BMW 3 Series Coupe (E46) - BMW 318CI Timing Chain Guide (N46 Engine) N46-20 - pbirl

My garage checked today at a service and told me the upper guide on the timing chain had split - they showed me and it has - a nice clean split! A known issue - apparently. There was no noise, rattle or any other indication from the engine, which has covered 58K miles, has a full service record and was running nicely.

I'm told they will replace the upper guide and put in a new tensioner, as the original BMW item isn't long enough and therefore doesn't push the guide in far enough to create adequate tension on the chain.

Will this be sufficient or would it be better to replace all the guides, chain, etc? The garage seem to think not, unless the chain is loose or rattly after the fix, which they think unlikely. Also, is there a stronger guide available or is it just another feeble plastic one? I'm told by the garage that if the chain is adequately tensioned the guide is unlikely to break or be damaged.

I don't see the point of a timing chain if it has to be repaired or replaced - may as well have a belt. Seems like very poor basic engine design by BMW.

Edited by pbirl on 07/02/2015 at 01:56


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