I started up my 2008 F-250 6.4L as I was preparing to leave work and the engine coolant needle pegged out and the hot coolant icon appeared on the user information screen. My H&S Mini Maxx also indicated hot coolant even though the truck had been off for 12 hours. I checked the coolant level and it was normal/full. I drove the truck home and everything seemed normal except the radiator fan was engaging like I imagine it should if the truck thought the coolant was hot. The Mini Maxx showed a coolant temp of 280F +/- a degree the whole time I think. The oil temp stayed normal at 203F +/- a degree so I figured my ECT Sensor must be bad. I have a feeling it's in a hard to get to spot. I checked the Mini Maxx for any Engine DTCs when I got home and none were found. Does anyone have any experience in this? Is it probably just a bad $35 sensor? How hard is it to replace? Thanks for any advise,
Clint

 

Pretty sure its on the front of engine right above the water pump pulley

 

I believe I found it on the thermostat housing under the radiator hose connection. Having a problem finding a new sensor on a Sunday holiday weekend...

 

I think you are pretty much on the mark.
This spring I had a similar issue, except my fan rarely engaged. The hot needle would peg then slowly return to normal when I pulled over. This only happened when towing a 5'er.
My tech chased it down to the following:
Temp sensor, by the thermostats (not a 60's rock hit)
Thermostats x 2, these are a nightmare to get to, as well as the temp sensor.
Lower radiator hose, new and improved by Ford (two "O" ring style)
New Ford fluid and a $1000 bill for labor @ $70 per hr.
Parts were relatively cheap.
Problem solved, I feel lucky.

All the best

 

Just had to replace the ECT Sensor and everything is back to normal. It was a PITA to get to. It's just to the driver side of the power steering pump at the base of the thermostat housing. Right behind the hose that connects the power steering pump and reservoir. It was the hardest I've ever worked to replace a $20 part. Replaced the belts, tensioners & idler pulleys while I was there. Just rolled over 190,000 miles.


Thanks to slowmans & JR58 for the input!
Clint

 

Glad you got it done!! Have you had any major problems in with that many miles?

 

Not much really...


I had a misadventure with mixed universal green antifreeze and Ford Gold (from a tire shop oil change). They didn't play well together and the oil cooler had to be replaced from gelling up (cab off job). I did some phase replacement on wearable items when the cab was off.


I had to have the Transmission Valve Body Wiring Harness replaced. It was pinched when it was installed at the factory and the insulation finally broke down.


Other than that just regular stuff...trans fluid changed twice, belts/tensioners changed twice (idlers once), radiator hoses once (mine is an 08' Job 1 so I had the old hoses), thermostats once, batteries twice, oil every 5K miles (usually but I have gone as long as 7K miles) with Blackstone reports starting around 70K miles, fuel filters every other oil change, replaced CAC hoses with B&D hoses & clamps, replaced brake pads once (with Motorcraft), and the Engine Coolant Temp Sensor...


Deleted the Cat, DPF & Resonator at 70K miles after the warranty was gone. I installed a Banks Dual Exhaust & MBRP Delete Pipe. I run an H&S Mini Maxx set on No Power Added. I use the factory air box and factory air filters (don't trust aftermarket CAIs as they might dust the engine). Always used Ford filters.


I need to replace the diff oil, transfer case oil, trans fluid (again), brake fluid and power steering fluid just due to miles.


I love my truck, but if I let my mind wander too long I do get a bit scared of what could happen...but I think I have one of the good ones.




How about you Slowmans? Any problems?