Misdiagnosed balance shaft gear failure

[Splint]

So my W211 E350 gave me the dreaded P0016/P0017 codes. I wound the crank around to 305 degrees and sighted the inscriptions through the cam position sensor holes and noted that one was perfectly central and the other was slightly off, not as far off as some of the examples I've seen on youtube, but off none the less.

I pulled the engine out and got the timing cover off only to find the balance shaft gear (all gears driven by the timing chain for that matter) were in excellent condition. There were no signs of wear at all, everything looked like new.

I've not been able to confirm timing chain stretch as the closest to a stretch test I can find is the valve opening relative to the crank angle. I tried to follow the data set out in WIS (no actual procedure provided, just data) but found that it wasn't making sense as the angles were so different that it would be completely impossible to the chain to stretch that far without breaking or causing the engine to not even run

I ended up checking the links around the cam gears and found minimal movement which would suggest the chain has not stretched.

There does appear to be some wear on the chain guides and I was wondering if anyone has had experience with the guides causing P0016/P0017 errors.

Could this also be a sensor issue? I also replaced the magnet on the exhaust cam so I wouldn't expect both P0016 and P0017 errors.

Any thoughts?

[Ivanerrol]

What is you engine number? Is it in the range of affected engines?

[Splint]

I checked all that a while back. It's an 06 build so it was one of the last with the bad balance shafts.

[Ivanerrol]

The balance shaft issue was cured for cars past October 2006. (MY - model year birthdate)
I test drive a late 2006 W211 E280 a few weeks ago - it didn't have an balance shaft issue - the engine number was past serial number 2729 30 468993

Have you read through this? http://australiancar.reviews/mercedesbenz_M272.php

[Splint]

I just checked, my car is a Sep 06 build but the serial is 272964 30470157, so outside the effected vehicles. This is very strange, the P0016 and P0017 codes have been logged and return immediately after being cleared and the inscriptions which can be seen through the cam position sensor holes do not align perfectly with the crank at 305 degrees.

Can there be any other causes for this? Maybe chain tensioner not applying enough pressure? I don't believe there is excessive wear on the chain guides either , they actually look pretty good.

Can there be an issue caused by the magnets at play here? Every single reference I have ever seen regarding the P0016/17 codes indicates a worn balance shaft gear, but this appears not to be the case here.

The pulse wheels appear to be in perfect condition. The dowels which index the pulse wheel to the cam adjuster have a reputation for shearing, all of the dowells on this engine are in tact and in good condition, so no slippage of the pulse wheel.

[Ivanerrol]

The M271 four cylinder engines had problematic tensioners.
They are one offs. If you remove it then a new one must be installed.

Your engine series still had issues with the cam magnets and cam cover seals. These issues weren't cured up until 2008.
Both retroactively fixed with updated bits.

Just watching this : https://www.youtube.com/watch?v=xohSv1epRHU

[Ivanerrol]

More info : http://www.benzworld.org/forums/attachm ... ne-dtb.pdf

[Ivanerrol]

More info from a Benz forum

P0016 is a generic OBDII code that could be other things besides the DTC 1208 that indicates balance shaft failure.

You probably need to go to an independent Benz specialist with a Star Diagnostic reader to get the codes interpreted more intensely.

[Splint]

Thanks, mechanically it's in good shape and showing no signs of failure with 112,000 km on the clock (I understand the balance shaft gear typically fails between 95 and 130 thousand km if it is going to fail). I contacted MB Australia and the dealer it was last serviced at and neither could confirm whether the balance shaft was one of the bad ones. The suggestion was that even though the build date was a month before the last of the bad shafts were fitted, the engine number was higher than the last known bad shaft so it is probably OK. I think I'll put it back together and take your advice re having a MB specialist have a look at the car.

Cheers

[Ivanerrol]

From what I've read on overseas forums. You need a specialists with a specific mercedes Star diagnostic computer.
Allegedly - The ordinary code readers will not give the full story.