Today, we pulled our 5th wheel camper home after a trip to the Smokey Mountains. We traveled about 270 miles. It is tricky getting unto our yard and I tried something different. We live in the Ozark Mountains in Arkansas and everything is hills. I have to back up my driveway. Instead of maneuvering into position at the base of my driveway, I turned onto our street a block down the street and backed up the street and into my driveway. So I was backing about 500 feet up hill. Before I got to the top of the hill, I smelled antifreeze and there was steam coming out from under the engine hood. Engine and transmission temps were normal in the mid gage position.
What do y'all think was happening? Thanks!

 

It shouldn't have happened, but check the cap on the coolant reservoir and make sure it is tight. Backing up that far with that weight used to kill the 4R100 transmissions of old, but never heard of coolant issues with the 6.7s. There are bad O-rings on some of the radiator hoses out there though. Maybe it is that simple. Maybe some one else here can shed some light. Definitely interested in the root of the problem though.

 

Thanks Monty. It had been raining, so I couldn't tell if there was any antifreeze spilling or spewing out. It was a long day and I'll check some more tomorrow.

 

At first glance, look to see which coolant reservoir looks low of coolant. The radiator or the exhaust side one(smaller). That will give a direction to start with.

 

One thing to consider is that long backups tend to heat up brakes, many folks have a habit of dragging the brake pedal while backing. I've smelled many burnt brake pads ( truck and trailer ) watching folks back long distance.

 

When cold not only check the fluids but look for coolant splatter around the degas bottle and radiator/hoses. Unless turning could you back up in 4lo?

 

Unless Ford does it different the cooler for the trans is a radiator and on a long back up, especially up a steep hill things can overheat FAST.

I was leading a run of about 8 Jeeps in Moab Ut few years back and we had stopped at the base of a VERY tall, long and especially steep hill. I am giving a safety briefing to my folks when a Hummer pulls up belonging to one of the tourist places that takes folks on runs out there. It had about 8 folks in the adapted back of the Hummer and he stops, gets out and asks if he can go ahead of us. I said sure, you are only 1 vehicle and there are 9 Jeeps.

He turns to the folks in the back of his Hummer and says I am gonna show these Jeep folks how its done. He turns around and proceeds to back up the hill. About ½ way steam and green fluid are coming out from the front end. He is to far way to hear us yelling and I guess he is focused on going up...a little before the top the trans just PUKES and its oil and grayish-black smoke from under the Hummer.

Long steep backs are very hard on your trans and also hard on your axles. You can starve the pinion bearing on the font axle which can lead to premature failure...

 

With my Edge Insight I have noticed that the coolant temp gauge pretty much stays in the middle when the coolant temp is anywhere from 160 to 215 degrees. Is it possible that a coolant reservoir (degas bottle) cap not holding pressure would allow the coolant to boil and vent at around 212 degrees while the gauge showed "normal" temperatures? Just a thought (and possibly a cheap fix). I just recently replaced mine when I noticed my upper radiator hose was collapsed in the morning.

 

Thanks for the replies, y'all. It rained all day and I didn't get a chance to check anything. Sounds like my plan to back up the longer distance was not a good one. However, I have to be able to back it up about 200 feet. I could park at the bottom of the driveway and let the truck cool down, then back it up a couple of hours later. Would it help if I had an electric fan blowing on the transmission cooler when backing up the hill?
I don't have 4 wheel drive, so there is no using 4 low. I wish I did have 4 wheel drive.

 

The trans cooler on these trucks doesn't use the standard "air to fluid" like the previous trucks had. The 6.7 uses only coolant from the secondary cooling system to remove heat from the fluid. This is extremely beneficial to heavy operation at low speeds where not much air is being pulled across the radiators. The secondary cooling systems runs extremely cool and can handle the demands of various low speed operation. Hope this helps.

 

Thanks UGA33. So, if I understand what you said, an electric fan will not help.

 

No, the heat exchanger is a little box with coolant lines and trains fluid lines passing by each other. There's no forced air or heat to air transfer outside of the exterior surface area of the trains itself.

 

Look under the passenger frame rail near the bumper.

 

OK, guys, from the technical aspect; what is producing the heat? Is a clutch slipping? Pumping extreme fluid pressures? Would it be better to back slowly or faster? Would a truck with 4 wheel drive be able to do it in 4 low without straying the whole system?
Thanks for the replies.

 

Are we talking about engine or transmission here? If you smelled antifreeze I would start there instead of the transmission.

The majority of transmission heat is caused by the torque converter. Automatic transmissions don't use a conventional clutch like manuals do, but rather a fluid coupling called a torque converter. When applying power at low speeds the converter isn't locked which transfers all of your power from the impeller to the turbine in the converter through the transmission fluid. This applies a huge shearing force to the fluid and causes it to heat up rapidly.

Basic Torque Converters - HowStuffWorks

Backing a trailer up in reverse is hard on the cooling system because you don't have any airflow over the radiators. As long as the fan clutch engages correctly this shouldn't be a problem, and I'm a little surprised you had an issue without your gauges moving.