What year is your truck?

 

2005 crew cab 4.7 non HO, 82k miles

 

Try running @ 80mph w/the OD locked out, see what you get compared to your previous.
OAT? Engine temp? RPM?

 

I already added fan back yesterday and drove 6 hours. Still ran in the middle and sometimes slightly above. Even though i have a 180 deg thermostat. Only dropped to below half way mark when turned off ac and slowed to 45 and stopped at several red lights in 85 deg weather. Seems to me the ac coil is heat soaking the radiator. I was mostly running the air on recirc and the 1st or second fan speed setting.

Edit i was turning on tow/Haul on hill climbs and off during decent as it would lose 5 mph on hill climb without downshifting.

 

Lowering the opening temperature of your thermostat can cause serious damage down the road.

 

Have you compared the reading on your dash gauge w/an IR non contact thermometer? Or other confirmation of engine temperature?

 

I checked it last week with ir thermo after installing 180 thermo, waterpump, and flushing. Just to be sure the thermo opened when it got up to temp. I'll have the recheck it next week when i get back home. But the temp gauge seems consistent in its location vs driving parameters. 3 hr drive tomorrow but dont know if taking slower scenic or highway route.

Gauge stayed in same area for 6 hrs of driving, dropped lower for next 6 hrs after fan reinstall, and again dropped the last 45 mins when i slowed down and turned off a/c.

 

Last update. Been back for 1.5 weeks. Truck ran fine the 900 miles back home. Although it was in the 70's to mid 80's the whole way back unlike the 90's on the first leg of trip.

Havent lost any coolant. Fan is stiff to turn when cold. Used infrared thermometer checking real quick after truck shut off and a/c off the previous 5 mins. Radiator seems to have a steady temp drop from 185 to 160(dont remember exact numbers). Truck will idle at 180 all day with ac on. Giving up any further trouble shooting. If it runs hot again next step would be aftermarket radiator(from where?).

 

I have experienced the cooling woes as well. With my 4.7 and original semi scaled radiator, I could reach above half a few times during the summer. I switched to the HHR efan and actually had a very bad time, it always got hotter and then it blew up on me in traffic and nearly fried mt 4.7

With the cammed 5.7, same but new radiator, and the mechanical fan, it would climb well above half in summer temps. For my 5.7 Dakota, I cool it with the stock radiator and a Ford junkyard fan that pulls an estimated 4500cfm. It never goes above half, that's for sure and stays well below it. I use 180 tstat, a volvo 2 speed relay, with a BMW dual temp switch. Switches low at 75c and high at 91c. Best cooling to date...