I need some help here. Seems the dealership and Ford are clueless on this issue...

I have an 08 F450, 4600 miles - most of which is towing mileage. Normally I'm towing a 2 horse trailer, just about 4000lbs. I have had as much as 12,000lbs on it - and it tows like a dream. I've driven as far as 5 hours on the highway towing with no trouble - that is until a few weeks ago.

I was running up the highway towing my horse trailer, just one horse in it, about 4000lbs. About 40mins into the drive (at 70-80mph most of the way), the truck overheated. I'm not talking about getting above normal here - I'm talking about all the way in the red zone, digital warning light on and all. It was about 90 degrees outside, I was driving with the AC on. I cut the AC, rolled down the windows and turned on the heater - which, within a few minutes, cooled the engine to "normal". I wanted to make sure it wasn't just a one-time thing, so closed windows back up, turned AC back on and within 5 minutes it was back to HOT again. I drove the rest of the way (another 10 mins) to my destination with the heat on - engine at normal with the heat on (lots of fun in the humid summer heat!). After letting the truck sit for several hours and speaking with Ford - I verified that the truck was full on fluid and attempted to drive the truck home - as I didn't want to be stranded with my horse in the trailer. I didn't get 10 miles down the road and the "Check Engine" light came on on orange. The truck was not overheating at that point, but decided not to risk damaging anything and called for a tow.

The dealership had the truck for 3 weeks, and were never able to get it to overheat. There were no service codes relating to the overheat on the computer when I brought it in. After about 2 weeks the service manager went to drive it and discovered it running roughly - turned out to be a major transmission problem - it was stuck in lower gears and would not shift up. Now I was pretty sure I would have noticed if it were stuck in a low gear - but since they couldn't find anything else, I was willing to accept that it must have been the problem from the beginning. They fixed the transmission and I picked up the truck.

The day after picking it up - I headed for a 1 1/2 hour trip to see the hoof specialist with one of my horses. I got down there no problem, paying special attention to rpm's and things like that as I drove. I headed back towards home, driving conditions identical to the trip there - 65-80mph most of the way on the highway. More than an hour into the drive, the truck started overheating again - needle all the way in the red - I checked the rpms, never went over 3000 on the guage. I was again able to bleed the heat off the engine using the truck's heater (another 90 degree day I should add). I immediately called the dealership and spoke with the service manager (who was of no help). I asked them to send someone down to look at it while it was overheating - but they refused, and I had a horse in tow and was at least 45min from the dealership - so no way I could drive it to them. I drove the last 15mins to my house with the heat on (which brought temps back to normal while it was on, but would shoot right back up if I turned it off). The dealership came down and picked the truck up the next day - but now tell me they can't make it overheat and want to borrow my trailer to see if they can duplicate the problem.

This is extremely frustrating and wanted to see if anyone has had this problem or have any suggestions.

FYI - when trailering, I use the tow/haul button for back roads but turn it off when I'm on the highway.

 

If i didn't know better i would say it sounds like a thermostat problem or a fan issue, but their all still alot of others possibility's without being able to check some other items like the fan operation, cleanleness of the radiator for proper air flow, turbo boost leaks which would over work the engine due to lack of power ect.

I've towed at 20,000 lbs GCVW out of laughlin NV when the temps were 118 and the grade was 5 to 6 percent for twenty miles and iv never had a heating issue. I think this is the first iv seen.

I sure you have checked this but i know there is a TSB out on coolant leak that i think has to due with the radiator, the cooling system could be low or cooling system pressure could be way low. Just a thought.

 

The VERY first thing I did was to check the coolant levels. The truck is BRAND NEW - less than 5,000 miles - so dirt can't possibly be bult up anywhere yet, it's never even been on a dirt road, nothing but highway driving and getting to and from the highway.

I made sure to check the fan - and it was definitely running when it was overheating - of course I'm not about to put my hand in there to see if there's resistance or not however.

Seems to me that if it were the thermostat it would head up within the first 1/2 hour or less of driving, not all the sudden after an hour of driving?

As for the turbo boost leaks - there was no loss of performance on this truck.

 

Its odd the heater will cool down the truck, which lead me to believe that the thermostat might not be working proper. After an hour of driving the truck is heat saturated and requires for effort to cool. If the thermostat is partialy open it would take longer to heat up and wont cool if it cant fully open. The heater has a constiant flow which is why i im thinking there is a flow issue. I could be wrong its just a thought.

 

Do you hear the auxiliary fan come on? When towing 17k through the Poconos near the top of the hills, when the auxiliary fan came on it sounded like a 747 flying overhead, it gives it some serious cooling. That could be one reason the dealer can not duplicate the conditions.

 

I have never noticed the sound of a fan, not even when I drove out to Syracuse through the mountains towing 12K lbs. I did, however, stop the truck when it was overheating and confirmed that the fan behind the radiator was spinning.

 

Just took a closer look. Thought it had a second fan, But it does not appear to have. It must just increase to a high RPM. There is no mistake about it when it comes on for extra cooling. It really howls, my wife and I looked at each other 1st time it happened. We really thought it was a jet overhead. When it kicks down it does it slowly comparison when it comes on. Some other owners should be able to tell us more about its function.

 

You will most definitely know when the fan kicks on. The fan will always spin when the engine is running, but it is a variable speed fan. When the engine heats up enough to need the fan, it will fully engage and like they said, it'll sound like a 747. When the fan comes on like it's supposed to, there will be no question as to whether or not it's working. Sounds like your fan may not be kicking on when it's supposed to.

 

I want to thank everyone who gave me input. It really helped me talk with the dealer.

Here's where we're at with it. The dealer was unable to duplicate the problem with just the truck and today looks like the last of the "hot" days until next summer (hopefully). It was back up to 90 today (I'm in MD - it's supposed to be in the 60's) and I knew today was going to be my last chance to get the truck overheating.

The dealer brought the truck down, we hooked up my horse trailer, and within 10 mins of leaving my house it was in the red on the temp gauge. Thanks to all of you, I was listening for the 747 - and nope, note even a single engine prop! We got it back up to the dealership and the mechanic was able to run the diagnostics on it while it was hot and sure enough, the fan was NOT kicking into high speed. Yes, it was turning, but was not turning any faster than it would at simple idol with a cool engine. YIPPEE! We also noticed some oily fluid around the fan shroud and since there has been no odor of anti-freeze, we are assuming it's the fan motor that was blowing fluid out.

The best part, after finally being able to prove to the dealer that it actually did overheat, was that the area Ford rep just happened to be there today too - so I got to gripe in his ear as well.

I think we'll be back on the road now in no time. Thanks again, all - your comments were a HUGE help.