Timing Belt Tension: 1.9 TDI AHF Help

1.9 TDI AHF/ASV/ALH VP37:

Yesterday, I replaced the timing belt, and it was quite late (1:00 AM ). I have a question about the tensioner pulley. I think I may have tightened it too much. In the example picture, you can see a small ledge behind the raised section on the lower segment (which should be aligned with the slot). This ledge ends at an angle.

"The small section behind the raised area with the slot is now misaligned, so it's a bit too tight. The right edge of the raised area is touching the left edge of the slot. Is this a serious problem? Subjectively, the engine seems to run better than before, and the belt isn't making any unusual noises. After three attempts, each with two rotations, all positions (the flywheel mark in the inspection window, the ESP sensor, and the camshaft) are now perfectly aligned."

I've illustrated my problem manually; the nose on the lower segment is meant to represent the raised area that should align with the recess at the top.

Left: My situation - Right: This is supposedly how it should be.

Deviation from the target value: approximately 1.5 mm - 2 mm.

Do I need to completely release the roller if I should only reduce the tension a little? Or is it theoretically also enough to just turn it back further and then pre-tension it again to the correct value? I would appreciate some advice, because I don't want to have to disassemble everything again.

In this video, you can see what I mean, but the voltage is too low here.

http://www.youtube.com/watch?v=oD173rY5aIA

I don't have a car jack and can't take a picture, but I would if I could!

Deus Violentia wrote:

1.9 TDI AHF/ASV/ALH VP37: Bei mir fluchtet jetzt der kleine Absatz hinter der Erhöhung mit dem Schlitz, also etwas zu weit gespannt. Die rechte Kante der Erhöhung steht also an der linken Kante des Schlitzes. IIs that tragic? Do I need to completely release the roller if I should only reduce the tension a little? Or is it theoretically also enough to just turn it back further and then pre-tension it again to the correct value? I would appreciate some advice, because I don't want to have to take the whole thing apart again.

Hi, as you described it, you can leave it like that. The modulation range allows for it. In any case, the ZR will loosen up over time.
You might need to readjust it; you'll have to turn the knob further back until it clicks back into place on its own. You'll feel it when it's right. Then you can tighten it again.
Best regards, Ronny.

Hello,

It also depends somewhat on the engine temperature; when the engine is hot, the engine block expands "higher," which increases the tension of the timing belt.
So, if it's already quite tight, you should loosen it up a bit more.

Best regards, Rainer.

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If you still want to readjust it, the knob needs to be turned further back until it clicks back into place on its own.

This is crucial . Tell me, can I turn the roller back far enough if I only remove the upper ZR cover? I can access the tensioner, but how far do I need to turn it back so that it snaps back into place? Any vague ideas?

Don't worry about the tension. I even know people who do it intentionally to prevent the engine from losing tension too quickly. Supposedly, after 100,000 km, the engine runs even better, but I don't know if that's true.

Okay, so you want to know how to loosen and re-tension the tensioner without actually getting to it? You'll have to explain that to me because simply removing the cover won't do it.

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

"Hello."

"I thought I could reach the tensioning element with a wrench if I remove the upper timing cover. At least, that's what I imagined!"

I once borrowed a picture of the "Diesel Bear."

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Even though the tension wrench is quite low, I thought(!), maybe it would work?

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The tensioner absorbs movements of the belt drive and maintains constant tension. However, I'm wondering how far the rear stop is from the ideal position (the groove height). I think that in many cases, the tensioner roller breaks because the damper can't move freely; instead, it always hits the end stop because the belt is tightened too much.

I think I'll check back in two days; that's when I'll be home again.

Let's leave it as is for now and re-evaluate after 500 km.
Based on experience, it will probably change again slightly.

Quote:

It also depends somewhat on the engine temperature; when the engine is hot, the engine block expands "higher," and the timing belt tension increases. So, if it's already quite tight, you should loosen it up a bit more.

Yes, of course, the engine and timing belt pulleys expand.

Quote:

Hey, can I turn the roller back far enough if I only remove the upper ZR cover?

It should be fine.

Quote:

How far do I need to turn it back so that it snaps back into place?

Around 60-90 degrees, you'll notice it. You might want to use a small mirror to help when tightening it.

Okay, so I just connect to the OT, ESP, and NW ports and start? Or do I not even need to connect anything?

Deus Violentia wrote:

So, should I connect to OT, ESP, and NW and then start? Or do I not even need to connect anything?

Why do you want to do that?

Adjust the tensioner correctly and you're done...

Since I've personally experienced an anterior hip fusion (AHF) before, I'm quite certain that this can be done in 10 minutes because all it requires is unclipping the upper timing belt cover.

Best regards, Rainer.

I thought the same thing as you wrote, but I wasn't entirely sure if there was a possibility that something might get misaligned or out of sync.

But the belt is correctly installed, and the wheels, i.e., the screws, are all tight as they should be. Okay, I will report back on what I find out – and that's with my own photo!

Hi there,
According to the RLF (presumably a reference manual), the tensioning mechanism should be rotated clockwise. This means you would theoretically hold the tensioning key with the handle facing upwards. However, in the pictures, it looks like it was rotated counter-clockwise, which is evident from the position of the eccentric.
The belt is properly tensioned when the notch and the ridge are facing each other. I adjust it to at least 20 degrees, but no more than slightly warm to the touch, as they are also installed at room temperature in the factory.
If it needs to be adjusted again, rotate the roller back as far as possible until the belt is clearly no longer under tension.
A higher tension puts more stress on the timing belt and is not in accordance with the design specifications.
After tightening the strings, check the neck relief and nut slot depth.
I check the belt tension every 15,000 km (approximately 9,300 miles) during the oil change, while the manufacturer recommends checking it every 30,000 km (approximately 18,600 miles).
hg
Herbert.

The belt tension was checked again and readjusted to the correct value. This was achieved by removing the upper timing cover and the intercooler pipe between the EGR valve and the intercooler.