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N20 Timing Chain replacement

Specific discussion about the E89 2009 Z4 (sDrive35is, sDrive35i, sDrive30i, sDrive23i)
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Bellypopper
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N20 Timing Chain replacement

Post by Bellypopper » Tue Feb 20, 2024 12:13 am

Hi All

After my initial post on which N20 model would be the best choice, I was left somewhat confused, with the split of opinion between older car lower mileage or newer car with higher mileage, this has got me thinking, so here is question number 2:

With the N20, is the chain replacement purely based on mileage, or does age come into the equation? I understand the chain won’t perish like a belt, but the guides are plastic which could become brittle with time I suppose? I have seen 9 years or 90,000 miles quoted by a BMW independent, would this seem about right? Do the later N20 engines with the white guides go for longer or are they just less likely to cause issues early?

Cheers
Russ

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B21
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N20 Timing Chain replacement

Post by B21 » Tue Feb 20, 2024 9:49 am

The cam chain ‘issue’ is vexed…some cars have seen failures as low as 35k miles..more typically 65k-85k…many cars never have an issue.

Correlations that seem to exacerbate the problem are use of stop start, short journeys poor (standard) BMW oil change intervals.

The revised set up in 2015 had different material guides, heavier duty chain, revised sprokets and revised oil pump drive which could also suffer..if you do the upgrade it’s important to do all aspects.

That’s really the only issue on N20..with a good oil change regime those engines should do 200k miles easily.
We choose to go to on with this endeavour at this time and do the other things, not because they are easy, but because they are hard…
A very modified Atacama Yellow 35is :thumbsup:

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Deepseaskateboard
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N20 Timing Chain replacement

Post by Deepseaskateboard » Tue Feb 20, 2024 9:58 am

Some N20 engines have failed, they revised the guides.

Not all earlier N20 engines will fail because of the guides.

If you are worried about it, it’s best to find a car with the revised parts, or find a 6cyl version.

All E89s are getting on a bit now with age, and there is more to go wrong than just the engine. Keep some money aside for fixes and you will be fine.

Personally I would be looking for the usual, FSH, unmodified, well looked after. You can also get an o-ring pick and see if you can induce a rattle in the chain through the oil filler cap.
If you can, it’s no good, even if slight.

It’s an easy check you can carry out periodically so you could book it in before a catastrophic failure occurs.

I have a 2012 20i, it has full BMW history, does less than 4k per year and runs sweet. I have had it for nearly eight years now.

You would never be able to find out if the car has done many short trips before.

I think the job can be done for about £1200, so if you budget that in, you will be ok. You won’t be able to use it as a negotiation point on price though.

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