jonneyboy25

Truck is a 2005 F150 XL 4.2L


I have no idea on what else i can replace

I have replaced the thermostat, the radiator, the EHT sensor

Radiator shop said they pressure tested it and the head gaskets are good...water pump is good...Fan Clutch is good

They put a new radiator in it and ran it up the highway and the gauge was reading hot so they pulled it back in the shop with a thermal gun and the hottest it was reading was 201 degree 190s in some areas..

No one seems to know whats going on with it

but it makes me nervous driving it with it going from normal to hot back to normal all the time

Doesnt start reading hot until 20 mins of driving???

Davidmackv

Maybe gauge is bad?

jonneyboy25

you would think if the gauge is bad it wouldn't move at all? in my case it goes from normal to hot and back to normal...It does it gradually not all at once???

JCR 56

Well if it's not actually running hot it would have to be the gauge or the wiring to the gauge seems to me.

Spanky666

Question. Does the truck begin to idle badly as the temp goes up? If so, it could be as simple as a bad temp sensor telling the computer that it's hotter than it really is and starts to lean out the fuel. My truck (98 ford f150 4.6) has two sensors. One on the block, one near or on the radiator. Not sure about yours.

If no, then I'd look for a short in the wiring if your engine isn't actually over-heating. But I'd suspect temp sensors first unless you've been slicing wires or have extremely dry-rotted wires. Can always pull a spark plug if unsure. White means lean, black means rich.