Engine cooling system problem!

Well well well.... this truck is driving me nuts pretty much everything has been replaced except a few odd parts. I am now stuck with another nice issue after getting it running it has still been nothing but problems. It runs well but the cooling system is not working.

I hooked up the mechanical fan now and it still wont stay cool. Ok so what is going on, the lower rad hose is completely empty or feels like it. The upper is full and gets hot when the motor is running. When the motor is running with the rad cap off the liquid is more or less still. I pulled out the thermostat and put it in a cup of how water and it opened up about 1 or 2 mm. What do you think is the problem? If it is the water pump I am going to be seriously pissed off....

How could I determine if it is the water pump?

Zac

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I'll pick up a new thermo tommorow and try it. I don't wanna put it togeather and have to pull it apart if it works so I will just try this out with a new thermo.

Thanks for the help man.

Zac

Well we have determined that we are definitely getting a wrong reading on the temperature gauge. What sensor controls this and what would cause it to go up all the way. Right after starting it it quickly rises to beyond the top of the hot mark on the gauge. I want to check the sensor to see if maybe the wires are reversed or something but don't know what sensor provides this reading.

Zac

The one right beside the T stat Its only 1 wire (yellow I think) so you cant get it wrong.

Anyone got a pic I don't see any wires there...

Zac

theres a sensor on the underside of the intake. Idk if thats the right sensor, but when we took it out of my buddys truck coolant started coming out so I would assume thats the right sensor.

Well, theres also another sensor at the bottom of the radiator, but I dunno what that one does...

Ill get you one later today its to dark out right now

Yea I know there is the one on the rad, it doesn't do much, I pulled the wires and nothing happened that I could see I think it might be the overheat sensor or something.

Zac