AEL Zahnriemen gerissen. Nockenwelle viermal gebrochen! | Posts 16+

Hello,

I will definitely send a letter, whether it's filled with tears or written in a fit of rage.
The workshop probably can't do anything about the defect. It seems to be a material flaw. It's too thin, if you ask me.

By the way, the pictures are now visible! (Further above)

The tensioner pulley bears the original AUDI initials and part number.
It's made in CANADA. Not that I have anything against CANADA, but they really messed up here.
Even if you mean well and want to replace it at half the mileage, say at 60,000 km instead of 120,000 km, as I said, the bearing was already gone at 50,000 km. And I noticed that the needle bearing is even in five pieces.

I just built a special tool to hold the fan impeller in place. Without it, you can't reach the last screw on the timing chain cover/water pump. The engineers in Ingolstadt really designed it in a clever way!

Best regards, KAi.

Hi,

Unfortunately, I'm not very familiar with this engine, but I have a silly question: What is that rod on the left side, next to the break, where that NW part is sticking up? What does it drive? It looks almost as if this rod has split the NW part.
The damaged area appears to be a "clean tear" – smooth with no significant fraying. What's strange is that the ZR (presumably a component) doesn't seem to be missing any teeth.
Are there any signs of slippage on the teeth (if any teeth are still present)?
What was the rotational speed at the time of the crack?


... Slowly, things are starting to get really interesting...

Hello Bertil,

I could only review the entire service record yesterday. The large wheel on the vibration damper still had to be removed. Not a single tooth is missing.
Is the tension in the timing chain still high enough to cause teeth to break off, even after the chain has been loosened? You can clearly see the stretched section of the chain at the point where it broke. The break is not a fibrous tear, but a clean cut.

The RPM was below 2000/min, the engine was cold, and it had just started.

The plunger is connected to the vacuum pump. (That's why I asked the question earlier.) I don't think that's the cause. The nozzle is broken in two other places as well.

What is the likelihood that the pistons and connecting rods, which have been damaged, will need to be replaced? Are they fundamentally unusable, or can they be salvaged?
Connecting rods are only available in sets of five for €500.

By the end of the week, I think I'll be feeling down. Then things will get exciting again.

Best regards, KAi.
Okay, bitte gib mir den deutschen Text, den du übersetzt haben möchtest.
A6 Avant Quattro (C4) 103kw - five-valve engine.

kmrlange wrote:

The engine speed was below 2000 RPM, the engine was cold, and it had just started.

Okay, so you can assume that the belt immediately broke due to the blockage and that the teeth were not sheared off.

Quote:

The plunger is connected to the vacuum pump. (That's why I asked the question earlier.) I don't think that's the cause. The nozzle is broken in two other places as well.

Nothing is impossible.

Quote:

What is the likelihood that the pistons and connecting rods, which have been damaged, will need to be replaced? Are they fundamentally unusable, or can they be salvaged? Connecting rods are only available in sets of five for €500.

So, the probability that the valves have been damaged is 100%... You can see if the pistons have been affected when the head is removed; it's more difficult to check the connecting rods.

"On my brother's older car (a 2.1 D with 70 horsepower), the timing belt broke due to age (at over 200,000 km, just above idle speed), and we only replaced the cylinder head at the time. The engine eventually reached 400,000 km before another timing belt failure, this time caused by a frozen water pump, finally led us to decide it was time for repairs."
By the way, the head was completely ruined. The NW (Northwest) had torn the bearing surfaces out of the head, and it was also in five pieces. The crack in the timing cover didn't look like yours at all; it was very jagged and frayed.

Hi,

Here are the pictures of the broken ZR tensioner.


http://people.freenet.de/kmrlange/Spannrolle_Bruch.jpg


Here was the broken piece.
http://people.freenet.de/kmrlange/Spannr_zoom.JPG

Does anyone know if the impeller of the viscous fan drive really has a left-hand thread?
Even with a bribe, I wouldn't do it. There's absolutely no way I'm going to.

Best regards, KAi.

Hi,

Regarding the tension roller photos:
I'm not very familiar with that.
'But that broken piece isn't the part that attaches the pulley to the engine block, is it? To me, it looks more like the timing belt broke, and the force of the break caused the piece to snap off the tensioner pulley.'
-->The tensioner is broken. Specifically, the metal hook that secures the tensioner to the engine block. Apparently, the water pump was noticed to be worn out incidentally.


A worn-out water pump could also have caused damage to the timing belt.

Based on what I've heard so far, a head replacement is often sufficient for 5-cylinder engines.
You also wrote that it was running significantly below 2000 RPM.

Let's ask a different question (certainly not out of sensationalism - I drive a similar AAT myself).
What noises or side effects occurred when the belt broke?
Was it noisy? Is the engine blocked?
Or does it simply 'go out' and then continue on its way?

Hi,
It should be possible to determine at the fracture point whether it was a fatigue fracture or a brittle fracture.
I don't look my best in the photo.

Does anyone know if the impeller of the viscous fan drive really has a left-hand thread?


It could very well be, depending on the direction of rotation. If the motor (as viewed from the motor itself) rotates counter-clockwise, then it must be a left-hand thread .

From memory, I can't think of any car engine that (referring to the shaft) rotated counter-clockwise. So, if you're standing in front of the engine and it's rotating clockwise, there's a left-hand thread inside... well, are you confused?

btw: Where does this spool come from? It looks pretty bad for an original part. Is it a counterfeit?

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

'Cu Gremlin'

Gremlin wrote:

I can't recall any car engines from memory that rotated counter-clockwise (with respect to the shaft). Cu Gremlin

Ancient Fiesta engine.

Hello there,

This broken hook on the tensioner pulley releases the timing belt tension when it breaks.
Then the tension is lost from the belt, and slippage can occur.
Regarding the cursed Visco fan: The motor is already rotating clockwise (when viewed from...).
It's positioned in front of that. However, the fan blade rotates clockwise. Therefore, a left-hand thread makes sense.
I still can't get it open. I probably have to remove the entire generator carrier because of...
a WP screw.

Yesterday, I took the head off. Everyone should try doing that on their car sometime.

The pistons all look like fresh springtime. No deposits, no...
Damage. I was almost a little disappointed.
Anhand der Betrachtung der Kolbenböden läßt sich nicht feststellen welcher Kolben angeschlagen hat. InInteresting!!

http://people.freenet.de/kmrlange/Kolben_boeden.jpg

http://people.freenet.de/kmrlange/Kolben_2.JPG

And now here's the thing: If you look at the underside of the cylinder head from the valve seat side, you see absolutely nothing!!
Not even the smallest scratch on any of the valve discs. They are all perfectly aligned, and none of them appear damaged.
I didn't take any pictures at all.

But when I completely removed the NW, it came to light.
The fifth piston has damaged both hydraulic lifters. Both were approximately 4mm deeper in their respective bores.
Drilling: Different from the rest.

http://people.freenet.de/kmrlange/Hydrost_Zyl_5_defect.JPG

http://people.freenet.de/kmrlange/Hydrost_Zyl_5_defect2.JPG

Based on the damage to the fifth cylinder, it makes sense to at least do this.
Replacing the connecting rods. What do the professional mechanics recommend? Should the pistons also be replaced?
Are you talking about connecting rods, because they're only sold as a set?

Best regards, KAi.

Bitte gib mir den deutschen Text, den du übersetzt haben möchtest.
A6 Avant Quattro TDI 2.5 AEL

kmrlange wrote:

Based on the damage to the fifth cylinder, it makes sense to at least do this. Replacing the connecting rods. What do the professional mechanics recommend? Should the pistons also be replaced? Are you talking about connecting rods, because they're only sold as a set?

Hi,

The engine looks really good.
Should I replace the connecting rod or not...? I would measure to see if the piston is lower than the others when it's at top dead center. It's especially important to compare it to the other pistons. While it's possible that the connecting rod is bent, you can only determine this by measuring (which unfortunately isn't very precise) without disassembling everything and then reassembling it.

If you're lucky, the NW (presumably a component or system) failed faster than the underlying structure, which is what happened.

EDIT:

Die beschädigten Hydros sitzen fest? Or what?
There's a possibility that a valve spring broke (among the defective hydraulic components), causing a valve to close too late or not at all, which then forced the piston against the cylinder head, also damaging the timing chain. The tooth on the tensioner pulley also broke due to the "overextension" of the timing chain. While the water pump could be worn, it might also have become jammed due to this damage and ultimately failed completely.

Now, imagine you had a chain... it wouldn't travel as fast, and the damage would have been much greater (to all you ZR haters ).

Hello Bertil,

The Hydros are loose. I've already had them outside. I have one right here. As mentioned before, all the valves are properly closed. I can check if any of them can be pressed down slightly.

Considering the relatively minor head injuries, aside from the neurological issues.
A head overhaul, is it worth considering?

Best regards, Kai.

Hi,
Could you please post some photos of the fracture points on the tensioner?

kmrlange wrote:

Given the relatively minor damage to the head, excluding any issues from the Northwest, would an overhaul of the head potentially be worthwhile?

Okay, the bearings for the NW (presumably a machine or component) are located in the head, and it's difficult to determine if they have sustained any damage. If the bearings are okay, you could consider an overhaul, but I wouldn't recommend it.
Can all the valves still be moved?
That would be surprising, as I had assumed there was a compression of the valve stems, which would mean the valves were pressed tightly into the cylinder head. Therefore, the NW (presumably a component or process) prevented something worse from happening.

kmrlange wrote:

Hello Bertil, The Hydros are loose. I've already had them outside. I have one right here. As mentioned, all the valves are properly closed. I can check if any of them can be pressed down slightly.

Have you ever completely flushed all the valves before? I mean, the cam is already out.
Turn the head so that the valves are at the top, then carefully pour a small amount of diesel into each one and observe.
Whether it remains standing or slowly leaks out. Bent cables aren't always visible, but they are sometimes.
For safety's sake, I would definitely replace the damaged ones; it's only a few euros, and it will make things right.
not significantly more expensive.

Regarding the piston itself... Well, I don't know how it is with that particular car, but at Opel, we used to have...
they were always getting beaten badly, and the team's morale was suffering.
The motor then started making a loud clattering noise.

Here's the translation:

"What you can do is turn the piston to its top dead center position and then a hair's breadth beyond that. When you press down on the piston, it shouldn't move further. You can also try accessing it from below."
Grip the piston and try to push it up and down on the crankshaft; this should not be possible.

Hi,

'No, I haven't removed the valves yet. But let's say someone is restoring something...'
head. I definitely need a new NW anyway. It probably won't stick.
Then, at a minimum, two new valves and valve lifters. Also, all the valves and their seats need to be replaced.
'Measuring is also mandatory. I haven't looked into it further yet, but I think...'
That's about the same price as a replacement head. Does anyone know how much a new NW costs?
Without any exchange, because I already have five small ones.

Regarding the piston: You probably mean the connecting rod bearing in the piston, which is located on the 'ears.'
or both? I'll try to measure the overhang.


Here are the pictures of the broken tensioner. Unfortunately, I don't have a microphone .
But I've taken everything out of the Didicam.

http://people.freenet.de/kmrlange/Halter_bruch.JPG
http://people.freenet.de/kmrlange/Halter_bruch2.JPG

http://people.freenet.de/kmrlange/Rolle_bruch.JPG

Do the images tell us anything about the fracture process? I'm curious.
Best regards, Kai.