[avocet]

On my X5d I was cruising on highway at maybe 75mph with a trailer with 2 motorcycles in it(maybe 3500lbs) when my trans jammed into second and my revs hit the stop past redline. Trans wouldn't shift or go into neutral. I got over to the side of the road but rpms were in the red for quite some time. I had the gear icon in dash, and it stayed on with it in 2nd until I came to a stop and shut down.
I restarted and the light was gone, and it shifted into drive normally. I crept to the nearest offramp(maybe an 1/8 mile) and as I got off the highway my engine began to tick.
I stopped and checked codes with Carly. No trans codes, but had 459b Smooth running controller cyl. 5 and 4595 smooth running controller cyl. 6 engine codes. I thought maybe it was injectors and nursed it into a nearby parking lot since there was no real safe place to remain stopped.
The ticking was consistent with rpm, and even would subside and almost go a way for a minute at a time. She was a little rough on idle and felt low on power. The parking lot I was in was a reserved lot, and the owners asked I do not park there. I had called AAA and a tow was coming, but I had to cross the lot so the delivery trucks could access the building.
When I went to restart and cross the lot, all hell broke loose. Major knock and clucking and ran like crap. Like major knock. I shut down and waited for tow to the nearest euro mech. shop. The shop owner was able to come over and tow my trailer to his lot, and I got my X5 towed there.

Long story short, it really seems like my engine to toast. Over rev to structural internal failure seems likely consider the rev counter was pegged on the high end for awhile.

Now, the question is, WTF caused this? I am at 197,000km (~130000 miles), so not a very high mileage vehicle, and have been running an xHP stg 3, no drag race mode, no launch control and no line pressure bump. Full deletes with JR2.8. Vehicle is driven fast but not crazy hard. Fluids and filters recent.

Do I put in a new engine and risk exploding it if the trans does what it did again?
Anyone with any insight on WTF happened?

[Nadir Point]

https://en.wikipedia.org/wiki/Diesel_engine_runaway How's ur CCV setup?

[lnxguy]

He's not going to get a runaway from anything coming out the CCV. Only time a runaway happens is when a turbo lets go and he'll absolutely know what's happening.

I wouldn't put a new/used engine in until you figure out what's going on with the transmission.