The gross combined weight rating, that's truck and trailer, is 20,000, with a maximum fifth wheel trailer weight rating of 13,600 (2WD) or 13,100 (4WD). Those numbers are directly from Ford. Even an F550 would be underrated for the weight your truck sees.

 

If you are just going to dismiss my educated suggestions on what to check without even looking I'll stop thinking of ways that this problem could occur.

 

I've seen first hand, more than once, brakes hanging up(sticking) without having the whoa pedal applied
Is that what you were referring to?

 

You are way over what Ford says your truck can or should tow. That's a fact. You can explain it or justify what you're doing however you like, but you are towing too much weight for either truck. If you are involved in an accident, you can be cited or found at fault for towing over capacity.

Is that actually a good enough reason for you not to do something?

One of the first things that pretty much everyone learns about towing is that while being able to get a load moving is nice, being able to control it and stop is much more important. That's why trucks have different towing capacities. You can't tow a 5th wheel with a ranger, even if you swap in a 460 drivetrain. Did you really not know this? Do you actually believe that the only difference between an F-350 and an F-550 is that the F-550 "may have different tires and wheels"?

The gauge on the dash only reflects engine coolant temperature. The fact that the transmission cooler lines go to the radiator is good, but you need to understand that the transmission temperature can still be very different from the coolant temperature. I'm shocked that you need this explained to you, to be honest. I'll just stop here before I offend further.

 

No, not quite. I think there is a wiring issue with the trailer causing the PCM to think the brakes are on. This will keep the torque converter from locking, causing the exact symptoms he's seen on BOTH trucks. I don't think the brakes are actually on, I think the computer THINKS the brakes are on.

 

Might be worth getting a trans gauge in there to actaully see what your temps are at. If you are running the stock 7.3 cooler a 6.0 cooler is a fantastic upgrade.

Regarding the weight towed, yeah its over what the truck is rated for, but it will do it all day long. Its a weekly routine for mine as well and I have never had issue, but run a manual. If you continue towing with either truck I would highly suggest dropping in a larger or more efficient cooler and a valve body. 22k is no joke for a 7.3, but it will do it all day long without issue. Stopping has always been my #1 concern.

GVW is trailer+ truck to not to exceed 24k... which no one follows, but keep in mind the DOT zealots can pop you if they want...

Curious to see if either truck recovers after they cooled down. I agree with mark on the PCM/brake issue, considering you know have a shutter in the trans since the issue. Has it gone away?

 

How would the PCM 'lock' or 'unlock' the converter? Would this happen at all speeds? And would it 'unlock' if it thought the vehicle brakes were on? How could I check if this was happening?

 

Gotcha. That makes sense and thanks for clarifying.

 

They could put almost everybody on the road in jail if they checked recommended GVWs. The Kenworth tractor that pulled the 140,000lb bridge beam into town last week probably had a 73,000 GVW. All that extra weight is supported on trailers and dollies.
My mystification is mostly due to why - right now - I am burning up transmissions with a much lighter load than I have pulled in the past (I have about 9000lb on the trailer now). Someone posted that the PCM might be getting a brake light on signal through the trailer harness and it 'unlocks' the converter - which makes a lot of heat. This could make sense as if there is something wrong in the trailer wiring it could affect both trucks. The electric brakes and brake controllers do seem to work fine on both trucks. How would I check if this signal is getting to the PCM?
I suppose the only way I can check if the 7.3's tranny is bad is to drain and replace the fluid and see how it works. It doesn't look great on the dipstick.
I would love to have manual transmissions and not have to have all of this trouble. Seems very sad that currently there is no option for a manual transmission for a new truck.

 

It's possible a wiring problem would show on a scan tool by monitoring the BPA (brake pressure applied) and BOO (brake on/off) PIDs , but I'm not certain. Maybe Mark knows the answer.

 

It's really easy to see if the torque converter is locked or not. Warm the trans up because the converter won't lock when the fluid is cold. It usually doesn't take very long, especially at this time of year. Even when temps are near freezing it only takes a few minutes of driving.

Get it into overdrive, and step on the pedal a little, enough to rev the engine up but not downshift into 3rd. If the RPMs don't change with the speed, the converter is locked. If the RPMs increase by a few hundred while the speed remains mostly unchanged, the converter is unlocked.

If you're in overdrive, on the throttle, in a warm truck, the converter should never be unlocked.

Also, you're crazy for not having a tranny temp gauge in BOTH trucks.

 

F450's and 550's have a much bigger brake package, hence the increased towing capacity. If you are towing a 16,000lb tractor with a truck that is rated to tow 12,600lbs (which I believe the 2001 F350 is rated at, either way, it wasn't rated any where near 16,000 plus the trailer), you are asking the brakes to do way more than they were designed to do. Yes the transmission and engine can handle it but to safely be able to stop is the questionable part.

 

With properly working trailer breaks, my truck does very little braking use

 

#1 Reason for Death by Heart attack.....Older men Hauling their overweight selves around, and Their Pumps and transmissions give out......Just sayin.

 

Of course you must have trailer brakes on any trailer over 3000lbs. You're only asking the truck brakes to stop the truck itself. The brakes on my tandem dually trailer are so good I sometimes use them alone for braking or descending hills - must be a throwback to my over-the-road trucking days when you often used just the trailer brakes (someone else maintained the brakes on trailers).