2007 Z4 Coupe timing chain stretched at 71k

[A4RON]

Hi all,

Back in Feb I had an intermittant engine light that would come on for a day or two, then disappear for a few weeks, before coming back on again briefly and disappearing etc. I thought it might have been a sensor playing up with heavy rainfall.

It didn't appear again until last month, when it stayed on constantly for about a week just in time for it's annual service. My trusty European indy carried out a diagnosis and said it's the timing chain that's stretched and will need replacing at NZ$2k / 900 quid - including parts and 12 hours labour.

My car has just ticked 71k miles and I'm surprised it needs the timing chain replaced so soon? But i've read a few other instances of this happening on other forums.

Problem is, I can't get it booked in with my indy for another three weeks - considering this stretched timing chain probably first manifested itself back in February / four months ago, how potentially catastrophic is it to carry on driving the car on a daily basis for another three weeks until the new timing chain kit gets fitted?

If the worst happens, will the car go into limp-mode first before the timing chain snaps?

Cheers

[tee.gilding]

If the worst happens, will the car go into limp-mode first before the timing chain snaps?

I'm only guessing here, but I wouldn't want to chance it - surely a timing chain giving up the ghost would be a sudden and engine-destroying moment, and unlikely to have a limp-mode to save you from that happening. Reminiscent of the water pump failure on these things...

Worries me, because my coupe is on 70,500 miles...

[Z4M-2006]

I dare say you will be ok.

Bmw chain stretch is very common but very rare for it to snap ..

The eml and fault codes will suggest timing errors and can/ crank correlation errors

The chain will stretch gradually and twig the light intermittently then get more often as the chain stretches, the sensors see the stretch but the DME can only determine that it’s a timing error

[Ed Doe]

I've not heard of the 3.0si timing chain stretching... 2.0 engine is well known for it but never come across a 3.0si having it.... I'd be questioning that seriously. Ask your mechanic what the fault codes are - I'd me amazed if it's timing chain related.

Also if you get an intermittent eml you should be straight in to get the codes read - it'll store codes every time the light comes up so you'll have a good idea of what's up early enough that it's not done any damage....

[ph001]

First I have heard of it on here. Just doesn't quite add up to me - I mean, assuming you have nothing wrong with the tensioner, how can this happen to some cars and not others???

I'm with ED - I think this is highly unlikely on an N52.

[Ed Doe]

Also I'd like to add to this I had a 3.0si coupe from 50k to 105k - during this time I remapped it so it revved to beyond 7.5k, and I also tracked it, so it had a hard life and saw plenty of revs. My timing chain did not stretch.

The 2.0i engine is well known for this but yeah the 3.0si is well engineered and I've never come across this before....

[tug]

Wouldn't a stretched timing chain give off at least a different tone to the engine as well

I would edge my bet a little here and say at 70000 the tensioner would be more suspect. And the garage/dealer you took it to could perhaps be slightly swerving the truth a little.

[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"..

[Mr Tidy]

It does seem to happen now and again - when I was looking at E91s last year there was a 325i with the N52 engine for sale as spares or repairs that needed a new chain.

FWIW if the water pump goes they do go into limp mode if you don't stop - well my 1st Coupe did! But no way was I going to stop on a December night on an unlit N/S/L dual-carriageway with no lay-bys.

[NickDE]

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"..

HVA ?

[Ed Doe]

Hydraulic valve adjusters.

[ph001]

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????

[Jembo]

Crazy... my old E85 was on well over 85k when I sold her over 7 years ago & was still going strong when came up for sale a few years back.

Amazed this has happened, good luck with the fix

[mr wilks]

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

[A4RON]

Thanks for the replies all, very helpful

The European specialist garage I use certainly knows his stuff and he's got a high reputation here and very trustworthy; I've been using him for a few years now and he's a friend.

As for the car, I bought it just over three years ago on 43k miles, and since then it's been serviced regularly, never tracked under my ownership and thoroughly warmed up on every drive before opening it up a bit. My daily commute to work is 12 miles each way consisting mainly of straight A-roads at 60-65mph, so it's ideal for warming the car up

However, I have no idea how the previous owner treated it...

It's booked in for three weeks time, fingers-crossed nothing untoward happens between then