Engine Brake Weak

As I understand the Gen 5 DD15 activates the rear solenoid for low engine braking, both front and rear solenoids for medium braking and for high braking both front and rear solenoids are activated along with EGR . Each solenoid controls 3 cylinders. It sounds like you are not getting any contribution from the rear cylinders. Can you post the last six of your VIN and did you get a description of what was done at dealership to make the determination. Seeing technician notes would be interesting, if done without naming location. I am seeing about 28 steps in troubleshooting for poor engine brake performance.

 

Does your company have more than one of these 2023 Cascadia's with the same spec's? It would be nice to compare your truck with another on the same grade and load. I sure other driver's in your company come down same hills. The Gen5 DD15 has a 21 to 1 compression ratio which is higher that earlier versions, Which in my thinking should give slightly better engine braking. If you got engine faults related trouble shoot them first otherwise going through the diagnostic steps for poor engine brake performance is what I would recommend. I am certain that Detroit Diesel will be able give some guidance to dealer if they have need help solving problem. Here's the diagnostic steps for poor engine brake performance.

 

you need to take off exhaust rocker arm and look for stuck actuator pistons...
happens very often with all dd15 models.

 

I had that problem myself, but he said his is a brand new engine. I would be shocked (and pretty mad) if I had that problem on a new engine.

BTW you don't actually have to take the rocker assembly off just to check the pins. You should be able to use an air chuck with a rubber tip in the solenoid orifice. The pins will pop out from air pressure too. The diagnostic procedure calls for 50 PSI.

 

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