really big tandem axle enclosed trailer, then it can get up to 3/4 scale. One of the other van's gauge always reads about 5/8 scale.
To know for sure what the coolant temperature is you have to connect a scanner to view live data. The Engine Computer uses a different temperature sensor that IS pretty accurate. If you find that is showing the correct temperature, what you see now on the dash gauge is your new "normal". If you really want the gauge to read the same as it once did, you'll have to buy a dozen sensors, then install them one at a time until you find the one that gives you the reading you like.
Some dash gauges did have mechanical adjustments for the pointer's position and for the "spread", or range it swept through from low to high. Those were adjusted at the factory and rarely needed to be readjusted after that. Your gauges should be computer-controlled, and the computer is going to place the pointer based on the sensor reading.
Sunday, July 20th, 2014 AT 8:50 PM