Yes, I would slow her down so that your not dropping to 2nd gear....3rds ok, but again reduce speed going down grades.
5* has a cool feature when in tow/haul mode that helps the truck engine break optimally.

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4500 is def a little high (sound wise anyway). These engines don't have the greatest compression braking for sure, but I also use the brakes to help.

 

For me, I hate the T/H downhill downshifting programming... I know how to manage my brakes and speed... I lock out gears manually to use the engine AND the brakes so that I'm not relying on just one of those to control my speed..

I even hate the CC downshifting when the downhill speed goes more than 5 mph over the set speed when I'm not towing anything...

Again, this is just the way I like to drive/tow that works for me.. I also only go over passes here in WA State, so nothing more than 6% for the most part. It's not like I'm doing that Ike Gauntlet thing on every trip..

I see folks towing or driving class A's that have their brake lights on the whole way down a grade.. Scares the hell out of me.. I hang back and just hope they don't lose their brakes!! I tap my brakes as needed and use the engine as well to balance out the two.

Good luck!

Mitch

 

Every time I get on I-80 and head down from park city to salt lake city(~3000ft) I see everything from empty VW Jettas to loaded down Semis leaving trails of smoke billowing out of their brakes. Its incredible.

My trucks engine braking leaves a bit to be desired on the steeps, even empty. I agree that getting below 3rd seems to make the engine angry.

I was actually reading an article that the peak stress a WELL TUNED engine sees is actually on the intake and exhaust strokes at high rpm. During the power stroke, the force of the explosion is working against the tension created as the piston and rod are accelerated from TDC down the stroke so the net total force is actually less. Only when your engine starts pinging and detonating before TDC while the piston is not ready to fall back down do you run into huge loads. I would imagine in an engine braking scenario there is little to no explosion so every stroke is under full tension and compression from the piston weight and high rpms. Getting the RPM's too high is probably not a great idea.

 

I can't say for sure but I've heard having the jake brake on turns on the brake lights for the diesel pusher motorhomes?