Temp Gauge not workin..

my tempature gauge has been out for quite a while now. The gauge is all the way down for about the first 10 minutes of driving, then after that it slowly rises but it doesnt mark right. I dont like not knowing the temp of my car. I can feel the car getting hot but it doesnt mark correctly so i try to make all my trips 15 min or less. The mechanic said its an electrical problem, are they expensive to get fixed?

Also my coolant is real dirty, will dirty coolant cause the car to run hot? im gonna drain it, what type of coolant you guys recommend?

1.) Sensor
2.) The green stuff

Which one would it be? Air Charge Tempature Sensor or Air Cleaner Tempature Sensor?

Which one would it be? Air Charge Tempature Sensor or Air Cleaner Tempature Sensor?

it could be the Coolant Temp. sensor...located between cylinders 1 and 3. nothin to do w/ air temp.

had the coolant temp sensor changed last november, still didnt work. any other suggestions?

there are two coolant temp sensors. One for the computer and one for the gauge.

the one that runs the gauge is in the drivers side head between cyl 1 and 2. make sure the wire is on the end of it. it's a green wire on my 87. if it is then replace the sensor.

Hodge

had the coolant temp sensor changed last november, still didnt work. any other suggestions?

This is a single wire sensor no teflon tape, or sealer of any kind is required, because the body of the sensor is used to complete the circuit to ground.

Are you having any other electrical problems, check the ground strap connecting the driver side cylinder head to the firewall.

Like was said above, the sender that runs the gague is in the driver's side cylinder head under the exhaust manifold between cylinders 1&3 (front 2 cylinders). To test the gague unplug the wire from that sensor and ground it out against the engine wherever's convenient. When you ground it the gague should peg full-hot. If it does, it's not the gague or the wiring- it's the sender.