1989 Comanche 4.0, Pioneer pkg. Running hot according to temp gauge but not in red. Without AC on, temp climbs slower but eventually goes past 210 mark on gauge. Had also bypassed the thermal switch in radiator with a jumper so that auxiliary fan runs all the time.
Thoroughly cleaned cooling system and replaced thermostat, auxiliary fan switch in radiator, sender for temp gauge and a couple of hoses. Looking into head through thermostat opening, everything is clean and I have reason to believe radiator is too. No head gasket problems. No leaks. No restrictions of air flow through radiator and condenser. Engine temp slowly increases past the 210 mark on temp gauge in stop and go city driving and on highway. Hasn't gone into red zone on gauge yet but if accurate, must be about 225 degrees. Not comfortable with it running that hot.
Have driven AMC's with inline 6's for 40 years and never had an overheat problem with everything clean and in good shape. A slight increase in engine temp is expected when air temp climbs into the 90s but not this much.
I noticed that the senders for the temp gauges on older engines have been located at the front of the head below and to the right of the thermostat housing. On my Jeep, the sender is directly above the #6 exhaust port on top of the head. Not much room between the sender bulb and the water jacket wall above the exhaust port. Temp readings taken with infrared pistol grip type thermometer seem to indicate normal operating temps at front of engine, on hoses and radiator. However back at the sender, the temp reading is much higher. Almost 30 to 40 degrees. Radiator shows only a 10 degree drop from one end to the other with the AC on. Lately we have had air temps near 100.
Questions: It has been recommended that I install a new radiator mostly due to age but before I do that, has anyone else with this engine experienced this much extra heating in the summer months and cured it with a new radiator? Could I be getting a false reading on the dash temp gauge due to the location of the sender? Is my engine really running that hot? Thanks.