I have talked to the service manager at the dealer and they have never heard of this issue before so I thought I would ask here.
I have a 2011 SC 4x4 and I just traded in my boat. I towed my old boat down this road about 8 times with no issues at all but that was only 3.3K lbs with the trailer. Saturday night I was pulling the new boat which is about 2K lbs more than the old one.
The road I was towing down is quite treacherous in spots, in particular there is one hill that actually deters a lot of people from going to this particular lake. On the way out when you pull up the hill it is about 1/2 mile of steep winding dirt road. I had to drop the truck into 4x4 and lock the transmission out of 3-6 to get up the hill due to spinning the back tires. When approaching the top of the hill the transmission temp was at 240 deg (still not in the yellow or red on the gauge) I started hearing a "clunking" noise like the transfer case was engaging and disengaging while the rear tires would lose traction. I could not stop or I would not have made it the last 300 ft to the top. I pulled off the road at the top, took it out of 4x4 and let the transmission cool down. I did not have any more issues all the way home.

Just to check on Sunday night I put the truck in 4x4 on the pavement and ran it up to 40 mph a few times from a stop and there was no noise and it pulled like all 4 were engaged. I went by the dealer today and there are no codes stored (no light ever came on) and they are baffled as to what happened.

Anyone experience similar issues? have any advice? is this the computer protecting the transmission due to the elevated temps?

any help would be greatly appreciated.

 

240 on the trans temp. That's really hot. Highest I have ever had mine was 220 and that was only for a couple seconds. Did you have it in 4hi or 4low.

 

It was in 4 hi

 

I have never heard of the transfer case disengaging in response to transmission heat and not sure why it would. Normally the engine depowers like crazy and will hardly move the truck, in my experience.

Maybe enough slack in the driveline to clunk as the tires fought for traction.

Regardless it sounds like your truck is okay. While 240 is hot, your transmission fluid can live at that temperature for short periods of time without damage. There are tables on the Internet showing fluid life expectancy based on temperature.

 

Sounds like traction control kicking in and out. I have experienced a similar sound when in snow.

 

It's sounds like the traction control to me also. It is still active in 4hi unless you turn it off. In 4low it automatically turns everything off.

 

Check out this thread. Crazy001 has the ecoboost and we towed at 21K combined with it up this hill. We started in 4x4 to go up the hill.

Listen closely to the clunks..is that what you heard?

https://www.ford-trucks.com/forums/1...-hd-video.html

 

That didn't sound good at all. Sounds like it wasn't fully engaged when he took off. My brother had that happen to him when he was a little impatient. It ended up breaking his front driveshaft.

 

Was fully engaged. He had switched it before even stopping for the start of the run so it had rolled several feet engaged before hand.

 

I agree with the traction control going in and out especially with the rear wheels spinning. The next time you climb that hill you should be in 4x4 low. It will keep the tranny cooler and is much easier on the whole drive train and engine.

 

I get a pop/clunk in mine but its the front diff bushings giving in. They just don't hold up very well. I wonder if that could be chain slip inside the t case

 

Hi DJ2,

I want to look into this for you and check out some options to help. I'll need a PM from you with your VIN, dealer, mileage, daytime phone number, and full name; I'll take it from there.

Thanks!

Crystal

 

It's funny you mention that; this was the first thought we had when mine did that. But I can't imagine a circumstance where this could happen without a catastrophic failure. Chains can't just slip.

No clue what happened, but my 4WD still works just fine. I might pull apart the IWEs at some point to see what they look like, but I probably won't unless it gives me trouble.

 

is it e locker equipped? maybe going in and out at 18mph? had it on and didn't know it was on? or like others said must be traction control....

 

No way he was going 18mph. I have done burnouts while having mine locked in and unlocked it during one to get wheel speed up and have never had this happen.