Quote:
Originally Posted by Vanne
Any idea about root cause? Like previously mentioned Ive never seen one go like that. Did the chain linkage sheer? Or was it something else? Keen to find out more. Again, sad to hear about this mate.
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Vanne - I wish I had more answers to share. My original plan was going to start with pulling the valve cover and vanos to validate that the upper timing chain guide is still intact (replaced with the Beisan chain guide 3 years ago) and to check that the two exhaust cam hub tabs are also intact (upgraded the oil pump disk to the Beisan drilled one 3 years ago as well).
I didn't end up having the shop dig into the motor, as once they eyeballed the failure and we covered the likely rebuild options/costs (bent valves, likely damaged pistons, mandatory new oil cooler, etc.). It just didn't seem worth the labor cost to ask them to try and answer the "why did it fail" question.
At this point, with the car back in my garage, I'm not motivated to spend the time digging (even at $0/hr)... I'd rather spend time sorting out my next/replacement Z4MR. I'm confident in the maintenance that I did to the car over the five years I had it, and the codes I chased for the few months before the failure pointed to either bad sensors (cams or crank), dirty/stuck vanos solenoids, or a stretched timing chain... the intermittent nature of the rough idle and codes being thrown was just such a head scratcher!
Occam's razor: I'm resigning myself to the fact that this was an incredibly uncommon failure, which I believe was either caused by some error made by me in retiming the engine multiple times during this troubleshooting, or by a stretched timing chain.