Temperature gauge doesnt work

Reasons the Temperature Gauge Reads High

If the temperature gauge reads high, it could mean your engine is overheating. Another reason your reading might be high is you could be losing coolant. A small leak or evaporation may cause your radiator to slowly lose coolant. A third reason your temperature gauge reads high could be because the thermostat is broken. If this is the case, you may need a coolant temperature switch replacement. The last reason the temperature gauge could read high is because of a water pump, or water pump gasket failure. If the water pump is malfunctioning, it may need to be replaced by a professional.

What to Do If Your Temperature Gauge is High

If your temperature gauge is reading high, it means your car is overheating. This is a very serious matter and you should never drive an overheating car. If your car starts to overheat, shut off the air conditioner and open the windows immediately. If this does not reduce the overheating, turn on the heater as high as it can go. If this still doesn't work, pull over on the side of the road, turn off the engine, open the hood carefully, and wait until the vehicle cools down. Never open the radiator cap while the engine is hot - coolant can spray and burn you. Once the vehicle has cooled, take the car to a mechanic right away so they can diagnose the problem. Cars are especially susceptible to overheating in hot climates, like what's common in cities like Los Angeles, Phoenix, Las Vegas, or Atlanta.
The temperature gauge is an important tool in your vehicle that shows the temperature of your engine's coolant. Contact YourMechanic and have your car inspected for overheating if it reads too high, as this can cause serious problems...

Reasons the Temperature Gauge Reads Cold

On most vehicles, the temperature gauge reads cold until the engine has run for a few minutes. If the temperature gauge still reads cold after the engine has warmed up, the gauge may simply be broken. Another reason the temperature gauge could read cold is if the thermostat in the vehicle stays open. With the thermostat stuck open, the engine can be overcooled, causing a low temperature reading. If this is the case, the thermostat may need to be replaced.

Its possible that you got a faulty thermostat that is actually sticking open and not allowing the water to actually heat up to temperature. Try checking the heater and see if you actually have heat. If not, I would start there and purchase another thermostat. It's the cheapest route and I have purchased bad ones myself.

1) Is it really running hot, or is the temperature sending unit or gauge incorrect? You could use an alternate temperature sensor to test - infrared temperature gauge.
2) Just because the radiator was cleaned out doesn't mean it isnt blocked. Check to see that water will flow through the radiator.

check for the alternator failure. probably not charging.

Check the radiator and the cooling fan. open the hood as the engine temperature rises does the fan come on. if not that the problem, Also do this As the car is warming up(from a cold start) near operating temperature, turn off the car, watch out for the fan, engine of key in your pocket fell the radiator is there any hot or cold spot? if there is the radiator is plugged. Also if the radiator isnt plugged new doesnt mean it works, the water pump itself can be faulty. and dont forget the most important device the Thermostat you did timing belt waterpump they should of done thermostat.

leave well alone it runs and doesnt overheat ,thermostats come with different temperature ranges ,82?c to 98?c average is 88?c or 92?c ,dont interfere with it leave it alone its fine

Ok well there are a number of possibilities. One to keep in mind is that some water pumps are really cheap and the fins will corrode and rust off leaving nothing behind to actually pump the water. If the pump really is working fine then there are two more possibilities. 1 the radiator is clogged, 2. there may be a head gasket leak. 3. you are sure your gauge is working right? 4. you didnt say what year or kind of car it is.. Is the electric fan working? When the engine is overheating, are both upper and lower radiator hoses hot? If the water pump or the thermostat are failing the upper radiator hose can be hot while the lower can still be relativly cool. If the radiator is plugged or the fan isnt working then both hoses can be Hot. There is also a remote possibility that water passages in the head gasket could be plugged.

It sounds like you have air in the Cooling system and the bars leak permanent seal does not help. The sealer creates restrictions through out the water jackets and can cause the thermostat to stick. Replace the radiator cap and run the truck with the radiator cap on the first click and keep an eye on the over flow tank, refill the over flow as needed and make sure you have the heater on the highest setting to work out all the air in the system. Once all the air has worked it's way out of the system, then you can close the radiator cap to the second click to ensure full pressure is built up in your cooling system. Good luck and keep me posted.

how is the radiator and the thermostat?  Do the cooling fans come on?  Are you totally filling the cooling system and bleeding it?

The radiator cap is at the radiator where you refill the radiator with coolant. Unless it is leaking and you hear a hiss. It may not have anything wrong.Neither will the water pump.If the water pump is bad. It has a small hole that will make it start leaking .Check the engine for leaks at the intake or the water pump.You will know where it is leaking. When the thermostat was removed and hopefully replaced , did you bleed the system ? The system has to be bled to remove air pockets. Or the engine will overheat again. Also check that the radiator fan or fans is turning on . If not you may need to replace the temperature control sensor.(TPS)