Timing Belt Replacement: 1Z Model Questions

Hello.

I have a question about the timing belt replacement for an Audi 80 B4 TDI with a 1Z engine!

Yesterday, I took my car to my trusted mechanic, the same one who replaced my timing belt before, because it's been having cold-start problems.

'First, they determined the injection timing, which was significantly outside the normal range! Then, they tried to adjust the injection timing, but unfortunately, the adjustment range of the injection pump was not sufficient. Therefore, the master technician was called in, and he immediately noticed that the pulleys, on which the V-belts for the power steering pump, water pump, and alternator run, were slightly 'wobbly'! The timing belt also runs on the same shaft (i.e., the crankshaft). This pulley was also wobbly, which is why the injection timing was so misaligned.'

So, I should leave the car there to eliminate the risk that the screw might come completely loose and damage the engine. He also wanted to perform the repair for free, since that screw had to be opened during the timing belt replacement!

So far, so good!

When I called him today, he said that he had been mistaken and that the screw didn't actually need to be opened to change the timing belt, and that I would have to pay for the repair myself.

And now, to my actual question:

Who knows if the described bolt really doesn't need to be opened for the timing belt replacement? Or can the bolt be opened, making the process easier? Or is there another reason why the bolt might have been opened?

P.S.: He also said that this screw sometimes opens on its own with the 1Z engine, which is a known issue with that engine that occurs occasionally.

I am grateful for any answers!

Best regards,

Sure, here is the translation of the text from German to English:

'Didl' is a German word that means 'a small, round object.' It can be used to refer to a variety of things, such as a ball, a marble, or a button.

didl wrote:

Who knows if the described screw, which is supposed to be used for the timing belt replacement, really doesn't need to be opened? Or can the screw be opened, making the process easier? Or is there another reason why the screw might have been opened?

Hi Didl,

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

It looks like the KW screw is loose... If this was replaced by VW, as described in the link, you might be able to negotiate a warranty claim with some luck; otherwise, it will be expensive because the KW stub needs to be re-machined . Do not drive the car anymore, otherwise the engine will be damaged .

Please check if the 12.9-grade screw (see link) is already installed!

Best regards, Christian.

Since you drive an AUDI 80, I assume you've put quite a few miles on it. After a long period of engine operation, I find it impossible for the screw to simply come loose on its own.


Case 1:

The workshop replaced the pulley on the crankshaft, but then didn't tighten the screw properly.


Case 2:

The V-belt and ribbed pulley definitely need to be removed. Perhaps these 4 screws weren't tightened properly, which is why the belts aren't running correctly. However, that doesn't explain the starting problems. It's possible that the timing belt was simply replaced, and the timing sprocket wasn't realigned.

Diesel-Dirk wrote:

Since you drive an AUDI 80, I assume you've already put quite a few kilometers on the odometer. After a longer period of engine operation, I find it impossible for the screw to come loose on its own.

Hi Dirk,

I am aware of three cases from the forum where even the NEW screw broke after over 100,000 km (either overtightened or undertightened) . JanB even had a case where the crankshaft broke a long time after the replacement.........but you are right about the four screws!

The sudden appearance of these problems strongly suggests that the KW screw is the problem. The timing belt usually doesn't stretch so much that the adjustment range of the pump would no longer be sufficient (or the timing was not set correctly, which, however, would have caused the problem all along) .

@Didl:

Let us know what the results are!

Best regards, Christian.

Hello.

Thank you for the answers!

Unfortunately, I had a bit of bad luck with the goodwill gesture... or perhaps it's good luck in disguise, depending on how you look at it... if this had happened in the summer, the engine would probably be completely broken, as there likely wouldn't have been any starting problems then!


The 12.8mm screw was installed, but it was probably already replaced during the first timing belt change, which my workshop didn't perform because I didn't own the car at that time.


The timing belt pulley's locating tab was already quite bent and would probably have broken completely soon.


And finally, one more question: What torque should be used when tightening the KW screw?
90 nautical miles plus 90 degrees, or approximately 200 nautical miles?


Best regards,

Sure, here is the translation of the text from German to English:

'Didl' is a German word that means 'a small, round object.' It can be used to refer to a variety of things, such as a ball, a marble, or a button.

didl wrote:

The timing belt pulley's locating pin was already quite bent and would probably break completely soon.

Hi Didl,

Try to describe more precisely what was bent! What do you mean by "guide pin"? Are you referring to the 3mm protrusion on the KW wheel?

Was ist die Übersetzung von "Wurde die Kurbelwelle nachgeschliffen?" ins Englische?

didl wrote:

And finally, one more question: What torque should the KW screw be tightened to? 90 NM + 90° or something around 200 NM?

The information on this page is partially incorrect.

Tightening torque for 1Z, AFN, AAZ engines: 90 Nm plus 90 degrees (source: VW repair manual).


Best regards, Christian.

Hello haehnlein,

To which vehicle and model year do your specifications refer? Usually, the tightening torque is:

1. Level 40 Nm.
2. Level 60 Nm.
3. Level 90°.
4. Level 90° (as mentioned above)

Hi Michael,

I actually wrote this here: https://community.dieselschrauber.org/en/viewtopic.php?t=2182
Sometimes, the text seems to drift or become unclear.

This refers to the tightening torques for the cylinder head bolts on the 1Z, AAZ, and AFN engines. The crankshaft bolt must be tightened to 90 Nm plus 90 degrees, using the same torque wrench settings.

Best regards, Christian.

By the way, the Erwin (siehe Fehlerdatenbank) manual states that the threads and collar of the KW screw must be free of oil and grease . In the old mechanic's books, it mentions lubricating the threads . Perhaps this explains the causes of the problems with the new 12.9 screws . It's possible that some workshops don't know that these screws are now apparently used without oil .

Best regards, Christian.

@haenlein

Yes, that's the survey I'm talking about!

The crankshaft was reground (machined).

Hi Didl,

It's possible that the four Allen screws weren't tightened enough (or were stripped?) and that's why the new 12.9 screws also came loose (due to the vibration of the shock absorber). At the very least, you could blame the workshop that performed the last timing belt replacement. It might be difficult to prove, but it's not impossible! Did you have to pay for everything yourself?

Best regards, Christian.

Yes, unfortunately, I have to pay for everything.