Anyone Else Experience This? (Why my engine died)

[LeiseyJr]

So found out why my engine catastrophically failed. So a year ago, the guide failed I assumed it was poorly manufactured guide even though BMW, and it failed. I don't know how long it was like that noticed it when adjusting valves. Replaced and it and put it all back together.
Hint #1 by samleisey, on Flickr

Fast forward 1 year later, and same issue. Except this time when it broke was a catastrophic, as broken piece fell into timing chain and knocked chain off crank sprockets.
Neat by samleisey, on Flickr
Neat by samleisey, on Flickr

Teeth by samleisey, on Flickr

Just like my dogleg, broke some teeth. The single chain still hasn't completely snapped so maybe BMW does know what they're doing and single chain is plenty strong. I'm amazed it didn't break.

So what my father and I worked out, is the guides both failing its not a fluke. From presumably too much pressure. The pistons for the tensioner has been sticking this whole damn time. So presumably its been failing to dampen, and the guide has been getting hammered. I'm pretty sure it was the timing cover that must be damaged, when we got this engine at 191K it had no timing guides. So all of it was replaced and I believe tensioner piston was, only thing that's the same is the cover.

[Ju@n]

I haven't seen that. If your hypothesis is correct, then swap the tensioner spring assembly. When I did the timing chain "service" I changed everything apart from the sprokets. Including guides/chain/tensioner.

[athayer187]

Yikes.

The tensioner piston should move up and down (in and out) with little resistance when you remove the top plug and drain the oil - it should be smooth.