ernest t bass

on a hot humid day last week i drove my 1993 3.0 2wd automatic xtracab with the a/c on up to jamul from san diego. not much of a climb. after stopping at my appointment i returned to a temp guage that was almost at the red line. once running it started to cool down almost right away. did it again to day in escondido. 95 degrees and humid like last week. truck has just had a new fan clutch. more recently radiator checked out ok by radiator shop,new coolant too. are these guages junk or do i have other problems.

mt_goat

That sounds like heat soak, when you shut down the engine the heads are still very hot and it gets the coolant near them very hot. The temp sensor is getting hit with that very hot coolant that soaked up all that heat while the engine was shut down. Then as soon as the coolant starts flowing through the radiator again it cools off.

The temp gauges on these trucks are basicly like a fancy idiot light. Mine shows prefectly normal (middle of range) from about 175-235 F then after 235 it will start climbing above the middle of the gauge.

You're most likely running in the upper end of that range and shutting down sends it over the edge into a danger zone. Be very careful the 3.0 head gasket is very prone to blowing when over heating. How old is your radiator?