Quote:
Originally Posted by petrel
On the Saturday morning of my weekend journey I had an unsettling thing happen with my Freightliner. When I approached the first traffic light of the day on a 55mph road, the engine brake almost stalled the truck, instead of just letting go once the truck was sufficiently decelerated.
Needless to say I was bewildered and thought it was a fluke, until it did it again at the next light. Still in denial, I guess, I just switched the engine brake off and back onto high.
At the third light, just about when the brake was about to stall the engine, the engine fought back and gave itself a little throttle! It took both feet planted firmly on the service brake to hold the rig while the engine and the brake fought it out and I reached for the brake switch.
Fortunately, the brake gave up and let go of the engine before I could reach the switch!
I switched off the engine brake and drove without it for the remainder of my Saturday journey.
After a protracted period of internet research, I resorted to digging out the Freightliner manual, where I found this (in bold print):
WARNING
...If the engine
brake is engaged when the transmission is
in neutral, the braking power of the engine brake
can stall the engine, which could result in loss of
vehicle control, possibly causing personal injury
and property damage.
I must have switched it on along with the headlights and cruise control or something...what a dummy!
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If you read what you wrote (in red) and think about it a little further (if you had to step on the brake with both feet to keep it stopped the transmission was not in neutral, it was in gear and the clutch was engaged, lugging the engine down)you will see that it was not the engine brake trying to stall the engine it was the transmission, more correctly the clutch, not releasing at close to a stop, causing the engine to lug almost to the point of stalling. The transmission ECM may have been having a bad day-my 12speed Freedomline has an occasional,rare, questionable action that usually corrects itself, or once in a blue moon requires a power off reset. You flipping the engine brake switch was purely coincidental.
Your truck chassis is pretty much identical to mine only a year older
Any computer controlled engine, when running properly, will NOT stall the engine with the engine/jake/exhaust brake switch turned on. There are settings in the ECM that control when and how the engine brake comes on/off etc. The only time I have seen the engine brake stall an engine is if you are decelerating hard (on the service brakes) while downshifting at the same time and miss a shift or if the engine is mechanically controlled.
As an aside Detroit Diesel uses an actual Jacobs Engine Brake system.