Scott:

Here’s a short version answer to your question – not the every detail answer:

Most “pickup trucks” can’t hold back a rig going down hill for extended distances.  (Some can - it depends)  The proper procedure is to keep your speed down and obviously the RPMs below the red line, but also to brake in short bursts.  Press the brake peddle firmly and quickly to reduce the speed 10-15 MPH.  Let the speed build back up – then quickly lower the speed with the brakes again 10-15 MPH.  Do NOT “ride” the brakes.  This technique allows the brakes to cool and be the most effective.

(You have a 2011 Ford and it has an exhaust brake but obviously it is not enough to hold your rig back.  There is no “on or off” with the Ford exhaust brake system.  It’s always on.  They 2011+ Chevy’s have an on / off for the exhaust brake but it is intergraded differently with the Allusion transmission so I guess GM wanted to give you that switch.  I don’t know about the Dodge having an on or off for the factory exhaust brake.  Just generic information)

This is an industry accepted braking technique to keep the brakes as cool as possible and the speed of the rig within a manageable RPM and safety range.

Hope this helps a bit.

Bill

The information that I can find on mountain ascents and descents is fairly general.  On the incline, keep RPM’s in the power curve, think that’s 1,800 to 2,200 rpm’s for the new Ford 6.7 “Scorpion” although  2,500 delivers a bit better for me.  OK fine.  Descend speed, no greater than the ascent.  OK fine.  But where should your RPM’s fall?  3%-4% grades no problem, 5%-6% mostly Ok, but when the descent is many miles, the 5^th wheel sure pushes you down the hill.  In long descents at 6%+ the weight of the trailer is greater than the gearing and engine brake can compensate if I attempt the same speed going down as going up the hill.  RPM’s go up!  I suppose 1st gear at 5 mph might work?  Where is the line for potential engine damage?  My engine redlines at 4,000 and for no factual reason anything approaching 3,500 is white knuckle territory for me.  It would be nice to have a rule of thumb for my “rig”, brake when rpm’s pass the 3,000 mark and brake down to 2,000 rpm and am hoping for some feedback and experiences.  Come on you “Grizzly Adams” Types!

travlingman wrote:

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Don't worry about over reving engine in grade braking, as it will not allow it too. The RPM's on my Ford are actually lower going downhill than they were on my last 2 Chevy's on the same grades at same speed.

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 If you will permit the observation, based on Howard’s posts and the data from his truck’s ECM (truck’s computer) I think he and the truck will disagree with this statement.  It can overspeed and you can damage the engine.  What is defined as an overspeed of an engine’s RPM’s are based on the specific engine.

The unloaded, i.e.  no power – like going downhill – overspeed (red line) on my 2006 Duramax was 4,800 RPM.  Loaded – i.e. under power - it was 3,200 RPM.  I don’t recall the numbers for the different Ford or Dodge engines.  I would expect they might be different as were the Detroit Diesel’s and Cat’s I used to drive.

It depends – but it is always good to stay below those “red line” numbers and not depend on the computer.

That said, on the 2011+ Duramax there is actually no “red line.”  However, GM reps have told me it is still the same as the 2006.  They just didn’t put a “red line” on the tack.  No, I don’t let it go to 4,800, but that is the unloaded number.  Going downhill I like to stay around 4,000 or below, but that is a personal limitation, not one the engine demands.

“Your mileage may vary.”

Bill

Since you guys are on the subject of ascent/descent, please forgive me for asking this question, but I'm blonde, O.K.?  We are not yet fulltiming, but I will be well-prepared when the time comes as I study more about RVing than a rocket scientist studies, well, rocket science!  One of my biggest concerns are the ascents/descents.  (I do plan to do some of the driving for obvious reasons.)  Here's my question... do you guys travel any road, or do you avoid those highways and byways where the ascent/descent is steep?  Do you refer to and use reference material such as the Mountain Directory to avoid those roads?  Or, are these white knuckle roads UNavoidable and I'm just too naive to think these highways/biways can be avoided?  Your comments sound kinda scary to me!

Thank you, in advance, for your input!!

Mary Sunshine wrote:

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Here's my question... do you guys travel any road, or do you avoid those highways and byways where the ascent/descent is steep?  Do you refer to and use reference material such as the Mountain Directory to avoid those roads?  Or, are these white knuckle roads UNavoidable and I'm just too naive to think these highways/biways can be avoided?  Your comments sound kinda scary to me!

Thank you, in advance, for your input!!

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I agree with Gene’s comments, it does depend on the rig.  We do use the Mountain Directory for information – a good choice IMO.  I will avoid narrow roads with switch backs more than I will avoid grades.  If I can avoid a long grade then usually will if all things are equal.  Most of the time they are not.  But we have never not gone where we wanted to go because of a long steep grade as such.  This includes the US and Canada.

As Gene says, it depends on your rig and your own driving ability / experience; this includes your knowledge of the capability of your equipment and your comfort factor.  Both are equally important.  I have never had “white knuckles” because I don’t create a situation where they will occur "for me."  They might for others on the same road with perhaps a different rig.  It depends.

My perspective

Bill

When we hit the road I was very worried about hills, not going up (the easy part), the coming down (the hard part).  Now that I've driven a few hills I've learned how best to control my vehicle.  I slow down at the top and get my transmission into 3rd gear BEFORE starting down the hill.  So far I have not encountered a hill that required more than 2 brake sessions while desending.  But if I saw this sign I would be looking for an alternate route :)

Oh my, NorCal.  That pic takes my breath away just sitting here comfortably on my sofa!  Geez how in the heck does one back up when a sign such as this appears?

Making sense of it all, I think.  If, in my life, I have ever dissed an engineer, please forgive me.  I have driven the Sierras and Rockies for many years, that is in my backpacking years.  I would usually have to select my gear to make it up the hill or to control the descent.  These TV's are engineered to manage this and are quite efficient, dah!  53Merc said it great, and I guess because the only hill I've towed is near Kerrville, TX, 6%, 3 miles or so, and straight, it didn't register.  I crest the hill at 55 or so, start down, brake, and the truck would do it's thing and maintain speed down the hill.  Next time we head to hill country, I've already told Fran that there may be a few practices "go arounds" at various speeds up/down to see how the truck handles it.  I also spent some time in the TheDieselStop.com forum and gaind some "Scorpion" insights.  Then I think another light bulb went off, weights.  It all works best if you stay within the weight limits, another dah!  I would guess that the closer the rig gets to the GCWR, the closer you are to the limits of the equipment, including RPM limits!

But, NorCal Dan's 26% grade may just be the exception,

53 Merc wrote:

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Mary, I figure if the road is paved, we can do it, within reasonable constraints. You just have to be aware of your and your truck's limitations. The road between Minturn, CO and Leadville just happens to be the best route to our daughter's house. Lots of switchbacks, but with due caution and patience it is a cinch. And, we are heavy, especially for an F250 (weight police warning, I know it). Our fifth wheel weighs in at about 14,500.

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53 Merc if you have ideas of visiting your daughter anytime soon you may have to take a detour.  Hwy 24 is closed at Tennessee Pass because of the cave-in of an old railroad tunnel.  We had to take Rte. 91 out of Leadville to get to I-70.  It wasn't all that bad until the final descent to I-70 where we underestimated the steepness.  The brakes started to feel "funny" so we thought that would be a good time to pull off and have lunch! After a 30 minute break the brakes were cooled down sufficiently and we made it the last 4 miles without issue.

Bill and Linda wrote:

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travlingman wrote:

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Don't worry about over reving engine in grade braking, as it will not allow it too. The RPM's on my Ford are actually lower going downhill than they were on my last 2 Chevy's on the same grades at same speed.

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 If you will permit the observation, based on Howard’s posts and the data from his truck’s ECM (truck’s computer) I think he and the truck will disagree with this statement.  It can overspeed and you can damage the engine.  What is defined as an overspeed of an engine’s RPM’s are based on the specific engine.

 

The unloaded, i.e.  no power – like going downhill – overspeed (red line) on my 2006 Duramax was 4,800 RPM.  Loaded – i.e. under power - it was 3,200 RPM.  I don’t recall the numbers for the different Ford or Dodge engines.  I would expect they might be different as were the Detroit Diesel’s and Cat’s I used to drive.

 

It depends – but it is always good to stay below those “red line” numbers and not depend on the computer.

 

That said, on the 2011+ Duramax there is actually no “red line.”  However, GM reps have told me it is still the same as the 2006.  They just didn’t put a “red line” on the tack.  No, I don’t let it go to 4,800, but that is the unloaded number.  Going downhill I like to stay around 4,000 or below, but that is a personal limitation, not one the engine demands.

 

“Your mileage may vary.”

 

Bill

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 According to the op's post, he said approaching 3500 RPM he gets worried, his red line is 4000, so when did the engine go into red line territory? The computer linking engine and tranny will cause a shift to a higher gear to drop RPM's if it gets into a situation that will damage the engine. My 02 and 07 Chevy's did the same thing, even had the 07 force an upshift because RPM's got to high. I guess we just disagree on trusting a computer to do what it is suppose to do for your truck if it gets into a situation that requires it to act.

travlingman wrote:

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Bill and Linda wrote:

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I must be missing something as I see no post in this thread where "Howard" talks about his engine being trashed because it over revved during grade braking.

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 Howard is the host and owner, along with his wife, Linda, of this forum.  A few days ago he had his 6.0L Ford engine go out and according to his reports, it was from an over speed going down hill using the engine for braking.

Welcome to the Forum, but being new you probably didn't know all the posts and information he provided.  This thread is a an outgrowth of that discussion and his posts on his blog.

Bill

travlingman wrote:

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Bill and Linda wrote:

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travlingman wrote:

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Don't worry about over reving engine in grade braking, as it will not allow it too. The RPM's on my Ford are actually lower going downhill than they were on my last 2 Chevy's on the same grades at same speed.

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 If you will permit the observation, based on Howard’s posts and the data from his truck’s ECM (truck’s computer) I think he and the truck will disagree with this statement.  It can overspeed and you can damage the engine.  What is defined as an overspeed of an engine’s RPM’s are based on the specific engine.

 

The unloaded, i.e.  no power – like going downhill – overspeed (red line) on my 2006 Duramax was 4,800 RPM.  Loaded – i.e. under power - it was 3,200 RPM.  I don’t recall the numbers for the different Ford or Dodge engines.  I would expect they might be different as were the Detroit Diesel’s and Cat’s I used to drive.

 

It depends – but it is always good to stay below those “red line” numbers and not depend on the computer.

 

That said, on the 2011+ Duramax there is actually no “red line.”  However, GM reps have told me it is still the same as the 2006.  They just didn’t put a “red line” on the tack.  No, I don’t let it go to 4,800, but that is the unloaded number.  Going downhill I like to stay around 4,000 or below, but that is a personal limitation, not one the engine demands.

 

“Your mileage may vary.”

 

Bill

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 According to the op's post, he said approaching 3500 RPM he gets worried, his red line is 4000, so when did the engine go into red line territory? The computer linking engine and tranny will cause a shift to a higher gear to drop RPM's if it gets into a situation that will damage the engine. My 02 and 07 Chevy's did the same thing, even had the 07 force an upshift because RPM's got to high. I guess we just disagree on trusting a computer to do what it is suppose to do for your truck if it gets into a situation that requires it to act.

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I think you misunderstand my point.  I do “trust” the computer in truck as such – I don’t try to override it.  However, Howard’s “computer” obviously is one example of the fact that they can fail – or perhaps the engine wasn’t capable of doing what the computer was told it could do by design.  We don’t know but the engine is trashed regardless.  But Howard stated (not the OP) his engine computer reported an “engine over speed” and that damaged the engine.  So it is clear something went wrong during an engine the over speed condition that the computer apparently allowed according to the computer’s engine log.

When I flew aircraft one of our key training items was to always try to stay below the red line and “keep it below the yellow line if at all possible.”  That was a very good way to keep a safe margin.  That’s what I do with my truck engine.  I’ve seen the Duramax go to well above 4,000 RPM during hill braking and at 100,000 miles it was still going strong without one repair.  As the OP noted, his Ford red line is 4,000, the Chevy is 4,800 – unloaded – i.e. braking, not pulling as you know.  Duramax’s are different as you noted.  But in response to the OP, IMO it is a good idea not to use every bit of the capacity designed in to an engine / transmission unless you have to.

I also agree with Lindy, I wish GM had left the red line on the tach.  I know why they took it off, but I disagree and continue to use the former tach red lines as reference points to try and stay below while still “trusting” the computer.  That’s just good “piloting.”

All that said, using proper braking techniques, along with enginer / exhaust braking, will enable the best overall control of the rig and most likely increase the likelihood of not damaging engines or transmissions that may or may not be capable of their published specifications due to age or simply design in difficult conditions.

My 2 cents

Bill

Bill and Linda wrote:

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.  However, Howard’s “computer” obviously is one example of the fact that they can fail – or perhaps the engine wasn’t capable of doing what the computer was told it could do by design.  We don’t know but the engine is trashed regardless.  But Howard stated (not the OP) his engine computer reported an “engine over speed” and that damaged the engine.  So it is clear something went wrong during an engine the over speed condition that the computer apparently allowed according to the computer’s engine log.

 

When I flew aircraft one of our key training items was to always try to stay below the red line and “keep it below the yellow line if at all possible.”  That was a very good way to keep a safe margin.  That’s what I do with my truck engine.  I’ve seen the Duramax go to well above 4,000 RPM during hill braking and at 100,000 miles it was still going strong without one repair.  As the OP noted, his Ford red line is 4,000, the Chevy is 4,800 – unloaded – i.e. braking, not pulling as you know.  Duramax’s are different as you noted.  But in response to the OP, IMO it is a good idea not to use every bit of the capacity designed in to an engine / transmission unless you have to.

 

I also agree with Lindy, I wish GM had left the red line on the tach.  I know why they took it off, but I disagree and continue to use the former tach red lines as reference points to try and stay below while still “trusting” the computer.  That’s just good “piloting.”

 

All that said, using proper braking techniques, along with enginer / exhaust braking, will enable the best overall control of the rig and most likely increase the likelihood of not damaging engines or transmissions that may or may not be capable of their published specifications due to age or simply design in difficult conditions.

 

My 2 cents

 

Bill

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I must be missing something as I see no post in this thread where "Howard" talks about his engine being trashed because it over revved during grade braking.