YotaSmith15

98 toyota tacoma 4 cyl automatic 4x4 ... start truck up and everything runs fine but once truck idels for few mins temp gauge goes to about half, drive 3-5 mins them needle jumps up to the H, let off the gas pedal and needle drops back to half until I push on gas then back up ... I then can put truck in park and it will stay at half, put foot on brake and put truck in drive without pushing gas and needle goes to H .... took waterpump off and it looks good so put it back, replace thermostat and coolant temp sensor, drained water out bottom on radiator and refilled also, top of radiator gets hot and top hose gets hot also but bottom hose you can hold onto without it getting really hot, any suggestions on what can be the problem?

maachine

sounds like there is no circulation running through the radiator. you either have a plugged radiator or an air bubble in the system somewhere.

rworegon

What's the status of the fan clutch? Is there a wiring issue?