BMW N43 timing chain tensioner

[brman]

I've just been looking at my wifes 2010 116i (2L N43 engine) as it occasionally sounds a bit rattly at start up so I suspected the cam chain.
The chain itself looks ok - not great, there is obvious wear marks on the side that rubs the guides, but not like it is badly stretched or anything.
However I noticed that, when engine off, it doesn't take much push the chain down (from the filler hole) and created lots of slack. It all looks ok (no flapping around) when running though. Immediately after stopping the engine there is a small amout of slack but not enough to worry me.

So my questions: Is this normal? Is the tensioner just spring loaded (in which case I have a problem) or hydraulic? If hydraulic, is there a 1 way valve? (in which case I still have a problem...)
Do these tensioners fail or is this indicating a more serious problem with the chain and guides?

From what I can tell by looking in the filler hole the guides look ok, but of course that could be deceptive. The obvious thing to do is get someone (I don't have time myself) to replace the chain/guides/tensioner as a set, but it is a car I would rather not spend that sort of cash on unless I really have to.

Comments are advice welcome!

[helix402]

Yes, the tensioners do fail. You can change just the tensioner. Easy job, just unbolt it. No timing tools needed.

Note-some people seem to have screwed the simple job up and messed their timing up changing the tensioner, so don’t diy it if you’re not confident.

[brman]

helix402 said:

Yes, the tensioners do fail. You can change just the tensioner. Easy job, just unbolt it. No timing tools needed.

Note-some people seem to have screwed the simple job up and messed their timing up changing the tensioner, so don’t diy it if you’re not confident.

Thanks Helix.
I would like to think I am a competent DIYer but that is not to say I am not capable of messing things up
About the only thing I can think could go wrong is if the chain becomes so slack (without tensioner) it can jump a tooth on the crank pulley. Hopefully that will not happen!

[brman]

I figured I should follow up on this.

I have now replaced the tensioner. A quick and easy job and nothing went wrong.
The original tensioner was indeed on it's last legs. It sort of worked but if the plunger was pushed in it would stick. The spring was weaker than the new one too.

Anyway, all done, and fingers crossed the chain lasts a good while longer.

[helix402]

brman said:

I figured I should follow up on this.

I have now replaced the tensioner. A quick and easy job and nothing went wrong.
The original tensioner was indeed on it's last legs. It sort of worked but if the plunger was pushed in it would stick. The spring was weaker than the new one too.

Anyway, all done, and fingers crossed the chain lasts a good while longer.

Good news!