Crankshaft pulley wobble, 94 Jetta TD

[Kneale Brownson]

I was just checking under the hood to try to figure out why my A/C isn't cooling--looking to see that the fans turn on when the A/C switch is pushed, etc., and I was looking at the ribbed belt, watching it turn the compressor, when I noticed that there is an easily observed wobble to the rim of the crankshaft pulley.

Is that a concern?  Should I be attempting to tighten the crankshaft bolt or anything?  Or is it time to replace the belt and get everything right?  The car's records (it's new to me) show the belt was done a couple years ago at a VW shop and it's not gone anything like 60k miles since.

[bigblockchev]

do a search for "crankshaft pully wobble"
This happens on the AAZ motor. There is much to learn. Cheers Dan

[Vincent Waldon]

To answer your initial question:  "YES... this is a concern" !!  If it's what we think it is the crankshaft keyway and/or key are worn... when it finally snaps the pistons and the valves will intersect with a loud and potentially expensive noise.

There's lots of discussion here on what it is and what needs to be done, but I would recommend it be investigated at your earliest convenience.


Vince

[Kneale Brownson]

Thanks, guys.  

I'm going to get the car on my hoist and check out the fasteners for the pulley.  

The service records I have include the last two timing belts, one late in 05 and the other several years earlier.  Neither includes a charge for the crankshaft bolt.  

I take it from the description of belt change in the Bentley that it's not necessary to remove the crankshaft bolt.  Is my interpretation correct?

[Vincent Waldon]

Yup, no reason to touch the crankshaft bolt to do the timing belt... in fact, you tend to want to leave it alone since it's a stretch bolt and needs to be replaced if it is loosened.

Let us know what you find when you pull the bolt and pulley... fingers crossed it's not the usual mangled keyway !!!


Vince

[commuter boy]

The original bolt was upgraded to the TDI style one, which has a dimple standing out in the middle of it.

You can feel if it's the new bolt by just touching it with your finger.

I don't know if it should be upgraded or not, perhaps wiser heads will advise.

[Kneale Brownson]

I won't be able to get to it for a couple days.  The hoist is covered with lumber I'm painting to use as trim for a roofing job I have to do on a rental.

[jari_veedub]

I was out of town with my 93 golf a few yrs back and noticed a wobble in my crankshaft pulley too.  I figured it will last until I get home and in the shop.   I was only a few km's from home when the bolt broke, hence the timing belt came off and I blew the engine.  This happened at over 100km/hr.  Toasted the engine.  
Hopefully you'll get it repaired, and yes do let us know what ya find.
:)

[Kneale Brownson]

The outer edge of the ribbed belt pulley (arrow) wobbles, as does the smaller pulley for the water and power steering pumps.



Is the bolt in the center the newer "dimpled" TDI version?  

All four of the smaller pulley bolts are very tight.

So I presume now I need to basically do a timing belt replacement to get down to the point I can check the keyway?  Or will I be able to do that with just the outer pulley removed?

Is there supposed to be a cover over this part of the engine assembly?

[bigblockchev]

1 Yes  the bolt actually preceeds TDI but it is the good one
2Yes
3 yes no
4 No
You will have to remove the front v-belt pully and serpentine pully to get to the timing belt toothed pully. The centre bolt with the tit on the end is 19mm 12pt and will probably be really  really tight.  If you get this far you will probably want to replace it in any case. Which is a good thing as it is difficult to get a wrench on it without damaging the teeth. The end of the crankshaft with the keyway usually ends up wearing on the outer edge as well as the keyway. This wear is what causes the wobble, so the front of the crank needs to be squared off in the process of repair. See the pics here http://www.vwdiesel.net/phpBB/viewtopic.php?t=2771&highlight=crank
You should also replace the ribbed pully(harmonic damper) with the new style same part # as old one but with aluminum outer rim. All this is pretty much just for the sake of information as chances are that your keyway and crank nose are worn. It happens to all of the AAZ motors just a matter of when , not the end of the world but a lot of work to fix. A number of the vendors on this forum can help you with crank repair. Cheers Dan

[Kneale Brownson]

Thanks, Dan.

I had shuddered my way through your report in the link earlier in response to other replies that I should look on the forum.

So, even if my damage isn't as bad as what your photos show, it eventually will get that way?  Guess I'll just have to strip it down and see.

Is there some tool for keeping the crank from turning like the Audi crank holders?  Does the  2065A tool shown in the Bentley to hold the camshaft  do that job?  Of course, the Audi crank bolts are 350 ft lb., not  66 ft. lb + a quarter turn.

What part numbers do I want for the new bolt, damper pulley, etc.?

[MikkiJayne]

I had exactly the same problem on my AHU. At some point the bolt has worked loose, allowing the sprocket to bash up the end of the crank. Rather than fix it the PO just put it back together  

I tried filing the end of the crank flat (measuring with verniers), putting it all back together and spinning on the starter. I tried 12 cycles of this (in a day) and got nowhere. Eventually had to take the crank out to get it faced up properly on a lathe. They mended the keyway too, for £35, but in taking it to bits I discovered that all the bearings (rods and mains) were shot, in what was sold to me as an 80k miles engine  :evil:

So all in it's costing about £200 to fix, with machining, bearings, gaskets etc. I get the crank back next week.

Good luck, Mikki x

[bigblockchev]

Kneale the pix in the post are not mine.  I benefited from Quicktd's info when I recently had to do the same job on my engine. I am not aware of a tool to hold the crank, my understanding is that some guys pull the oil pan and wedge the crank journals with a 2x4 or some such thing. The torque on the bolt at 66Ft lbs + 1/4 turn is quite a bit. My torque wrench goes way the hell up when doing the 1/4 turn , wouldn't be surprised if it is in the same range as the Audi ultimately.
Mikki it is sometimes a shock to find things like this but the alternative is worse. Can be major damage if it causes the timing belt to jump and damage the head. Cheers Dan

[commuter boy]

An impact gun will get the crank bolt off, but to put it on you will need to counterhold it somehow.

I've used a prybar jammed into the timing hole into a flywheel tooth along with the car in gear with the brakes on to hold it.  And a big ass breaker bar with a long steel pipe extension.

Anyone tried one of these Metalnerd tools?

http://www.metalnerd.com/images/products/cat05/mnyankp.jpg

[MikkiJayne]

That's similar to the tool I've made for mine.

I used a piece of 1.5" right angle bar, and cut out a hole for the center of the sprocket, and 3 of the bolt holes in the pulley. I use the water pump pulley socket-head bolts to hold the bar on to the sprocket. Rotate the crank until the bar hits something (subframe for me), and then take the bolt out with a long breaker bar, and a 19mm double-hex socket.

I'd have preferred to make something that had all four bolt holes in it, but that would have been harder to do, and I didn't have any material spare to do it. 3 bolts seems to be enough though.

No pics cos my engine is in bits and it's raining out, but if anyone really wants to see I could go get a couple.

Mikki x