[F30ed]

If the above theory is correct (sounds logical to me), chain stretch and plastic guides destruction is a function of number of engine starts. If you start the car and drive for 8 hours every day without stop, you can make N20 to 200,000 miles without a single problem. If you use ASS(auto-start-stop), you may damage your chains dozens time a day, and failure may occur much much sooner. This may sort of explain why some people make to 110K with no problem and some have chain ripped at around 50K, and why some have chain noise and some not.

[S4NoMore]

Originally Posted by BlueCrabMafia

You do bring a point to light also I didn't even think about before in the N20/26. The chain tensioner should be considered a maintenance item that gets replaced at intervals. It's a $60 part and given the probably failure of the chain guides on these engines, should be changed every 50-60K miles.

You're right about the tensioners being mechanically preloaded. Good point as well, regarding the timing chain tensioner as a preventive maintenance item.

However, the oil pump chain doesn't appear to have a separate tensioner part, and if it did it would be pretty invasive work. Is it integral to part number 6 in this drawing? Maybe...

[KGB_123_99]

Looks like ASS should be disabled. I think I've seen enough proof.

[F30ed]

Not a bad idea to check the tensioner.
Apparently it is just under the turbo actuator. Can be taken out, cleaned, replaced if needed. Plus you can check relative chain stretch if push tensioning boot with a rod thru the hole and measure how deep it goes.

The tensioner is part # 11 31 7 567 680.
$64 on Amazon.
I guess it is 20 minutes job.

[F30ed]

Interesting that there are 2 versions of the tensioner. The one shown in ISTA print - old version. It is shorter and has weaker spring inside (it is spring loaded as someone said above). Newer version is a bit longer piston move and spring is stronger too. Slightly longer reach and slightly stronger spring may make a difference for the chain slack at engine start and thus consequent parasitic forces and vibrations. Replacing tensioner might be a cheap and fast change to prevent expensive engine damage.

(As always, just a theory)

[F36420I]

Originally Posted by F30ed

Interesting that there are 2 versions of the tensioner. The one shown in ISTA print - old version. It is shorter and has weaker spring inside (it is spring loaded as someone said above). Newer version is a bit longer piston move and spring is stronger too. Slightly longer reach and slightly stronger spring may make a difference for the chain slack at engine start and thus consequent parasitic forces and vibrations. Replacing tensioner might be a cheap and fast change to prevent expensive engine damage.

(As always, just a theory)

Hello nice find!

Do you know the part number of the new one and tightening torque for it?

[F30ed]

Originally Posted by F36420I

Do you know the part number of the new one and tightening torque for it?

Same part number, you can see on the tensioner itself on the picture.
Tightening torque - 80Nm.

[S4NoMore]

Very interesting indeed, F30ed.

RealOEM indicates that 11317567680 is superseded by new part number 11318685091.

Further confusing, at least to me, is that the ECS product page for 11317567680 appears to show the revised tensioner.

Where did you find that photo?

[F36420I]

Originally Posted by F30ed

Same part number, you can see on the tensioner itself on the picture.
Tightening torque - 80Nm.

Thanks it looks that there's a new one

Part #11318685091 from 08/15/2016

Supersedes:


11317567680 (03/01/2007 — 12/28/2016),

11311439851 (04/01/2001 — 05/30/2007)

[bimmer456]

I have the 6 year 100k warranty just in case something like this happens to me. You would have been covered, but you should negotiate a good deal at purchase. You can also upgrade to this while you're still under warranty.

[F36420I]

Originally Posted by S4NoMore

Very interesting indeed, F30ed.

RealOEM indicates that 11317567680 is superseded by new part number 11318685091.

Further confusing, at least to me, is that the ECS product page for 11317567680 appears to show the revised tensioner.

Where did you find that photo?

lol you are quicker than me

[F30ed]

Originally Posted by S4NoMore

Where did you find that photo?

I did a quick search by part number and found link below. Apparently same tensioner is used in E46 engine. There is video there, the guy visually shows how much stronger is the spring in newer edition. I would let you guys to research further on the revisions, I hope all this leads to something useful and positive.

http://www.impee.co.uk/bmw_timing_chain_tensioner.htm

At the same time all this may turn to nothing if everyone has new version of tensioner. Or maybe it still makes sense to replace it as over the years in high heat environment spring may loose some strength or worse - starts leaking oil and thus delivers less tension.

[S4NoMore]

I think it might be that the old tensioner shown is from older generations. Probably worth checking though, it's visible just by popping the hood.

I got all curious so I took a look, it appears my 2012 N20 has the updated style. But there could be another revision that isn't discernible visually.

[etinifni]

I'm kind of wondering what BMW will do if a car that has already had timing chain replaced under warranty craps out.

[BlueCrabMafia]

Looks like BMW has a habit of designing insufficient tensioners. They did the same thing with the M62TU tensioner which has the same chain guide issues the N20/26 is having.

I'll be ordering the new revised part tonight and replacing the old one with the quickness.

[S4NoMore]

Originally Posted by BlueCrabMafia

Looks like BMW has a habit of designing insufficient tensioners. They did the same thing with the M62TU tensioner which has the same chain guide issues the N20/26 is having.

I'll be ordering the new revised part tonight and replacing the old one with the quickness.

Please report back with whatever differences you can find between the tensioners. Good luck!

[F36420I]

Originally Posted by BlueCrabMafia

Looks like BMW has a habit of designing insufficient tensioners. They did the same thing with the M62TU tensioner which has the same chain guide issues the N20/26 is having.

I'll be ordering the new revised part tonight and replacing the old one with the quickness.

Please give us some pictures when you have it

[BlueCrabMafia]

Originally Posted by F36420I

Please give us some pictures when you have it

I will. One thing I wonder about though is how much oil will come out when the tensioner is removed given its location. I've previous cars I've done this too, the tensioner is in the top of motor near the head.

May have to wait until my next oil change to perform this.

[S4NoMore]

Originally Posted by BlueCrabMafia

I will. One thing I wonder about though is how much oil will come out when the tensioner is removed given its location. I've previous cars I've done this too, the tensioner is in the top of motor near the head.

May have to wait until my next oil change to perform this.

N20 primary tensioner is in the head as well. Nearly all the oil settles into the oil pan after several minutes, so I wouldn't worry about it. There will be some oil, but it won't come pouring out of the head. 1 shop towel should suffice.

[BlueCrabMafia]

Originally Posted by S4NoMore

N20 primary tensioner is in the head as well. Nearly all the oil settles into the oil pan after several minutes, so I wouldn't worry about it. There will be some oil, but it won't come pouring out of the head. 1 shop towel should suffice.

Gotcha. I hadn't actually looked at it yet on my car, I was just going by the picture posted here. It looked close to the waste gate so I thought it was farther down.

[S4NoMore]

Originally Posted by BlueCrabMafia

Gotcha. I hadn't actually looked at it yet on my car, I was just going by the picture posted here. It looked close to the waste gate so I thought it was farther down.

It's deceiving, in part because the wastegate actuator is angled upwards and the motor leans over towards the exhaust by 30 degrees.

[Gamb1t]

This is one of the best thread on this forum. Investigative crowd sourcing FTW!
I'm over at the x3 forum and they have a number of timing chain issues there. I wonder the x3 drivers are more into ASS...