Crankshaft Screw TDI

Hello friends! With which engine codes might there be problems with the aforementioned screw?
Best regards,
Holger

atzleh wrote:

Hello friends! With which engine codes can there be problems with the aforementioned screw? Best regards, Holger

Generally, with any engine.

However, the situation is particularly problematic with the AAZ and the early 1Z engines. A modified connecting rod bolt was also introduced for these engines.

Even within the AFN, cases have become known through the forum .

Best regards, Christian.

Keep an eye out for AEL and AAT as well.

Regards,
Wool

I also heard from a VW master technician that most cases occur with the AFN engine and even more frequently with the 1Z engine.

IF a 1-ton truck (=ABP; =AAT without catalytic converter) fails, it's either due to an accident or a broken crankshaft at the specified location, caused by the aforementioned screw.

Best regards, Björn.

Hi Bernhard,

Do you know (or does anyone else), whether the harder screw is now also used during timing belt replacement in AAT engines, as part of the constantly updated inspection guidelines?
Someone mentioned in this forum before about a screw with higher strength.

Yes, actually. I already had the fixed one installed, and I replaced it with a new one during the change. I don't have the specifications memorized, but I took a picture of the screw head. Some workshops really mess things up. Just recently, my brother's 1.9L TD (without intercooler) had a major issue because the screw completely came loose. The workshop apparently didn't tighten it enough. In my opinion, the screw shouldn't be tightened with oil, as described in the Audi repair manual, but without oil, using a torque wrench, with a holding tool, at 500 Nm, and with plenty of Loctite. I've done it twice already, and I haven't had any problems with 277,000 km on the clock. Hopefully, I won't find a piece of the crankshaft falling out during the next change...

Best regards, Björn.

boernhard wrote:

In my opinion, the screw should not be tightened with oil, as described in the Audi repair manual, but without oil, using a torque wrench, with a holding fixture, to 500 Nm, and with plenty of Loctite.

Hi Björn,

500 Nm is too much. You risk a crankshaft fracture with that. The repair manual for AAZ, 1Z, and AFN engines states that you should NOT use any oil. Thread locker is definitely useful. The torque is 90 Nm plus 90 degrees for the mentioned engine codes (for other engine codes?). That should be followed. If the stub is damaged, you should grind the crankshaft flush beforehand, because even excessive tightening won't help in case of damage.

Here's another interesting link about it:

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

Best regards, Christian.

Hello Christian,

So, nochmal die Kurzfassung, ich hatte einen langen Text geschrieben und mein Browser wollte nicht. Cry.

My comment was an indirect response to a previous comment I made, which mentioned that it concerns the 1T engine (the original TDI = Audi 100 TDI, manufactured in 1990, 2.5 liters).

It actually mentions something about oil in the REP guideline.
And both the guide and the Etzold manual ('How it's done') state:

1. Torque with Audi-specific extension. 350 Nm (this has a specific lever ratio).
2. Torque: 450 Nm (using a standard wrench).

Problem: If the screw is not tightened sufficiently, the connection becomes loose, and the spline (not 'coil spring,' but 'spline') of the gear can damage the crankshaft spline. If the screw is tightened too much, the crankshaft can break, as you mentioned.

So, who knows the patent solution?
I, for one, use a lot of torque and Loctite.

Best regards, Björn.