Engine Break Problem?

Perhaps it is your engine brake!?. You may have a pedal switch not working properly or your dash switch may not be working.

 

If it's a paccar the air compressor sounds a lot like a engine brake while pumping

 

Depending on what truck your driving, engine, transmission and owner programming, it could be the engine brake engaging. Probably was. Depending on mode setting, switch settings, gear selection and sensor inputs, the engine brake can engage, disengage, transmission upshift and down shift, apply the air brakes and change throttle settings very disconcertingly. It's very spooky if you came from a truck that did none of those tricks. If you have not done so already, I recommend you find the owners manual and read up on what your truck can do so when it does something different than planned you understand what and why! Learn those settings and what they do. The 1st time I got in a new Freightliner Cascadia Evolution with the Detroit engine and automatic transmission, it was so different from what I had driven before, it took a bit of time to figure out the dash and controls. Then it promptly scared the lunch out of me and stopped dead when I was half way out onto the road. After what seemed like a forever delay it decided what gear it wanted and started to move again. Turns out it would do that trick on a regular basis. Especially in low speed parking and maneuvering situations. They wanted me to go grab a hot load and scram. I told them no and I was going to take some time and figure out how to safely operate that truck. I did not want any more total surprises out in traffic. I found a bunch of them. I spent a chunk of time feeling that truck out and reading the book. I got a lot more surprises over the next week as it revealed more of its computerized tricks. And it was common for it to do things differently than I expected or often wanted. It makes for an interesting winter evening at gross weight on a remote, curvy and hilly mountain highway when your planning to slow down for the next corner and release the throttle expecting the engine brake to slow you down but instead it chooses to deactivate the engine brake, shift into neutral drop the engine to idle and go into ECON mode and coast out of gear while going down hill. If you do not expect it, automatic freewheeling will get your attention! I found with that truck, I had to greatly expand my all safety gaps in all directions because of its predictable unpredictability. Especially when entering traffic from a side road. But I am retired now so It's no longer my problem.

 

I really appreciated the posts, especially this one from Americanrambler.

Comparing our experience with Autos to this last post, you make me worried abou the Autos now. Actually scared to think about it. Did none of you think to put the #### auto into a Manual mode (A large M on the paddle or similar) and keep it there in a downgrade with the jake going all the way down.?

 

And I thought it was all rookie driving. haha
Now, I like my manual so much more.

 

What are you running? DD15? With a Dt12?

 

It was the DD 15. I thought it was a great engine trapped behind a really tight electronic power governor. Every now and then under just the right combination of conditions it would seem like the engine responsiveness would jump to a whole much higher level then almost immediately you could feel the power being pulled back.

Another clue I got about that was I was through a terminal and talking to some shop guys. They had a batch of new Cascadia Evoloutions with automatics come through that were snapping rear ends out from under them. They had some kind of geared turbos in them. The factory service reps and engineers come out to try and figure out what was going on. It turned out there was a flaw in the engine software that controlled the power settings. The actual torque being delivered at 1100 rpm was way over spec. They fixed the software and the problems went away.