Water pump
6 Answers
Also if the wire to the temp sensor just happened to come loose and is touching metal your gauge will do this. But if when you turn key on it goes all the way to hot then drops back to cold and then gradually climbs back to hot it's not a wire issue. Check your work. Make sure that you got all the air out of the system. An air pocket will cause it to do this also.
Sounds like a thermostat is stuck shut when u crank the truck watch the temp gauge it should move to the hot position then the needle should go back to normal if it doesn't work u need a coolant temperature switch forthe gauge u may want to check the coolant sensor by the thermostat housing that is the one for computer and signals when the thermostat opens take the thermostat out put it back together then run it to c if it overheats
To check a therm remove it from vehicle. Place it and a cooking thermometer in a pot of water and turn burner to high. According to what temp therm you have (175-185-195) you should see it start to open when water reaches this temp. It should completely open. Then use pliers to remove it and place it under cold water. It should completely close. (Call your local auto parts to see about what temp therm should be in your vehicle) If it operates normal re install it. If it does not replace it.
No no but when I fill water on the radiator it has bubbles and it became full after a while it going down.
Ok sounds like air pockets. Open radiator cap and let it idle for a bit while adding water as it goes down. Not sure about your model but some have air bleeder valves in the cooling system that you open while filling it with coolant. And when coolant comes out the valve you close it and all the air is out. But after all this and you think that all the air is out but it's still bubbling I would check for blown head gasket. Get test kit to test coolant for exhaust gases. Check oil. Does it look like a milkshake? If either answer is yes then head gasket blown. Can also pressure test the system. If system will not hold proper pressure then look for where coolant is going.
