2018 6.4 Towing

[Vern Losh]

I have a 2018 2500 with 6.4 and 4:11 rear end. I tow a 30' travel trailer at about 8,000 pounds.
Going on downhill grades the engine will at times jump up to a little over 5,000 rpm's. I try to use the accelerator a bit to get it to jump back into a different gear to drop the RPM's.

Any other suggestions for the downhill grades and RPM's with the 6.4 engine/

Thanks in advance, Vern

 

[jvbuttex]

I have a CTD in my 2018 2500. I noticed this also in my 2015 1500... when going down hill, if you are building speed w/o the use of the accelerator, the truck recognizes this and will slow you down by down shifting... keeps you from building too much speed going down hill. I cant say it will jump to 5k, but I have a ctd, so your 5k might be more like my 25-3k rpm.

 

[jvbuttex]

I do find at times i will press on the throttle to get the truck to down shift if i see its safe to build a little speed, like when your coming down in a valley and heading backup the other side.

 

[crash68]

@Vern Losh are you using the Tow/Haul mode? Also is the truck slowing down? Or picking up speed after the truck downshifts(rpm rise)?

 

[mtofell]

Be sure tow/haul is on, manually adjust gears. I've seen 5K a few times while grade braking with my setup (11K 5th wheel behind the same truck). Overall, for a gas engine the grade braking is pretty good in most cases. Of course, I need to use the brakes sometimes but not often or hard enough to overheat or damage them.

 

[ramffml]

I have a 2018 2500 with 6.4 and 4:11 rear end. I tow a 30' travel trailer at about 8,000 pounds.
Going on downhill grades the engine will at times jump up to a little over 5,000 rpm's. I try to use the accelerator a bit to get it to jump back into a different gear to drop the RPM's.

Any other suggestions for the downhill grades and RPM's with the 6.4 engine/

Thanks in advance, Vern

These gas engines also have "engine braking", the transmission will downshift and also cut gas when it detects you are trying to slow down on a hill. This is a feature designed to help with braking.

But 5000 does sound quite high. My 5.7 doesn't rev that high that I'm aware of.

 

[dhay13]

This is normal functioning. The trans will downshift to help keep speeds down. IIRC it is active when in tow/haul mode but I might be wrong. I can go down a 6% extended grade towing my 9000lb boat and never touch the brakes. 5000 RPM's does seem high but yes, it will rev higher as it downshifts

 

[2003F350]

While 5k is higher than I'd want to run for extended periods, redline on a 6.4 is listed as 6400 RPM. So you shouldn't be hurting the engine spinning those speeds.

Otherwise, I echo everyone above. I've had my Wagon do this pulling our 7k camper, there is a hill in the northern part of the state that I'm pretty sure is a half mile at something pushing 10 degrees...it's STEEP and LONG. Went up the hill going to the campground and didn't really have any issues, held about 45 mph because I started at the bottom at about 50. Headed home, the Wagon downshifted and shot to 4500 RPM and kept trying to climb as it tried to keep the truck at a manageable speed (we started at 55 at the top and were doing 70 at the bottom and I never touched the gas...did press the brake a few times).

 

[HEMIMANN]

Interesting. I tow 7,000 lbs with same rig and 3.73 axle, never had a downshift to that high an rpm going down steep hills in tow mode. I also use tow mode when towing, so can't say what it would do without it.

 

[2003F350]

Interesting. I tow 7,000 lbs with same rig and 3.73 axle, never had a downshift to that high an rpm going down steep hills in tow mode. I also use tow mode when towing, so can't say what it would do without it.

The hill I referenced is the ONLY hill I've pulled on that has that steep of a grade for that amount of distance. Part of why I've seen RPMs that high on that hill is because the road is marked 55 mph, so the truck is trying HARD to keep that speed. If I were trying to hold 65 it probably wouldn't do it, wind resistance would do most of the work.

 

[62Blazer]

As said above this is a normal function when in the tow/haul mode as the trans will downshift in an effort to control speed, and thus this causes the engine rpm to increase. 5,000 rpm is not a concern especially under these conditions as there is very little load on the engine. Cruising downhill and basically supplying no fuel to the engine is putting very little stress on the engine as it's basically just friction resistance, definitely nowhere the stress the engine would see if you were climbing a steep hill with your foot on the floor and spinning 5,000 rpm as the engine was trying to make enough power to keep going.

 

[CMV157]

Agreed with others, mine does this sometimes and it's probably fine. I personally don't like it and would rather use a tad more brake than to scream over 5k. To avoid this from happening, turn tow/haul OFF and use manual shift mode. It will only downshift as far as you select it at that point (while coasting downhill).

 

[Willie Mosher]

I have the same truck an tow a 5000 lbs camp trailer.
I live in southwest we have few hill
here -288 feet to 11000 feet.
An see temperatures as well.
The 6.4 gas engine like 4000 RPM
Gone up any hill . it max torque is about 4200 and takes a little getting used of running this fast.
Allway used tow/hall let truck do it
Job it was engineer to do.
Not used the tow/hall will save you
Very little gas .maybe you costs a transmission and big break job.
Gone Down hill set the Cruise control
For 5 to 10 mph slow you like to go.
Have fun an go safe. Willie.

 

[Ratman6161]

Everything is functioning the way its supposed to. This is a safety feature and keeps your brakes from over heating. I vave towed a travel trailer over Wolf Creek Pass in Colorado (with a different truck but same idea. Going down the west bound side towards Durango, it's 7% grade with switch backs and 30 MPH curves. I thought I was barely using the brakes. But...there was a pull off after the steepest part so I pulled in to check my brakes. Even though they didn't feel like they were fading, the brakes on both the truck and the trailer were so hot I literally burned my fingers touching them. So yes, just let the grade shifting work like it's designed. Relying on your brakes in this scenario they will over heat a lot more and a lot faster than you might expect. If you want your engine to run at a lower RPM, then go slower, though in my example I was only going 25 MPH.

 

[Wingnutt]

Let the computers do their thing. They won't allow the engine to hurt itself.