2007 Z4 Coupe timing chain stretched at 71k

[Mr Tidy]

Sadly you do seem to have been very unlucky at that mileage - the E91 I saw advertised for spares or repair had done well over 100K.

I hope you get it sorted OK.

[Thrustyjust]

I wonder whether extended service periods creates issues with small items such as chains. The rollers on chains arent that big and any blackened oil, which has carbon in suspension , which is why it goes black could cause wear to increase over more regular oil changes. Just a thought.

[Z4M-2006]

I have changed 3 chains and guides on N52 engines.. One had done the guides but the other 2 had stretched chains giving timing errors.

Also changed a couple of heads due to noisy top ends,people initially think its the hydraulic lifters but its actually the machined barrel where the HVA sits (worn)...The machined fit of the HVA in the recess is imperative to maintain oil pressure,so when worn the oil pressure to HVA drops and makes the HVA "rattle"..

Well you learn something new every day. Does seem very rare though and still don’t understand why some cars suffer from it whilst the vast majority don’t????

You would have to think excess heat either thrashing to extreme ( trackday without proper prep) , thrashing on low / crap oil or just thrashing from cold .
Chain stretch is notorious in the 3.2 Vag V6 & affects some but not by any means all so suggests lack of mechanical sympathy / poor upkeep at some point of the engines life

It’s so random and hard to determine that I wouldn’t even hazard a guess

The most troubled by far is the 2.0, but there are millions of them engines out there

Some have broken at under 30k, yet I have seen not particularly well maintained vehicles run to 200k with no issue

If you wanted a guess I would say quality of components rather than any other external factor.

A majority of manufacturers are on chain drive , yet Bmw and VAG group really the ones that suffer badly with issues

[patriot66]

"If you wanted a guess I would say quality of components rather than any other external factor"...nail on the head
I used to work for a certain large BMW Dealer group and the vast majority of warranty issues were down to parts quality. The list was as long as your arm...Nikasil lined blocks, aluminium/black chrome window trim, recycled plastic trim parts, Slovenian made oil filters , wobbly Saint Gobain windscreens etc etc etc...ALL poor quality parts suppliers

[A4RON]

Thanks all

The engine light has disappeared again. Still holding out for the timing chain replacement in three weeks... Eeek