BHW Balance Shaft Module replacement

MOGolf · December 16th, 2008, 20:06

This thread is only for this topic. If you want to post about your car makng noises, see the links to other threads below and post in one of them.

As we learned from bad experiences, the BHW engine was equipped with at the factory with a chain driven balance shaft module. Chains and tensioners break, teeth strip off the sprockets, and nasty things happen to the engine.

VW obviously learned of this prone-to-failure design. Every engine they have with this design outside of North America got gear-driven balance shaft module replacements (not recalled, just replacement in the parts catalog and system). Finally they made one for the North American market BHW engine.

They issued a technical document to notify dealership shops of the replacement. However, they have not (as of this writing) actually made the information available via eBahn (the site they point to for everyone else to get repair info). The technical document merely states to refer to the repair manual for installation instructions. As of this writing, I am not aware that the information is actually there for North American VW repair technicians (I'm not one so I can't personally verify).

Oilhammer, who works at www.cardocautomotive.com, was alerted to the replacement parts, and less-than-helpful bulletin. I was able to track down the repair procedure published elsewhere in the world. That procedure was lacking in some steps.

We obtained the necessary parts, and together we installed them on my 2004 Passat Variant. The document link below provides a PDF with the repair procedure.

It is a supplement to other repair procedures that need to be followed as a part of the balance shaft module replacement. The other procedures are documented in the repair manual for the Passats. These include removing the front bumper cover, putting the lock carrier in service position or removing entirely, suspending the engine, timing belt replacement, and manipulating the subframe. This document does describe the necessary steps to take for loosening the subframe enough to remove the oil pan.

Read through the procedure. If you do not understand it, or do not have the other repair information, we do NOT recommend that you undertake the procedure. Failure to reassemble the car correctly can lead to poor handling which might lead to an accident. Failure to correctly reassemble the engine could also lead to a catastrophic failure.

You have been warned. You take on all responsibility for following this procedure, and all consequences of working on your car.

Having written that, I have to say I am very pleased with the outcome. My engine was making a lot of noise. It had very noticeable chain noise, though nothing terribly wrong was found on disassembly. The engine has virtually no lower engine noise after the surgery. I don't have to worry about imminent chain failure.

Refer to the following threads for further information about balance shaft issues:
http://forums.tdiclub.com/showthread.php?t=223941
http://forums.tdiclub.com/showthread.php?t=202297

I may revise the document at any time. Please get a fresh copy before undertaking the repair on any vehicle.

This procedure can be followed as a guideline for the other engines of the world that got this replacement design. However the parts vary depending on the engine. Vehicle disassembly/reassembly may also vary.

BHW Balance Shaft Module Replacement Procedure PDF

This document is a fairly large size (1377.8kb).

Edit to add:
World IMPEX has put together a kit price of the parts for those of you who are unable to get to oilhammer for help.
Geared Balance shaft module kit

www.advancedautomotion.com can supply parts too.

Bora Parts offers kits.

I have no association with these companies.

oilhammer · December 16th, 2008, 20:18

Nice write up!

Growler · December 16th, 2008, 20:34

ooo now I gotta go for another ride in your wagon to hear the difference

nice writeup Glen/Brian!

auntulna · December 16th, 2008, 21:05

Those of us with mortal mechanical skills are humbled by your collective tour de force in figuring this problem out, finding the corrective parts, and replacing them. Needless to say, I won't be doin' the fixin' around here Bobalouie! I will be in touch for eventual scheduling for the grand overhaul.

aja8888 · December 16th, 2008, 22:51

Glen & Brian: Thanks for your efforts and the fine write up.

Tony

leicaman · December 16th, 2008, 23:18

I read through the procedure and all I can say is wow....you guys have out guru'd yourselves here.

senez · December 17th, 2008, 06:39

The baking part is what gets me.

What? Like cookies?

DeliveryValve · December 17th, 2008, 06:51

Great procedure and write up MOGolf and oilhammer! Big THANK YOU!

I dig the specialized tools:

SST MOTOOL-GHOOO1
SST OHTOOL-BJOOO1
SST MOTOOL-GHOOO2
SST OHTOOL-BJOOO2

Question: I am not clear on the procedure of installing the new gear on the crank. Does the heated gear expand enough to freely slide on with your hands? Or do you need to tap it in place with the suggested seal installer?
Also, was there a particular orientation the gear is installed? Or you just choose any position and lock it in?

MOGolf · December 17th, 2008, 07:38

Yes you bake the gear like cookies. On the middle rack to ensure even heating. VW's procedure says to use a "commerically available hotplate". I prefer the oven. A hotplate will heat one side more than the other.

The gear slid right on with my gloved hands. The seal installer is just there to hold it with even pressure all around while it cools. You don't want it cooling at an angle.

No orientation for the gear. It is round

and not keyed. The procedure for pressing the intermediate gear into place ensures that all the teeth mesh correctly.

maktas · December 17th, 2008, 08:48

MoGolf,

You didn't make mention of the hex shaft. Did you do anything to it?

leicaman · December 17th, 2008, 09:08

Quote:

Originally Posted by maktas

MoGolf,

You didn't make mention of the hex shaft. Did you do anything to it?

I suspect that because of the geared setup there will be less lash pulsing due to the better integrity of the geared vs the chain setup.

MOGolf · December 17th, 2008, 10:33

We removed the hex shaft, found it labeled with the 'D' part number. I put it back in. Now we can find out how well this holds up over time. There is no written track record of geared balance shaft modules and the hex shaft oil pump drive that I can find.

The old BS module had an unlabeled hex shaft. No A and no D. No VW nor Audi symbols either.

maktas · December 17th, 2008, 10:37

Quote:

Originally Posted by MOGolf

We removed the hex shaft, found it labeled with the 'D' part number. I put it back in. Now we can find out how well this holds up over time. There is no written track record of geared balance shaft modules and the hex shaft oil pump drive that I can find.

The old BS module had an unlabeled hex shaft. No A and no D. No VW nor Audi symbols either.

So that I understand, the new BS asm comes with a new hex shaft? Or did you use the old one? It is interesting you mentioned the noise was eliminated, does this mean the hex shaft has minimal impact on the noise issue?

MOGolf · December 17th, 2008, 10:45

We used the new hex shaft that came with the new module. The module includes a new oil pump, hex shaft, balance shafts, bearings for shafts, intermediate gear, thrust washers for the gear, and gear bolt.

To my ears, the noises from my car were coming from the chain drive.

maktas · December 17th, 2008, 10:53

Quote:

Originally Posted by MOGolf

We used the new hex shaft that came with the new module. The module includes a new oil pump, hex shaft, balance shafts, bearings for shafts, intermediate gear, thrust washers for the gear, and gear bolt.

To my ears, the noises from my car were coming from the chain drive.

Ok.. I see, thanks!

I hope VW issues an officiall TSB soon... I want to use my extended warranty before it runs out. I also wonder if extended warranty work can be done by non-VW dealer shops?