B5 BHW engine noise revisited

to those that have seen inside these:
Is the oil pump hex bore hobbed or rounded by this back-lash issue, or is the metal distortion limited to the hex shaft and to the #2 balance shaft only?

The metal on both the female #2 balance shaft AND the male hex shaft gets rounded out. Our present thinking is that the loose fit from the factory allows the parts to beat themselves up from the loads placed on them to drive the oil pump, and TDImeister pointed out that the balance shaft itself may also have a role as it may set up some sort of harmonic distortion.

What I mean by that is, if there was only a load placed on the parts only in one direction then the parts would not beat back and forth, and thus logic would dictate they would not wear any more. But the fact that they DO wear would mean the 'slop' develops a larger amount of play because the load does in fact go in both directions as the engine is running.

This is hard for me to describe, but if the balance shaft periodically (perhaps every revolution) changes its RPM slightly then the load on the oil pump would not be constant. In other words, it would work like an impact wrench to turn the oil pump rather than a drill. Follow me?

Route 66 said:

How did the 2.0 PD Engines w/manual transmissions deal with the vibration issue? ie no counter balance assembly.

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I am assuming that the DMF was able to do the damping of vibrations in those models.

Keep in mind that the bore is larger on the 2.0L versus the 1.9L, so larger (heavier) pistons require larger (heavier) crankshaft counterweights, which on VAG inline engines with their relatively small 88mm bore spacing is just hard to do.

There are some gas 2.0L VAG inlines that also use dual balancers, but they likely do not have the NHH issue that a diesel does because the pistons and rods are almost certainly lighter and of course the stress placed on them are less (compression ratio).

The new 2.0L CR TDI also uses dual balancers, but they are GEAR driven.

Lug_Nut said:

to those that have seen inside these:
Is the oil pump hex bore hobbed or rounded by this back-lash issue, or is the metal distortion limited to the hex shaft and to the #2 balance shaft only?

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The bore in the oil pump has a slight amount of chatter marks, but because there is so much more contact length (= more square area = lower PSI = less distortion of material) it does not seem to be effected to a point of concern. Perhaps Oilhammer can comment if he has seen anything different on the oilpumps he has removed.

To answer a question earlier, sorry no exact dims, as I am 120K from home, the hex shaft is about 6mm across the flats and about 3" long. There is about 3/4" inserted in the balance shaft (BS) hole (NOT VERY MUCH) + 1/4" gap between BS and oil pump shaft, with the balance being inside the oil pump shaft.

I should of explained a previous comment a bit more. EDM means electrical discharge machining. It is a CNC controlled process. It is good for high precision and hardenned metals, like this balance shaft. A new larger hex hole could be perfectly created in the end of the damaged balance shaft.

As for the idea of threading a hole and using a bolt through the oil pump shaft into the balance shaft (mentioned a few pages back)...I will put together a quick opinion on that. There would be some serious issues. The space (between oil pump and BS) could be dealt with a spacer, however, a bolt requires creating friction between surfaces to work properly. This is done by torquing it (stretching it and appling high clamping loads). Because the pump is doweled, the balance shaft would have to move to the right location for the bolt length and torque setting. This could only lead to problems for either oil pump failure or the balance shaft thrust bearing failure (and spur gear failure). In addition, generally a bolted friction fit is just not used for transmitting torque for many reasons. I can not think of a single application where this has been done, outside of some crank handles or something like that, where even then there would probably be a toothed or splined interface between surfaces. If you can think of some good examples, please list them. I am not trying to be negative and cut-off alternative ideas. Just telling you what I know from a design point of view on this particular point.

TDIsyncro said:

.... toothed or splined interface between surfaces.....

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If there is talk of an exchange program for the #2 balance shaft. Would it be feasible to redesign the interface since there might be some machining done to the spent balancer anyways? Maybe instead of using the hex arrangement, you could use a splined arrangment coupled with somehow using a dowel or pin to keep it from moving.... Just thinking out loud.

If you can find a way to re-engineer it, and you think it will work, go for it! I am all for it, but will be the first to admit that sort of thing is beyond my expertise.

I have thought that a tight-fitting spline drive, like a clutch disk uses on an input shaft, would be best...but have no idea how to do this.

DeliveryValve said:

If there is talk of an exchange program for the #2 balance shaft. Would it be feasible to redesign the interface since there might be some machining done to the spent balancer anyways? Maybe instead of using the hex arrangement, you could use a splined arrangment coupled with somehow using a dowel or pin to keep it from moving.... Just thinking out loud.

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A spline drive is a vary good product. Would it be nessisary, probably not, if compared to an upsized properly fitted hex drive (= stronger and better wear than OEM). However, one would have to look at the cost of creating the splined hole and shaft end vs the hex shape. If there was minimal cost difference I would say its a very good option. As you mentioned, this would be for damaged hole BS units only. The EDM proces can create the spline in the BS. I would think in such a scenario, the shaft would remain the same length, the hex size would remain OEM in oil pump, and there would be a fillet transition to a spline drive at the BS. There would be no need to put a dowel pin in, nor is there room. If you look at the pics, the hole is mostly internal to the bearing surface, with only a small shoulder on the end.
Anyways, its a good option to mention.

I've been following this thread as I just bought a low mileage 2005 Passat with 35,000 miles. It sounds mostly like a normal diesel at idle. It seems as though I will need a solution at some point in time. I would also be interested in the metalnerd solution. Keep up the good work you guys!!

anouther update..

Metalnerd and myself have discussed a few more options for replacing the internal threaded hole in the hex shaft. I think we have a solution, but he is just waiting to hear from the machine shop on how it will fit (and work with) the production.

I also discussed Oilhammer's BS exchange program idea with him. He has a meeting booked with his EDM vendor regarding the "oversize hex hole repair" to damaged BS. A few other items that will have to be checked on an exchange program is bearing journal size, bearing condition and end play. Gear backlash would be anouther item to check. There would also have to be some guide lines to know if a damaged assembly will fit in the exchange program (repairable or damged in other ways, such as excess wear from poor maintenace practices). Since VAG does not consider this a servicable part, the tolerance range and rebuild procedure will have to be defined by us. Best way to do that is measure clearances on a new assembly (and journal size). That would be the base size. Oilhammer & MOGolf, if you guys have any thoughts or ideas here, jump in. It would be good to locate replacement journal bearings to create "fresh" exchange assemblies.

Well, I do not have another new one here, but I do have a used one here with 244k miles on it, and the other I sent him only had 96k on it, so those two compared (if taken apart and measured) might give some indication of wear normalcy when compared to new. I could certainly order in another new one but I'd then be stuck with it until I sold it.

The 244k mile one here now has essentially no perceptable play (without any instruments put on it, obviously there must be some clearance between the moving parts).

I do have a new hex shaft here, all by itself.

oilhammer said:

Well, I do not have another new one here, but I do have a used one here with 244k miles on it, and the other I sent him only had 96k on it, so those two compared (if taken apart and measured) might give some indication of wear normalcy when compared to new. I could certainly order in another new one but I'd then be stuck with it until I sold it.

The 244k mile one here now has essentially no perceptable play (without any instruments put on it, obviously there must be some clearance between the moving parts).

I do have a new hex shaft here, all by itself.

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Perhaps between now and the time this solution is in motion you might have anouther balance shaft replacement. But you are right, we can do some comparisons in wear vs mileage. I suspect that the balance shaft journal itself will have no perceptable wear if it has seen nothing but 505.01 oil and regular changes. The bearings should have some wear. I have parts of mine on the bench still, and they have 37k on them (along with the bearing shells. So that is three units for comparison.

So there are in fact seperate bearing shells inside the assembly? Interesting. I figured they'd just ride them right on the case iron housing.

So that raises yet another question: why the heck don't the service seperate pieces of the assembly???? Any part numbers on anything in there?

I'm in for one.

Thanks for the homework!

oilhammer said:

So there are in fact seperate bearing shells inside the assembly? Interesting. I figured they'd just ride them right on the case iron housing.

So that raises yet another question: why the heck don't the service seperate pieces of the assembly???? Any part numbers on anything in there?

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Yes, bearing shells, very similar in design to rod bearings or main bearings. Yes, why don't they service pieces? It probably means the BS module was designed and built in its entirety by a separate vendor (like bosch pumps or garrat turbos)? If you split the unit you have on hand and looked for all the various part numbers on it, it might tell an interesting story.
(I just spent the last hour looking for those shells..all I could find was the balance shaft lobes - I must of tossed them during my last clean-up. )

Will the proposal for oversizing the BS bore, thus requiring the use of a dual OD 'hex' shaft, prevent that dual dimension hex shaft from being pulled out through the oil pump?
Is that a problem? It was my understanding that the BS was installed, the oil pump slid onto its dowels, and the hex shaft was poked through the pump and into the BS. A dual dimension hex may require the hex shaft as the starting piece, with sticking the BS on one end of the 'hex', the pump on the other, and then placing the three, as an assembly, into the housing.
No?
Not a problem this time since the BS has to be machined or exchanged and therefore has to come out, but any oil pump work after this will require BS removal?

Lug_Nut said:

Will the proposal for oversizing the BS bore, thus requiring the use of a dual OD 'hex' shaft, prevent that dual dimension hex shaft from being pulled out through the oil pump?
Is that a problem? It was my understanding that the BS was installed, the oil pump slid onto its dowels, and the hex shaft was poked through the pump and into the BS. A dual dimension hex may require the hex shaft as the starting piece, with sticking the BS on one end of the 'hex', the pump on the other, and then placing the three, as an assembly, into the housing.
No?
Not a problem this time since the BS has to be machined or exchanged and therefore has to come out, but any oil pump work after this will require BS removal?

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yes, this is true. It is not an optimum solution from that point of view. The other way around it is installing a sleeve to get it back down to standard size. We would need to find a good method to keep the sleeve in the BS.

Not to dwell on the welding idea again but what if we used a 'weld bond' type glue instead of heating up the parts? I have used this stuff in the past to patch gas tanks and mufflers. It dries as hard as metal and can be machined. What if a new shaft was insterted with the weld bond on it? Maybe that would help hold it in place and prevent it from wobbling loose? I need to do something on my car soon as it is getiing noisier. Im living on borrowed time no doubt.

An observation - the hardness of many wear parts such as the Balance and mating Hex Shaft are not uniform throughout the part. It is more often than not a surface effect which is the engineered result of the sequence of final heat treatment, machining, and perhaps a direct chemical surface treatment to boot.

So not only is it possible that removing .003" would expose metal with inferior properties, but certain that the machining process itself will have an [highly localized] effect. The bottom line is that without a post-machining heat treatment and/or surface treatment the durability of the fix is at best uncertain. Including small-lot treatments will $++ the fix.

Disclaimer - I don't know for a fact how VW prepares these parts, so it is possible that this fix is viable. Nor do I know what the costs for a straightforward replacement are so perhaps additional treatment(s) don't sour the economics of the fix. You'd have to ask someone with specific knowledge to be sure.

What I do know is these two details are worth minding.

RI_TDI said:

An observation - the hardness of many wear parts such as the Balance and mating Hex Shaft are not uniform throughout the part. It is more often than not a surface effect which is the engineered result of the sequence of final heat treatment, machining, and perhaps a direct chemical surface treatment to boot.

So not only is it possible that removing .003" would expose metal with inferior properties, but certain that the machining process itself will have an [highly localized] effect. The bottom line is that without a post-machining heat treatment and/or surface treatment the durability of the fix is at best uncertain.

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This is a valid point to be explored. I could send my balance shaft lobes to be be tested..carefully sliced to test the depth of hardness.

Radman said:

Not to dwell on the welding idea again but what if we used a 'weld bond' type glue instead of heating up the parts? I have used this stuff in the past to patch gas tanks and mufflers. It dries as hard as metal and can be machined. What if a new shaft was insterted with the weld bond on it? Maybe that would help hold it in place and prevent it from wobbling loose? I need to do something on my car soon as it is getiing noisier. Im living on borrowed time no doubt.

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I have some products, similar to what you mention. There is potential there. But there is also potential for the bond material to hammer out over time. It would be a gamble for someone to experiment with themselves..just as I have gambled on certain things myself.

I keep coming back to a vision of an interference fit insert in the BS, either keyed or splined for torque transmission to the oil pump without slipping, retained in place by a circlip or snap ring, and having a standard hex ID to allow use of the standard pump drive shaft.
The use of an insert (bronze? Urethane? tool steel?) avoids most of the BS material hardness and depth of hardening issues, allows the re-use of BS already having hex damage, allows tightening the clearance tolerance between the hex drive shaft and the BS, allows removal of the drive shaft for pump removal. Also allows removal and replacement of the insert should it not outlast the other components.

Boring the BS with a new cylindrical hole, while keeping a lip for a retainer ring, as well as wire EDM cutting new, tighter hex in round stock of nearly press fit size, then cutting a keyway in both the BS and round stock insert....
Push in the insert, push in the key, install the circlip....
Damn, it seems too simple....

Lug_Nut, I forwarded your post to Metalnerd. Thanks for sharing your vision.

Update from yesterday.

Metalnerd has been to his local EDM shop. Sounds like there is no problem with opening up the hole. He will have pricing on that part of it shortly. The BS shaft journals on the sample he has have only .0002" wear on them (at 99k), so looks like a good candidate for starting the process off. I think he is measuring the running clearance today and then checking into bearing shell sources. This way an upgraded BS can come in a reconditioned assembly.

Interesting bit of trivia I found. The BVH and BRT 2.0L TDI engines used in the current VW Sharan also have a balance shaft module, BUT it is a gear-driven type however it fits under the same front cover as our chain driven ones in the BHW. I wonder if this setup could be adapted?

FWIW, the Sharan's 2.0L TDI is also a SOHC 8-valve PD engine. I'd love to see a nice blow-up pic of the entire engine if anyone on that side of the pond could find one.

oilhammer said:

Interesting bit of trivia I found. The BVH and BRT 2.0L TDI engines used in the current VW Sharan also have a balance shaft module, BUT it is a gear-driven type however it fits under the same front cover as our chain driven ones in the BHW. I wonder if this setup could be adapted?

FWIW, the Sharan's 2.0L TDI is also a SOHC 8-valve PD engine. I'd love to see a nice blow-up pic of the entire engine if anyone on that side of the pond could find one.

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Knowing VW, it will be much cheaper than the BHW assembly, but not fit the BHW, or much, much more expensive than the BHW assembly and fit. Choose one

oilhammer said:

Interesting bit of trivia I found. The BVH and BRT 2.0L TDI engines used in the current VW Sharan also have a balance shaft module, BUT it is a gear-driven type however it fits under the same front cover as our chain driven ones in the BHW. I wonder if this setup could be adapted?

FWIW, the Sharan's 2.0L TDI is also a SOHC 8-valve PD engine. I'd love to see a nice blow-up pic of the entire engine if anyone on that side of the pond could find one.

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I am a big fan of the gear driven unit. The new CR in NA has the gear driven BS module too. In both cases we are dealing with a crank and BS swap. Any guess on rod bearing sizes and main bearing sizes?
Oilhammer, if you ever get your hands on a broken 2.0FSI, keep the BS module. I bet it bolts onto the BHW. It is a chain drive, but has the spring loaded driven sprocket to absorb the torsion vibrations from the crank.

BRT engine oil lubrication parts

oilhammer said:

Interesting bit of trivia I found. The BVH and BRT 2.0L TDI engines used in the current VW Sharan also have a balance shaft module, BUT it is a gear-driven type however it fits under the same front cover as our chain driven ones in the BHW. I wonder if this setup could be adapted?

FWIW, the Sharan's 2.0L TDI is also a SOHC 8-valve PD engine. I'd love to see a nice blow-up pic of the entire engine if anyone on that side of the pond could find one.

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Like this?


Note: The hex shaft of the oil pump goes into the balance shaft just like the BHW. This engine just won't get the jerking pulsations of a chain drain though.

Parts list:
03G 105 021 K crankshaft
038 105 263 H timing belt pulley (but we should be able to use the existing one. Passat engines have different ones depending on the engine cam.)
03G 103 295 K balance shaft module
03G 103 305 A drive gear
N 911 213 01 drive gear bolt
038 103 171 S rear engine sealing flange with sealing ring and impulse rotor (different sensor arrangement?)

Bolts for the module to crankcase:
N 909 775 02 BOLT (1)
N 106 014 02 BOLT (5)
N 910 512 01 BOLT (1)
(ETKA lists 7 bolts, but there are 8 that hold it to the block per another picture.)

Also Passat engines BVE, BWV, BMA, BKP, BMP, BUZ, and BMR. These are all transverse mounted engines.

Bearings are the same as BHW.
These engines use an oil pan with the oil level/temperature sensor.

I have the procedure for installing this module (requires two people and a block of wood when installing a new module).

Ah, see... ask and you shall receive! Thanks, MOGolf!

So, it looks to me like the gear type setup may work in the BHW engine. The front seal holder that covers the drive chain on the BHW is the same part that covers the gearset on the engine pictured above.

The only issue we have to determine is will the BHW's sump cover (oil pan) fit over that engine's BS module and oil pump, and will the oil pump pickup tube be in the same spot.

Reason we have to use the BHW oil pan over is because of the difference between transverse and longitudinal engine mountings. The engine pictured above fits transverse applications.

Notice they still use that pesky hex-shaft, but at least the stupid chain is gone and as MOGolf stated, the hex shaft won't get that variable loads caused by the chain slacking and tightening as the engine runs.

I bet the engine runs smoother as well because the balance shafts remain perfectly timed with the crank due to the gears.

Now to find out of these parts will even fit....

I finally got around to doing this on tuesday. Car has around 130000 miles. Timing belt had been done by previous owner at around 115000 miles so we did not bother changing it. We only replaced the hex shaft with a new one. There was visible wear on the shaft however it was nowhere near failure yet. The car was noisy and still is albeit less. The new shaft has some amount of play in it as it is stock size. I think my alterantor pulley is also making noise. The gears and chain / chain guides were fine so we left as is. We removed the balance shaft module entirely from the bottom of the car. Took 4.5 hours to do the job. Upon next TB change there should be a better shaft available and I will replace again along with the chain, gears etc. (providing I still have the car at that time)
I have a hard time seeing how one of these could fail completely! The must have to wear out and strip completely.

Radman said:

I finally got around to doing this on tuesday. Car has around 130000 miles. Timing belt had been done by previous owner at around 115000 miles so we did not bother changing it. We only replaced the hex shaft with a new one. There was visible wear on the shaft however it was nowhere near failure yet. The car was noisy and still is albeit less. The new shaft has some amount of play in it as it is stock size. I think my alterantor pulley is also making noise. The gears and chain / chain guides were fine so we left as is. We removed the balance shaft module entirely from the bottom of the car. Took 4.5 hours to do the job. Upon next TB change there should be a better shaft available and I will replace again along with the chain, gears etc. (providing I still have the car at that time)
I have a hard time seeing how one of these could fail completely! The must have to wear out and strip completely.

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It is not the hex shaft that fails completely, it is the chain....without warning. You should have replaced it!