Anyone know of a way to test the temp guage on a 99 24 valve? My guage doesnt seem to be working. It will move up from all the way cold but barely moves at all.

Also, where is the sending unit for the guage? I think I see in on the front top of the motor right next to where the upper radiator hose goes in.

I don't think it's the t-stat, becuase after driving for a little bit, with the temp guage having not moved at all from the full cold position, the heater will blow heat into the cab. It's not very cold here yet though,...

I gave the cooling system a full flush a few months ago.

Thanks
Matt