Crankshaft Screw Replacement for AAZ Engine

Hi,

Today, I replaced the crankshaft bolt on the AAZ engine as part of the timing belt replacement (the original bolt was still in place). The old bolt came out relatively easily (hopefully, the bolt wasn't already loose )... but installing the new 12.9 bolt made me sweat more than I have in a long time while working on cars . With a 3/4-inch breaker bar, I could only achieve the required torque (90 Nm plus 90°) with my feet . Without the VW tool 3099, this job would definitely not be possible .

I have another idea for the problems with the crankshaft bolt:
If you look at the vibration damper more closely, it consists of parts that are separated by a rubber ring (similar to the tires on an ICE train, I'm not sure if the damper on the 1Z, AFN, etc. is constructed in the same way). If this rubber becomes brittle over time, it is quite conceivable that even the new screw will not hold due to the movement of the engine .

What do you mean? Can we say that, for example, after 180,000 km, it makes sense to simply replace the shock absorber as a preventative measure ?

haehnlein wrote:

With a 3/4-inch lever, I could only manage the turning angle (90 Nm plus 90°) using my feet, despite strength training . Without the VW tool 3099, this job would definitely not be possible

.

Hi Christian,

If the VW part offers a longer lever than 3/4" = approximately 19 mm, it is certainly a huge improvement .

Quote:

If this rubber becomes brittle over time, it is quite conceivable that even the new screw will not hold due to movements of the eggs

.

Hmm? Does the KW screw somehow compress the rubber?
Or do you think the damper might become unbalanced and therefore start to vibrate loose?

ulf wrote:

If the VW part offers a longer lever than 3/4" = approximately 19 mm, it will definitely be a huge improvement

.

Hi Ulf,

I expressed myself incorrectly . The VW tool is just a counter-holder to prevent the crankshaft from twisting! I meant a Hazet assembly lever, 3/4" size, with a length of 500 mm. If you already have to use your feet to operate it, then considerable force is required!

Quote:

Hmm? Does the KW screw somehow compress the rubber? Or do you mean that the damper becomes unbalanced and therefore shakes loose?

Okay, so: the pulley for the ribbed belt (=vibration damper) consists of two parts that are separated by a rubber insert (similar to a rubber-metal bushing) (the pulley for the ribbed belt is mounted on top). Both are mounted on the crankshaft pulley and are secured with four Allen screws. If the rubber becomes brittle over time, it is conceivable that the resulting vibrations could loosen the crankshaft screw, with the known consequences . However, I don't currently know if this vibration damper is constructed in a similar way on the TDI (I've never paid attention)...but I think it is .

haehnlein wrote:

The pulley for the ribbed V-belt (also known as a vibration damper) consists of two parts that are separated by a rubber insert (similar to a rubber-metal bushing) (the pulley for the V-belt is mounted on top). Both are mounted on the crankshaft pulley and are secured with four Allen screws.

Hi Christian,

That's, as far as I know, the same principle as in TDI engines (at least in VP engines).

Quote:

If the rubber becomes brittle over time, it is conceivable that the resulting vibrations could loosen the KW screw, with the known consequences

.

So, you mean when the damper starts to feel "loose" or "mushy" internally?
Hm... Strong oscillations can only occur if the system builds up energy (resonance), and that, in turn, depends on the ratio of the possible energy storage capacity and the constant (internal) frictional losses.

In the field of electrical engineering, I understand the basic principles behind LCR resonant circuits.

Regarding vibration dampers, I don't believe that rubber becoming brittle necessarily means that it has a fundamentally lower energy absorption capacity than new material.

Another point, of course, is the spring constant of the material. This also influences the system's susceptibility to resonance: if the rubber deteriorates, pronounced resonances are more likely to occur.

Quote:

I'm not sure right now whether this vibration damper is constructed in a similar way in the TDI (I've never paid attention to it)...but I think it is

.

Even in my opinion, the basic principle is likely the same - why reinvent the wheel with a TDI?

ulf wrote:

So, you mean when the damper becomes "sloppy" internally? Hm... Strong oscillations can only occur if the system builds up energy (resonance), and that, in turn, depends on the ratio of the possible energy storage capacity and the constant (internal) frictional losses. In the field of electrical engineering, I understand the basic principles behind LCR resonant circuits. Regarding vibration dampers, I don't believe that rubber becoming brittle necessarily means that it has a fundamentally lower energy absorption capacity than new material. Another point, of course, is the material's spring constant. This also affects the system's susceptibility to resonance: if the rubber deteriorates, pronounced resonances are more likely to occur.

Hi Ulf,

In a similar vein (though not quite as precise), that's what I also thought. My primary goal is to figure out the cause of the KW screw defects. There have been several cases in the forum where the new screw also failed. If the screw is tightened correctly, nothing should actually come loose in that area , at least I can't imagine that happening given the enormous force required to tighten it. But maybe it's the fault of insufficiently trained mechanics? The cause of the problems can only be due to incorrect screw installation or the aforementioned vibration damper . I seem to recall reading that the mass distribution in the vibration damper is inhomogeneous (as a "counterweight" to the flywheel)... perhaps that leads to sufficient vibrations . Well, we'll figure it out eventually .

Hi Ulf,

....and one more thing: if I remember correctly, you haven't put that many kilometers on it yet . Please, during your next maintenance, check the vibration damper (ideally from below) with the engine running. Does it run perfectly straight, or does it wobble a bit ? In my friend's AAZ (96,000 km), the pulley already wobbles quite a bit...more than in my 1Z with 180,000 km. Thank you in advance .

Hi,

The vibration damper on my Passat 35i Variant 1.9 TD (AAZ) from '92 is wobbling.
(I've only had the car for three weeks. The replacement engine has only been driven about 45,000 km - something probably happened during the installation...)
'Now I'm searching for a suitable replacement part at junkyards. The VW part number is 028 105 243 T. According to a VW dealer, this vibration damper is also used in the Audi A 6 1.9 TDI with 66 kW (1Z) from 1996-97, in the Audi 80/90 (1992-96), in the Audi Cabrio (1992-2000), in the Caddy (1996-2003), Golf (1992-9, Passat (1988-97), Polo (1996-2000), Transporter (1991-2004), and Jetta/Vento (1992-9.'

Do you know anyone who sells this type of vibration damper for less than Volkswagen?
(They want 250 euros!)

What does the 'VW tool 3099' look like, and where can I get it?

Greetings from the Huber family...

Edit dieselmartin: (1998) to 1998) - to prevent any smileys from appearing

VW 3099 is used to lock the crankshaft.

Google has found Stefan's/Steffen's (?) guide on how to install kilowatt-hour meters again!

http://home.arcor.de/sgrafen/salatoel/kw_schraube/kw_schraube.html

Hi Huber,

You only need tool 3099 if you want to loosen the KW screw. For the shock absorber, you only need an Allen key (size 6, for the four screws).

Hello,

and thank you very much for the information.
I'll then continue searching the junkyards...

Regards,
Christoph.