Community Forums

outwestbound · 12-06-2015, 10:18 AM

Hi. Just wanted to get some advice on how to drive/ operate my (new to me) truck to avoid over revving the motor while in tow haul mode. My entire rig (truck + fifth wheel) is 28,000#. I drive in mountainous areas with 6-8% grades out west and in North Carolina. I recently tapped the breaks to late, I think, and the motor revved up to over 3,000 rpms briefly, which I don't want to repeat. I wont' try it, but it seems as if the diesel exhaust brake could blow an engine if used improperly, or maybe it has a fail safe before over revving the motor. If there is no fail safe, this would seem a design flaw.

I've since started approaching downhill road segments slowly so that the brake can kick in and hold me back as I descend. The error I appear to have made was getting up too much speed before engaging the brake, so it downshifted and ran up insane rpms. Also, there are times when I take it out of tow haul to disengage the brake because of high revving occurs in circumstances that seem inappropriate (not much of a grade at all - surprised me that the brake engaged). Sometimes the brake is annoying on rolling hills like in Kansas and I just turn it off.

Any basic advice on using this brake to avoid the risk of over revving the motor would be great.

Thanks

dwhit · 12-06-2015, 02:20 PM

I'm watching your thread. I have similar set-up that is new to me and I drive out west as well.

I've searched this subject on various boards. Most responses are to "allow the exhaust brake to do it's job" meaning don't interfere, and to begin the descent in a lower gear like 3rd. I have no experience yet with long grades but I surely will in summer. I expect I'll weigh less than you with a 42' three axle XLR.

My winter travel is FL which is pretty-much straight and level. Summer I'll be in Ouray, CO. Considerably more vertical. I converted from a 34' class A which was a harrowing experience going downhill towing another 5000lbs..

Randyman1 · 12-06-2015, 04:00 PM

I had a 2012 F350 with the 6-speed automatic that I used to pull a 39 foot fifth wheel with. As far as I know there is no exhaust brake your merely using the transmission and the back pressure of the engine when that downshift occurs, it's not very effective. I would take mine out of tow haul mode when I started down a steep grade to keep it from over revving so high and use the truck brakes and the trailer brakes to keep the speed down. Randy

Scottybdivin · 12-06-2015, 04:23 PM

2011 - 2013 or 2014 had what they called an "exhaust brake". In Tow/Haul mode, you were supposed to be able to tap the brake and as the transmission downshifted, the EGR would dump exhaust into the intake, therefore starving the engine. It was very ineffective and pretty much worthless. There is a Mike Rowe video on Youtube that illustrates how it works. Ram and GM used the variable vanes on the turbo for theirs and it was much more effective. Ford finally got it right in 2015. I had a 2013 DRW that I towed a 43' toy hauler and still have a 2013 F-250. No effective exhaust brake.

YosemiteBobR · 12-09-2015, 11:10 PM

So I have a 2015, and I still don't know how to effectively use it. It has no button as some do, supposedly it works with the tow/hull, but as I said it doesn't explain it very well. Can you?

Fred1609 · 12-09-2015, 11:37 PM

I have a 2011 F350. I tap the breaks as soon as I begin to travel down the hill not waiting until the last second to engage the "brake"....We live out West and have a ton of mountains and hills. The Tow Mode has worked well for me.

YosemiteBobR · 12-10-2015, 12:00 AM

Quote:

Originally Posted by Fred1609

I have a 2011 F350. I tap the breaks as soon as I begin to travel down the hill not waiting until the last second to engage the "brake"....We live out West and have a ton of mountains and hills. The Tow Mode has worked well for me.

Fred, all you do is tap the brake, while in tow/haul mode, right? I assume it will downshift by itself as the speed slows from the "exhaust break" and when it does this, does it stay in exhaust mode? I would like to know before I go experiment, I'll feel better when I put it to actual use

Tony Lee · 12-10-2015, 02:26 PM

Are you sure the engine is really over-revving. Most transmission control systems are designed to protect the drive train by immediately up-shifting automatically if engine revs get too high. Of course you lose a lot of braking when that happens and a runaway is inevitable unless you act quickly by heavy braking, but hey, the engine is protected. DPs do anyway.

2002dura · 12-10-2015, 11:14 PM

I have a 2012 and mine does a good job. I am grossing about the same as you and pull from TN into NC and down into SC all the time. Do Sams Gap, Saluda Mountain, Old Fort Mtn. and highway 25 going to Lake Hartwell by the Cliffs.

Don't worry about over revving the engine as it will not let you. The over rev limit is different for braking verses when you are on the go pedal. The 11's - 14's don't have the same turbo as the 15's on and uses back pressure to help slow along with the tranny grade braking. If you let yours get up over 3000 RPM's you will notice some additional "braking" along with the tranny. I usually hit around 3300-3400 RPM's coming down the mountains. 3rd gear will hold 50-55 MPH and 4th goes around 65 MPH.

Plan ahead and as you crest the mountain in tow/haul, tap the brake and it will downshift. Go ahead and get down to 4th. Personally 65 is to fast for me, so I go to 3rd and enjoy the ride down. Usually have to feather the gas to pick up some speed.

On the 15's up, the ones I have been in have a button to engage the exhaust brake. I do know with the exhaust brake on, even when not towing, it is more effective then mine. I haven't been in a cab/chassis so they could be different.

outwestbound · 12-11-2015, 05:28 AM

Quote:

Originally Posted by Tony Lee

Are you sure the engine is really over-revving. Most transmission control systems are designed to protect the drive train by immediately up-shifting automatically if engine revs get too high. Of course you lose a lot of braking when that happens and a runaway is inevitable unless you act quickly by heavy braking, but hey, the engine is protected. DPs do anyway.

I'll ask Ford about the automatic up-shifting. I don't think mine is doing that.

outwestbound · 12-11-2015, 05:33 AM

Quote:

Originally Posted by Fred1609

I have a 2011 F350. I tap the breaks as soon as I begin to travel down the hill not waiting until the last second to engage the "brake"....We live out West and have a ton of mountains and hills. The Tow Mode has worked well for me.

I think my issue is driver error. I let it get going too fast before engaging the brake out west in mountains, I think. In gentle rolling hills, where the brake "over reacts" while in cruise control, I'll just disengage tow haul. Without tow haul in rolling hills but with cruise control, the rig will just accelerate a little on the down hill segments, which is fine. Holding it back on the down hills segments in rolling gentle hills just burns fuel anyway.

outwestbound · 12-11-2015, 05:37 AM

Quote:

Originally Posted by 2007dura

I have a 2012 and mine does a good job. I am grossing about the same as you and pull from TN into NC and down into SC all the time. Do Sams Gap, Saluda Mountain, Old Fort Mtn. and highway 25 going to Lake Hartwell by the Cliffs.

Don't worry about over revving the engine as it will not let you. The over rev limit is different for braking verses when you are on the go pedal. The 11's - 14's don't have the same turbo as the 15's on and uses back pressure to help slow along with the tranny grade braking. If you let yours get up over 3000 RPM's you will notice some additional "braking" along with the tranny. I usually hit around 3300-3400 RPM's coming down the mountains. 3rd gear will hold 50-55 MPH and 4th goes around 65 MPH.

Plan ahead and as you crest the mountain in tow/haul, tap the brake and it will downshift. Go ahead and get down to 4th. Personally 65 is to fast for me, so I go to 3rd and enjoy the ride down. Usually have to feather the gas to pick up some speed.

On the 15's up, the ones I have been in have a button to engage the exhaust brake. I do know with the exhaust brake on, even when not towing, it is more effective then mine. I haven't been in a cab/chassis so they could be different.

Thanks. This makes sense.

outwestbound · 12-11-2015, 05:44 AM

Quote:

Originally Posted by 2007dura

I usually hit around 3300-3400 RPM's coming down the mountains. 3rd gear will hold 50-55 MPH and 4th goes around 65 MPH.

2007dura, relating the gearing to MPH is helpful. Do you use manual transmission mode often around NC? I only used it once I think on a two lane road climbing a mountain going back and forth on switch backs.

I know manual gearing control is provided for a reason, but I very rarely use it and wonder if this is a missed opportunity to operate the truck more efficiently.

What are the appropriate uses of manual with the + and - buttons?

Thanks

JohnBoyToo · 12-11-2015, 06:03 AM

With my new 2012 250 and 2013 350 towing an over 16k 5er I rarely used tow haul...Ford did the 6.7 right and the tranny is even better.

Since I didn't like the way it would downshift so quickly and kill momentum when in tow haul if I just lifted the throttle, unless I was in the open and using cruise, about the only time I would use the exhaust brake was when I wanted to stop.
I could use it and many times not use the foot brake because it would downshift itself when safe to do... I got to where I just punched the button when I wanted to stop and supplemented the engine brake with the foot brake as needed...
in MY two, the engine braking did FINE even bringing the combo down very quickly on one particular panic stop I vividly recall !

your rpm's sound ok, as stated befoer, it's smarter than you think about when to shift

Don't fret about it, just drive it and enjoy it... All I ever did to it was fuel and def every so often once I had them set up for towing heavy...

And as far as I know, the variable vane turbos WERE around before 2015.