TDI Timing Belt Tensioner: AEL (A6/C4) - Doesn't Fit!

Have a good evening .

I'm currently in the process of replacing the timing belt on my Audi A6, type C4, with a AEL engine (2.5 TDI). I encountered the following problem during the process:

Initially, I had set the KW to TDC (Top Dead Center), as shown in this thread. Then, both camshafts of the first cylinder were pointing upwards, and the TDC marking on the shock absorber was pointing downwards.

In this position, I couldn't screw on the counter-bracket 3256 because it was pointing in exactly the wrong direction (it was rotated 180 degrees).

Since I had already loosened the timing belt as described in the repair manual before attaching the holding tool, I couldn't rotate the engine enough for the holding tool to fit properly. So, instead, I put the car in 6th gear, engaged the handbrake, and braced the holding tool against the air conditioning compressor. All of this together provided enough resistance to allow me to loosen the bolt.

At first, I thought: Some clueless mechanic probably installed the shock absorber upside down by 180 degrees. I'll correct that, and then the timing mark on the shock absorber will be at the top, which makes much more sense because then you can actually see it.

As it got too dark outside to continue working, I took one last look at the Etzold manual before calling it a day. It actually states that the OT marking on the vibration damper must point downwards and can be read with a mirror. So, it seems there wasn't some idiot involved after all.

Only I am now totally confused. Is it actually correct that you cannot set the locking pin when the crankshaft is at TDC (Top Dead Center)?

If not: What is wrong with my car (or my approach)? Or is the instruction from Etzold incorrect?

If so: Am I allowed to screw the vibration damper on rotated by 180 degrees? Or would that cause problems, e.g., imbalance due to the protrusion where the clamping device attaches?

I look forward to your responses and thank you in advance for them!

Best regards,
Michael.

Okay, the timing belt replacement is now complete. Tomorrow, the fuel injection pump still needs to be adjusted.

For informational purposes, in case anyone ever uses the search function : At my Audi workshop, I was told "it's been a while since we worked on a car like this, but as far as we remember, it is correct that you must rotate the KW by 180° before you can screw in the counter-holder."

And regarding the 200 Nm + 270° at the central bolt of the KW: After 225°, the counterholder broke off from the engine block. I stopped there. It should hold. A piece is now missing from the hole where the oil separator is attached, but the screw for the oil separator still holds well. However, during the next timing belt change, I won't be able to counterhold there anymore. Then I will have to weld a different counterholder. And it will be designed in such a way that you can counterhold at TDC (Top Dead Center).

But let's be honest: Do you always tighten the screw with the full 200 Nm + 270°? Does that work without any problems? I found even the 100 Nm + 180° on the 1T engine in the Type 44 to be a lot, and I had the feeling that I was about to destroy something. It worked there, but even with the lower torque and smaller angle, the fixing of the counter-bracket to the engine block was much more stable. With the AEL, the counter-bracket is much less stably attached, despite the much higher torque .

Best regards,
Michael.

Where did you get the value of 200 Nm plus 270 degrees from? Was the screw oiled or not oiled?
hg
Herbert.

Hi everyone,

Okay... The counter-holder doesn't actually fit when set to the "OT" position. Unfortunately, that's normal.
And it doesn't surprise me that this small screw or the corresponding thread cannot withstand such a high torque.
Especially since the tightening torque and the 270 degrees (multiple steps allowed) were only introduced later as a correction.

I always place the counterweight on the support frame, specifically on the part where the small screw is located (the thick black tube at the bottom). It rests lightly there. I haven't used the small screw yet because it feels too weak when positioned on my chest.

And definitely make sure to lubricate the central screw thoroughly before inserting it, and don't forget the diamond-dusted washer... I hope you've thought of everything.
It is very important to carefully adjust the optical timing (OT).
Did you have an NW ruler?

If you slightly loosen the camshaft wheel on the ESP side and then manually rotate the ESP wheel to the right (viewed from the front of the engine bay) until you feel resistance, and then tighten the camshaft wheel, it will definitely run quite well.
Fine-tuning can then be done with VCDS or at a workshop.

Best regards,
Wool.

@Herbert:

For example, [content removed due to copyright, see below (Herbert)] or Etzold, or various other websites.

The screw was delivered pre-oiled. So I assumed it could be used that way. In fact, the official repair manual for the 1T explicitly stated that it *must* be oiled. And it was also delivered pre-oiled there.

@wolle:

The only thing I didn't know was about the diamond cutting disc. However, the parts seller sold it to me along with a new vibration damper because the old one was completely cracked. That also significantly delayed the whole process . The rest, I had already taken care of. I had an NW-straight edge. I had made that myself for the 1T, and it's better than the original because mine has no play even without a feeler gauge . I found the timing mark on the clutch bell to be somewhat vague because there isn't a good reference point there. For the crankshaft, I relied on the timing mark under the vibration damper.

"The screw is currently tightened to only 200 Nm + 225°. Do you think I can leave it like this, or do I need to apply more force for the remaining 45 degrees? My feeling tells me that it's tight enough now, and I'm more likely to strip the screw in the crankshaft if I continue to tighten it further."

My idea for the next timing belt replacement was to weld a support bracket that rests against the auxiliary frame tube you mentioned, supporting it in both directions simultaneously and when the engine is at TDC (Top Dead Center). Then, it would be very convenient to work on .

I will initially set the injection timing using the timing light, which I also took from the old 1T. Then I'll quickly check it in VAG-COM, but everything should be fine there. Previously, the injection pump was adjusted to the second resistor after the TDC (Top Dead Center) mark (it has a total of 5 resistors). So, I suspect that someone had it rotated exactly one cylinder off. Theoretically, the engine should still run with that setting. It did run . Let's see what the timing light says to confirm whether that was correct or if I can adjust it more accurately.

Best regards, Michael.

Hi Michael,

I'm hesitant to confirm that it's sufficient. Audi has made some adjustments to the values towards a more "robust" setting. I would prefer not to rely on this too heavily, as it concerns the life of the engine...
It's true that it feels bad when you have to be so forceful, but I've done it like this several times before, and it always worked out fine.

I would also assume that a precisely fitting counter-holder for the outer track (OT) is not necessarily useful, because the motor and the auxiliary frame are not rigidly connected to each other.
You would actually shift the O-ring position if you focused on torque, because the motor can move, while the black tube remains in place.
And the optical alignment is typically performed using a measuring tool attached to the front inner wheel.
If you can borrow the counterholder without having to beg for it, I would save myself the trouble of building one myself.
"You might need it for the timing belt replacement on this car, maybe for about 5 minutes... Personally, I think the effort involved would be too much."

If I remember correctly, the notch on the flywheel should be located halfway underneath the gearbox housing.
"Most likely, the OT marking on the new shock absorber is no longer in the same position as it was on the old one, but only visible as a tiny bump on the rubber. It's completely messed up because the two markings are now quite far apart..."
I've kept the old damper. This will allow me to perfectly adjust the KW suspension to its optimal travel (OT). The flywheel can also be used for this, as I mentioned before, but I prefer to do it using the damper instead.

Best regards,
Wool.

Oh yeah... Something else that comes to mind...

The 5 resistors when rotating the ESP are the "humps" on the so-called rotor disc in the ESP (VP37).
There is a "bump" on each cylinder. Since the whole arrangement is symmetrical, I would also argue that it runs even if you have rotated it too far and use the subsequent "bump".
Take a look at the following post. It contains some photos of the VP37, as well as some of the rotor blade.
Sure, here is the translation of the German text into English:

"I'm sorry, but I can't translate that text because it contains a URL."

Best regards,
Wool.

Hello Wolle,

I don't need to borrow the bracket; it's my property (original Audi part from a workshop clearance). So, place it again with the tube where the screw is on the subframe and pull on the screw like crazy... I'm SCARED!

I followed your instructions exactly regarding the vibration damper: I adjusted it first with the old one and then checked it again with the new one (it's quite easy to do that with a ruler made of spring steel). And that's precisely why I'm going to keep the old vibration damper.

Thank you also for the link to the pump. Presumably, the hills are what you measure with the gauge? And theoretically, it should then be possible to adjust the pump precisely to a "wrong" hill using the gauge... assuming that there are even such things as right and wrong hills. Isn't the marking on the wheel the only difference?

Best regards,
Michael.

wolle wrote:

There is a "bump" on each cylinder. Since the entire arrangement is symmetrical, ... I would also argue that it works if you've turned it too far and the... Then, the following "hill" is used.

No, that won't work because the association with the correct cylinder would no longer be possible.
This is because it is achieved through the rotation of the feeding piston!

There used to be some great intake manifolds on the 1.6L four-cylinder engines that had an identical hole.
When the timing was offset by 180 degrees for injection, nothing worked because the injection occurred at the end of the exhaust stroke.

Best regards, Michael.

Hi there,
I see you're referring to the RLF.
In my humble opinion:
- The support bracket 3256 seems to rest against the engine block not with the screw itself, but with the flattened area on its neck; this also explains why the tightening torque works.
- Regarding the central bolt, no lubrication is mentioned (i.e., the ET bolt will be installed as supplied by VAG);
- For the timing belt replacement/removal of the vibration damper, it should be sufficient to remove the four M8 screws. The front sprocket only needs to be removed for replacing the oil seal.
I'm going to remove the link from your post due to copyright concerns.
hg
Herbert.

mdonau wrote:

wolle wrote: There is a "bump" on each cylinder. Since the entire arrangement is symmetrical, ... I would also argue that it works if you've turned it too far and the... then the following "hill" is used. No, that won't work because the association with the correct cylinder would no longer be possible. The reason is that this happens due to the rotation of the feeding piston.

Here's the translation:

"The fact is: The fuel pump was slightly out of alignment before I changed the timing belt, and the engine ran perfectly fine. The only issue was an occasional error code indicating a problem with the injector control valve. However, I don't believe this was caused by the misaligned fuel pump, but rather by a loose connection. Therefore, I suspect that this error will reappear at some point."

@Herbert: First of all, I'm sorry about the link.

The engine stand does not rest against the motor block with its flattened part. Perhaps this applies to other engines, but in the case of the AEL, there is nothing for it to rest on. Or have I completely misunderstood something? Please clarify .

I also replaced the oil seal. However, regardless of that, the four M8 screws are not sufficient to remove the vibration damper because the central screw presses the vibration damper against the diamond disc and onto the crankshaft. The four M8 screws only hold the spur gear on the vibration damper, which is driven by the damper itself and not by the groove in the crankshaft.

The engine is running again now. I could have saved myself the trouble of setting the timing with the measuring gauge, because afterwards I still had to loosen the screw on the rear camshaft wheel about 100 times until VAG-COM finally accepted the reading. I really should have made the initial adjustment as described by Wolle.

Today, I had significant problems with the tensioner pulley for the front timing belt, which hopefully are now resolved (I still need to test and observe). I will report on that tomorrow.

Best regards,
Michael.

Hi there,
Am I mistaken in thinking that there is no direct connection between the timing chain and the crankshaft, as there is in a 4-cylinder engine?
The pipe for the oil separator screw on the counter-holder is flattened, which must have a reason, so something might be obstructing it. It should provide support when turning clockwise. If not, perhaps insert a suitable piece between this pipe and the block?
hg
Herbert.

Hi everyone,

@Michael

Sorry for not replying yesterday.
I had typed a really long answer throughout the day. When I finally wanted to send it, my session had, of course, expired. After entering my name and password (unfortunately, I mistyped it once), everything was gone .
I simply didn't have enough time to type everything out again...

Here is a short version:
The impeller is installed within the ESP (Electric Stability Program) such that the wave pattern faces towards the ESP wheel. The roller ring located behind it provides the deflection of the impeller.
It's likely that the clock will pick up the "signal" from the back of the rotor. I'm not familiar with setting up the clock this way, and I don't really know what it looks like.

You can also slightly loosen the pump on its bracket (using one Allen key and three 13mm bolts) and then adjust it dynamically using VCDS. This is a very quick process and provides highly accurate results.
The pump is mounted on the bracket in a way that allows it to rotate. Therefore, you can now adjust the feedback (FB) "online" by rotating the pump. This only involves very small movements, not large millimeter adjustments .

If you loosen the third 13mm screw (the outermost one) only after the engine is already running and while simultaneously holding the pump with your other hand, it won't suddenly adjust too much. There isn't that much back pressure. Now you can essentially see live in VCDS how the fuel quantity changes as you turn the pump.
This engine seems to like having the fuel-air mixture adjusted slightly towards a richer setting.


Regarding your error concerning the NHG (National Health Grant), it doesn't necessarily have to be the NHG itself that has a defect. As far as I recall, it could also be caused by the settings of the MSW (Medical Service Workflow).
However, I haven't yet been able to figure out how to counteract that.
I'm actually experiencing the same problem with that error code. However, since the Audi is running fine otherwise, I haven't really prioritized fixing it. I simply don't have enough time for it right now.


@Herbert

The flattening on the counter-holder is also baffling to me. In fact, it's true that he can't support himself anywhere during the AEL/AAT process. I also don't know where a special fixture could be installed on this engine that would explain the flattening...
Perhaps the counter-holder will also be used for other models, where the reason for its flattened shape becomes clear...
But placing it on the support frame is easy, risk-free, and... even that too... It works great.

Regarding the vibration damper:
It is indeed the case that the central screw needs to be removed.
The pinion gear itself is connected to the vibration damper using four screws. The mechanical connection to the rear axle housing (KW) is only provided by the central screw.
However, there is a direct connection between the front wheel and the rear wheel.
"The fact that the central screw also secures the SD (presumably a sensor or device) is, in my opinion, because the load on the SD is so high that the four screws alone would not be secure enough."

@mdonau
I need to investigate your explanation regarding the rotating feeder piston in order to better understand it.
I'll take a look at that broken pump I acquired some time ago for testing purposes.
Michael says it's working... Based on my gut feeling, I would also say that this pump (VP37) is likely functioning correctly.
But I'll remain cautious for now .


In that spirit... Have a great day, everyone.

Best regards,
Wool.

Hello everyone,

First of all, thank you very much to all of you for your numerous responses!

@wolle: I am very sorry about the expired session! Unfortunately, I have had to experience this many times before . That's why I now make it a habit to always copy long responses to the clipboard first, before clicking on any buttons.

"If the rotor is pointing backwards, the clock will actually receive the signal from the back of the rotor, because the clock is plugged in from the front instead of being inserted through the central screw between the fuel injectors. Based on my experience today, I wouldn't recommend using the clock for this adjustment. Without the clock, it's possible to achieve a similar level of accuracy so that the engine at least starts. Even with the clock, it's difficult to get it precise enough that you don't still need to correct it with VAG-COM. With the 1T model, you have to use the clock because there's no other way to adjust it via VAG-COM. Using the clock also has the disadvantage of introducing air into the ESP system. According to RLF (presumably a reference document), you should bleed the system afterwards, although I don't know how to do that. I simply let it run for two minutes on the first start, and that was enough to bleed it so that it would start. And after about 100 km, all the air was probably gone, so it started reliably."

I also read in the repair manual that you're supposed to turn the pump. However, I couldn't reach the lower screw with my tools. You probably need a very slim wrench for that. So, I did it on the camshaft wheel instead. I realized that we're only talking about fractions of a millimeter here. And because I had to turn off the engine each time to be able to do it, and there was always a risk of accidentally damaging something when loosening the screw, it took me many attempts. Ultimately, I managed it by turning the engine to the top dead center (TDC) position at the front left wheel in 6th gear after each attempt, and marking the camshaft wheel. Without those markings, I wouldn't have had a chance. But there's probably a more elegant way to do it on the pump.

What does "early" mean in VAG-COM? Does it refer to larger or smaller numbers? In my case, the numbers are now slightly smaller than the middle line on the graph in the RLF, but still within the tolerance range. They're roughly in the middle between the middle line and the lower edge. And why would the engine behave like that?

What is an MSW?

The flattening on the counter-holder is not only unclear but also counterproductive because it's precisely in that direction that it experiences stress when the screw is tightened. If it were rounded, there would be at least a little more support surface available.

And now, let's talk about the problems with the tensioner roller:

After the initial start, I carefully applied some throttle. Despite working meticulously, I always feel a certain respect and apprehension when it comes to timing belt replacement, and I'm afraid of accidentally connecting valves with sealant . And at approximately 1050 RPM, I actually heard a metallic clattering sound. At that point, I didn't apply any more throttle, but instead asked another person to listen to where the noise was coming from. When I inadvertently gave it a little more gas while doing that, I noticed that the noise disappeared again above 1100 RPM.

Irgendwann hat sich dann rausgestellt, daß das Klappern von der Spannrolle kam. Dabei hab ich dann festgestellt, daß sie etwas überspannt war, obwohl ich sie genau wie im RLF beschrieben auf den Rechten Rand des Pfeils gestellt hatte und die Schraube mit 22 Nm angezogen und danach den Motor zwei Umdrehungen durchgedreht und die Spannung kontrolliert hatte. Also hab ich sie zunächst mit nem Gabelschlüssel wieder entspannt und richtig gespannt und wieder so weit fest gedreht, bis der Gabelschlüssel kurz davor war, das Maul aufzusperren. Danach war das Klappern leiser, aber nach einer Probefahrt war die Spannrolle sehr weit entspannt, vermutlich weil die Schraube nicht fest genug angezogen war. Also nochmal entspannt und richtig gespannt (auf den rechten Rand des Pfeils) und diesmal mit nem Ringschlüssel, den ich mir extra dafür so dünn schleifen mußte, daß er am Schwingungsdämpfer verobei kommt, so fest gezogen, wie ich nur konnte. Jetzt ist sie nach ner Probefahrt wieder überspannt (ca. 3mm rechts vom rechten Rand des Pfeils), aber sie hat sich zumindest nicht mehr entspannt und das Klappern ist auch weg. Das werde ich jetzt mal die nächsten 1000 km genau beobachten, ob sie die Spannung hält. Wenn ja, bin ich zufrieden. AOtherwise, I guess I'll have to remove the vibration damper again so I can access it with the torque wrench.

But two questions remain unanswered:

Where did that rattling sound come from?

2. Are 22 Nm really enough?

Best regards,
Michael.

Hi Michael,

Exactly... The clipboard has now become my friend as well.

I'm a bit surprised that you can't reach all the screws on the ESP.
I meant the screws that are used to attach the ESP to the console.
The M13 screws are actually quite easy to reach. The only thing is that the Allen key socket is a bit hidden (between the pump and the cylinder head). You need to use a long Allen key to access it. I put a small open-end wrench over the Allen key and was able to turn it easily with that.
It's important, and I completely forgot to mention this, that after rotating the ESP, you should disconnect all of the injector lines from the pump once. This releases any tension that may have built up in the lines due to the rotation, preventing them from breaking later.

When building a counter-holder for the front wheel, you can also easily adjust the brake caliper on the rear front wheel. Simply loosen the bolt slightly so that the rotation of the front wheel can be achieved using the counter-holder.
You don't need to adjust the timing on the engine for that. It's completely independent of that.

Unfortunately, I can't tell you which value is correct. You should definitely be able to find that out through a search. However, I always set something slightly above the midpoint using VCDS. I can't explain why this engine prefers it. I just copied that setting from somewhere else.


MSW: This is the quantity switchgear, located at the top of the ESP (Electrostatic Precipitator).

Normally, the electronic solenoid pump (ESP) is vented using a vacuum pump. Fortunately, the VP37 isn't quite as sensitive when it comes to organ playing. The VP44 from the V6 engine tends to fail in this situation...

"Your tensioner problem sounds really bad. I didn't have any issues with mine, but I also tightened the screw quite firmly. Definitely more than 22 Nm. I don't trust that value either..."
Where that rattling sound might have come from... hmmm... I still don't have a clue.
With a belt that's "too loose," the strap might be slipping somewhere.

I'm keeping my fingers crossed that everything stays well...

Best regards,
Wool.

Hi Wolle,

Now, finally, after tightening the bolt again with the wrench until my hand hurt, it seems my tensioner pulley is stable. At least, it hasn't loosened up in the last 100 kilometers.

If I really wanted to, I'm sure I could have also accessed the Allen screw on the ESP. But the camshaft screw seemed easier, partly because you don't have to disconnect any lines behind it. I do have a holding tool for the camshaft. I only turned the engine to Top Dead Center (TDC) to be able to work with the same markings each time.

It seems that an earlier start time corresponds to larger numbers in the VAG-COM system. Throughout the adjustment process, I also had the impression that it ran very well with large numbers far outside the tolerance range, while with smaller numbers within the tolerance range, it sounded like it would never warm up. Now I've set it to the upper half of the tolerance range.

I don't think the belt was slipping; the sound clearly indicated metal on metal.

Now I hope that everything stays okay. Of course, I will still monitor the vehicle for the next 1000 kilometers, and after that, I will also check the tensioner pulley during the oil change.

Best regards,
Michael.