so im almost at the end of getting my 94 dakota back on the road, its been sitting for about 4 years. it was my dads old truck but it didnt start on him one day so he just said screw and went out and bought a new dakota. but we changed a bunch of corroded wires and splices. found out one of the fuel pump wires was cut somehow or corroded. after that i changed both the crankshaft and cam position sensors and cleaned the throttle body. and she starts up and runs good. sounds awesome for a bit. and than the engine noise suddenly changes after its driven for a few minutes? like its gets really quite and doesn't really sound the best? so i looked at the temp gauge and its never come off of cold. it just sits at the bottom? i have sat there and revved it until it sounded different and let it idle for about 15 minutes and it didn't come off of cold?

 

Maybe thermostat, or temp sender?? Does the heater blow hot?

 

hmm idk i'll go check

 

Yes the heater does blow hot! it took a little while but it hasnt been used for a bit. and the tamp gauge still stays at the bottem

 

check your coolant temp sending unit; it's on the left side of the thermostat with a single purple/yellow wire attached to it. Best way to check if the gauge still works is to unplug the sending unit while the truck is running. If it goes all the up to "H", then your wiring is OK but need a new sending unit. If it stay at "C", you have a short to ground somewhere between the sending unit and the gauge in your dash. To make sure that you aren't overheating your truck, if you have access to an infared thermometer, point it in the direction of the radiator hoses and/or engine, should be around 180-200 degrees Farenheit.

 

this may be a stupid question, but where is the thermostat exactly?

 

Follow the radiator hose to the engine. That hose connects to the thermostat housing.

 

That is actually 100% the opposite.
As the engine coolant temperature rises, the resistance on the sending unit will lower, which will send the gauge FROM "cold" TO "hot".

You do not need to have the truck running (it's kind of unsafe to be doing this with the engine running). With the key in the run position (engine not running), disconnect the connector to the sending unit (as stated, on the passenger side of the upper radiator hose, it has 1 wire running to it).

With it disconnected, the gauge should read nothing at all.
Now, jumper-wire the electrical connector to a good ground. Than, the gauge should read full hot.