Can't isolate wobble on vibration dampener on AAZ engine. With video!

[Henchman]

So after doing my alternator pulley upgrade, I tackled the wobble in the vibration dampener pulley.

The waterpump was SHOT, so I replaced it.  PS pump had some deflection in the shaft, so I replaced it with a used ps pump with no play.  Replaced all pulleys with refurbed pulleys, all straight, blasted and painted.  Replaced dampener with a used one that also received the blast and paint treatment.  Even redid the PS adjustment bracket!  All new bolts torqued to spec.  While I had the pulleys off, I took a long look at the crankshaft sprocket and bolt.  Still on tight, no movement, appears to be on square.  I didn't want to pull it at this stage, but looks like that's my next step.  I even backed off on the fueling to more of an eco mode.

http://www.youtube.com/watch?v=uAl_8GwCLXw

What is confusing me is the fact that both the balancer pulley and v-belt pulley wobble, even though the v-belt is bolted through the dampener center and therefore isn't "dampened".  Both seem to wobble in unison, which would suspect the crankshaft gear, but the wobble is irregular, which would suggest the gear is loose, which it isn't.  If it were the dampener, I would expect only that pulley to be effected, so I'm back to the crankshaft gear.  But since it's not loose, it would have to be askew, but that would lead to a more regular wobble, not the seemingly random wobble I have.  This is the third dampener that I have tried (all used) with no noticeable difference.


Any thoughts? 

Ian

[Wayland]

That looks pretty bad to me. Removing the lower timing sprocket is not a big deal, and the only way you'll know for sure what's going on.

[Quantum TD]

Well, pending your perspective, start on the cheap. While $70-90 for a new dampener is not cheap, it is cheaper an easier than replacing the motor, and quicker than pulling the crank go mill the nose for a TDI sprocket.

GEE BEE here had a thread about how he replaced the dampener (Harmonic balancer) and the crank bolt and it solved his wobble.

http://www.vwdiesel.net/forum/index.php?topic=26416.msg212561#msg212561

I would also suggest you replace the alternator pulley with the clutched-style, if you haven't already.

[Quantum TD]

Looking at your vid, that's pretty bad.

If the keyway on the crank nose looked OK, I'd say start with the new dampener.

It doesn't matter that the V-belt pulley is bolted to the crank sprocket, the wobble comes from the worn out rubber in the harmonic balancer.

[Wayland]

The V belt pulley is wobbling too, so I don't think a new damper is going to fix anything. A new crank bolt is only $5 or so, so why not remove the gear and inspect the crank. If it's screwed up it would be better to find out now than later.

[GEE-BEE]

Worn out dampner, new bolts also....

let us know...


Gee-Bee

[Henchman]

So are you saying that even with a tight bolt that there might be just enough movement, over 400k km and with possibly a failing balancer that the nose is now convex, if only a bit?  Interesting....  Wouldn't take much, and that would allow for a wobble.  And of course as soon as there is even the smallest of gap between the sprocket and crank, there is the possibility of corrosion, which could make the situation worse.  It wouldn't take much askew at the crank nose to look like a lot of movement at the pulley.

The reason I didn't pull the crankshaft sprocket was to keep things orderly.  I'm trying to isolate the problem, not just change everything and hope it fixes the problem because that often leads to unintended consequences!

What is a good source for balancers?  Mine is over $100, so I'm hoping for cheaper!

Ian

BTW, slightly off topic.  Did any of the AAZ end up with tdi sprockets later in production.  I pulled the sprocket off an engine that lost all coolant and cooked and it had the "d" revision sprocket and the crankshaft matched.  No sign on the crank that it had bee reworked....

Get the dampener if you feel good about that first.  It could fix it but very well might not.  If it doesn't, then pull the crank sprocket and inspect the keyway.  If the keyway is still in good shape, then pull the cam and have an assistant run the starter while you use a dremel with fiber reinforced cutoff wheel to true up the end of the crank.  Use the dremel with extreme care.  Run it so the wheel is almost parallel/planar with the face of the crank nose and favor cutting more from the center of the crank rather than the outside of it.  Favor making the crank face concave rather than convex.  You can also use a hand file afterward to see how it is.  If when run flat across the crank it cuts near the middle, then it is convex.  If it cuts at the two edges it is convex.  Replace the sprocket, set crank to TDC, install cam, yada, yada...

[Henchman]

First thing I did.  You can see the video links under the FAQ section or at my youtube site.

Thanks for the info!

I would also suggest you replace the alternator pulley with the clutched-style, if you haven't already.

[Mark(The Miser)UK]

Have you tried rubbing a piece of wood against the pulley when idling, to see if it will true up?

If not correctable, then have you considered that it might be a bent crank?
 [If that is possible of course ]
I'm guessing it's possible otherwise whats all that flat plate bolt on nappy/diaper stuff that one of my countrymen have been making eh?

[Henchman]

I think I may try this first.   Already did the new bolts to torque spec.  I was hopeful that blasting the replacement balancer would make a big difference because as you know the center is aluminium, and corrodes (well up here it does) and accumulates oxide in an uneven manner which I thought was taking the center out of balance.....  It was a theory.....

Worn out dampner, new bolts also....

let us know...


Gee-Bee

[Henchman]

If the pulley was bent or the crank was bent (which I suppose is possible, if not unlikely) I would expect the wobble to be regular in nature, certainly the v-belt pulley.  As it is irregular, it implies ongoing movement...

Ian

Have you tried rubbing a piece of wood against the pulley when idling, to see if it will true up?

If not correctable, then have you considered that it might be a bent crank?
 [If that is possible of course ]
I'm guessing it's possible otherwise whats all that flat plate bolt on nappy/diaper stuff that one of my countrymen have been making eh?

[Mark(The Miser)UK]

If the pulley was bent or the crank was bent (which I suppose is possible, if not unlikely) I would expect the wobble to be regular in nature, certainly the v-belt pulley.  As it is irregular, it implies ongoing movement...

Ian

Have you tried rubbing a piece of wood against the pulley when idling, to see if it will true up?

If not correctable, then have you considered that it might be a bent crank?
 [If that is possible of course ]
I'm guessing it's possible otherwise whats all that flat plate bolt on nappy/diaper stuff that one of my countrymen have been making eh?

How are you sure that it is irregular, as at idle the engine can be jumping all over the place; or at least it does on my mk2 Passat when strobed.
If you took a metal file and brought it towards the pulley until it scratched it, then you would see if it occurrs in several different places or just the one.
Can a crank actually flex at idle?
Probably only looking at microns in any case!
Can you spin the pulley in a lathe?

[theman53]

Could it be something like the thrust bearing is shot allowing in and out movement? I had an IM shaft that did just what yours did and it was IM bearings being trashed that caused it. They allowed the IM shaft in and out play as well as up and down, so it had an irregular pulley wobble and wanted to eat belts.
Not likely but possible

The other deal I would say is the dampening part of your pulley, but using 3 different ones I would guess that isn't it.

[Henchman]

As a matter of fact I can put it in a lathe!  What are you thinking, low rpm at fist to check for deformation and if that checks out, higher rpm to see if the problem is reproduced?

Ian

If the pulley was bent or the crank was bent (which I suppose is possible, if not unlikely) I would expect the wobble to be regular in nature, certainly the v-belt pulley.  As it is irregular, it implies ongoing movement...

Ian

Have you tried rubbing a piece of wood against the pulley when idling, to see if it will true up?

If not correctable, then have you considered that it might be a bent crank?
 [If that is possible of course ]
I'm guessing it's possible otherwise whats all that flat plate bolt on nappy/diaper stuff that one of my countrymen have been making eh?

How are you sure that it is irregular, as at idle the engine can be jumping all over the place; or at least it does on my mk2 Passat when strobed.
If you took a metal file and brought it towards the pulley until it scratched it, then you would see if it occurrs in several different places or just the one.
Can a crank actually flex at idle?
Probably only looking at microns in any case!
Can you spin the pulley in a lathe?

[Henchman]

FYI here is the thread about the clutched pulley install and before and after vids.  Did this before anything else.  You get another angle at the wobble.

http://www.vwdiesel.net/forum/index.php?topic=24517.msg225840#msg225840