Gear driven balance shaft failure

Here is a picture of the gear driven balance shaft assembly that failed with about 10,000 miles. Or did I screw up installation in March 2009???
http://pics.tdiclub.com/showphoto.php?photo=57095&size=big&cat=500&ppuser=65009

Picture was provided by mechanic that was inspecting car described in post titled "troubles in Montana" I have not seen the gears first hand but it looks like the balance shaft gear came apart and filled the engine with metal shavings.

I guess someone should send me a link showing how to post a picture. It's in my album under "mopractice"

It is hard to say what caused the balance shaft gear to disintegrate like that just from the picture. I am speculating but it looks like either the balance shaft gear came loose or the entire balance shaft module shifted a small amount due to bolts not being torqued correctly. The mechanic doing the inspection should be able to tell you the likely failure mechanism once he pulls the balance shaft module.
Any other damage to the engine due to shavings and metal in the oil? What is the parts list needed to fix it now?
Once he gets the balance shaft module out supply some more pictures of the failed components and the likely source of the failure.
This is an unfortunate event we can learn from.

Mark

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bummer. your intermediate gear probably came loose. BS module can't really shift once it's in place unless the dowel pins were left out.

I am just going from my past experience with gear boxes. We had a poorly calibrated torque wrench that under torqued some securing hardware and shims. The shift in the gear box was less than .25 mm. But it caused a gear to not to be perfectly square with the gear it was driving. This led to some gears having the entire load placed on the outside edge of the gear teeth causing a force that broke a key, letting the drive gear chip and eventually fall off.
This was heavy, low tech stuff so such a problem on a BS module would cause some big problems.

For all to see...

The intermediate gear stayed tight. The balance shaft gear came loose or was somehow defective. The assembly did have dowel pins and was properly torqued.

It will be awhile before I can tear it down and get a close look. I have an engine from a flood car that I need to remove and open up before I remove this one.

Well lets hope this is an isolated incident and not the beginning to a string of gear drive BS module failures....

The way it looks to me is that the intermediate gear bolt backed out. The gear is clearly cocked at a severe angle, and bolt appears too far out. A brighter clearer picture would help, but I know that is hard to do with dark oil covered parts.

I can only *speculate* that the intemediate gear bolt wasn't torqued properly the 20 Nm + 1/4 turn while the gear was being pressed forcefully against the other gears.

Regardless of how it happened, it can be fixed. (I hope the car was not run on low/no oil pressure.) I would suggest replacing all the gears, and bolts associated with them.

Parts list:
03G 105 212 D crankshaft gear (pull off old, heat and install a new one)
03G 103 305 C small balance shaft gear
N 911 213 01 bolts for small gear (x 4)
038 103 085 C crankshaft seal

Intermediate gear pieces (you will have to special order the gear)
03G 103 488 A gear
03G 103 323 A thrust washer (x 2)
03G 103 580 hub
N 104 096 01 bolt

www.worldimpex.com was able to special order the parts when I fixed the one that was MINIONed.

Make sure the thrust washer between gear and module is properly positioned. Make special note of how the old pieces come apart so that you put the new ones together correctly.

I enhanced the photo a bit in Irfanview and it sure looks like the intermediate gear is cocked. If the bolt is still tight, could the bearing have collapsed?

^^ Does a failure like this not also cause a complete failure of the engine? Similar to that of the chain-driven module?

Here is the photo enhanced and cropped:

^^^ If I am not mistaken, it looks like the intermediate gear is messed up.
Question, did you put the proper pressure on the gear with a wood block and along as stated it was torqued down properly.

It might be the angle of that shot but did the intermediate gear bolt hit the inside of the oilpan?

I don't think it would have. There is plenty of clearance there.

mopractice could be second guessing himself forever on 'Did I do xx or didn't I?" We'll never know for sure without a video of the event, or dozens of witness that all swear he did or didn't do xx.

I wish him well in fixing the car, and moving on, instead of second guessing.

The oil filter should have caught any particles from going anywhere through the engine, other than the splash in the pan. Clean out everything as best you can, fix it, run a short while with new oil, drain, install another new filter, refill and go.

This is not the first time someone has not properly followed the directions for this job.

Sure looks like someone just stuck the BS module up in place with the internediate gear bolt in the 'slightly snug' postion it is in for shipping and did not loosen and press it properly into place then tighten back down like you are supposed to do.

Volkswagen has been building these like this since 2006, if this was an issue I think we'd have heard about it by now.

What year did they start building the chained units?
When did we hear of the failures on those?

Lug_Nut said:

What year did they start building the chained units?
When did we hear of the failures on those?

Click to expand...

2004. And I heard of issues with them before I even purchased my car in April of 2004.

They were also using chain driven dual balance shafts in some gas engines prior to that, but a slightly different design. We did not see any of those until just recently, and I have already seen one of those broken too. The later BDC 2.0L gas engine (like in a 2003 NB) has them.

This happened to my passat

My intermediate gear came lose after 10k miles. This thread however is confusing. Someone says the balance shaft gear came lose. But is see a loose intermediate gear in the picture. The intermediate gear looks just like mine. Lose as a goose.

Was the gear properly lashed and torqued.

Was the cause ever discovered. Was the repair successful? How many miles since the repair?

Thanks for the wounder full information.