False overheating

[J. Gehret]

Here's the details, 03 exploder 4.6 awd. Just replaced the intake manifold due to the common leak at the thermostat housing. The problem occurred before the intake was replaced and I chalked it up to air in the system. Now that I've replaced the manifold I still get the same results.

System fully burped, degas bottle in the full range. Start truck and instantly the temp gauge goes up a little bit. Go for a nice 20 mile drive, hot heat from the vents, temp gauge runs a little below half way. Get home, shut truck off and restart and temp gauge pegs high and comes down to normal within 30 seconds. Infrared gun shows 198 at the thermostat housing....however my scan tool shows the coolant temp to be 230

I tried and experiment last night. Truck sat all day, ambient air temp was 81. I turned the key on and the temp gauge went up a little. Infrared gun on the thermostat housing read 83. Scanner plugged in, key on engine off shows a coolant temp of 124??? 40 degree difference, there's obviously a false reading here.

I'm not one to just throw parts at a vehicle in hopes of making a repair. From the above data it seems to me I have a faulty cht sensor. I don't think I have a pinched wire since the problem was occurring before the new intake was installed. Any input or advice is greatly appreciated.

Oh, on a side note. Dorman is full of poop. The intake they say won't fit on a 4.6 with the heated pcv works just fine.

 

[shadowless127]

I would go ahead and replace the sensor. The fact the truck sat and the computer is reporting 124 screams faulty sensor.