Belt Noise on Audi ALH Engine

Hello everyone!

Inspired by Rainer's unfortunate experience with the faulty tensioner pulley, I would like to discuss a noise that has been present since I purchased the G4 ALH (August 2004 with 147,000 km, now November 2004 with 156,000 km).

The noise definitely comes from a belt drive system, so it could be the ribbed V-belt (my guess), or possibly even the timing belt.
The "grinding noise" is particularly noticeable immediately after a cold start, but then it almost completely disappears after driving for a certain distance.
It's a periodic "tick-tick-tick" sound, whose frequency is directly linked to the engine speed. By the way, the vehicle doesn't have air conditioning.
At idle speed, I would estimate the repetition frequency to be approximately 1-2 Hz, which could only be interpreted as a beat frequency. At an idle speed of approximately 9001 RPM, an effect would become apparent at the crankshaft pulley with about 15 Hz and at the pump/blower wheel with about 7.5 Hz.

So, I'm wondering where this noise might be coming from. I still suspect it's the serpentine belt, as I believe (though I'm not entirely sure) that I can change the intensity of the noise slightly by varying the load on the alternator.

However, how does this relate to the engine temperature?

It might be the water pump, or even the tensioner pulley for the serpentine belt. If anyone recognizes this noise and possibly knows the cause or consequences of not fixing it, please don't hesitate to share your information with me.

The news about Rainer's faulty tensioner is actually making me a bit worried.
Okay, the car needs to drive about 1000 km per week, mostly on highways. So, the engine's RPM is relatively high. If anything breaks down, it will be a significant issue.

Thank you for your support.

Regards,
Alex.

Hi Alex,

Just try turning on all the electrical components, like headlights and high beams, with a cold engine. If the serpentine belt is faulty, you should hear a change in the noise.

donalexo wrote:

It's a periodic "tick-tick-tick" sound, whose frequency is fixedly linked to the engine speed. By the way, the vehicle doesn't have air conditioning. At idle speed, I would estimate the repetition frequency to be approximately 1-2 Hz, which could only be interpreted as a beat frequency. At an idle speed of approximately 9001 RPM, an effect would become apparent at the crankshaft pulley with about 15 Hz and at the pump/blower wheel with about 7.5 Hz. So, I'm wondering where this noise might be coming from.

What about a "slipping" spot on the timing chain or alternator belt? It would pass by the tensioners at a slower rate than the engine is rotating .

I would (as a precaution) mark the timing chain with a paint marker, then rotate the engine by pushing it in the highest gear until the mark reappears (ugh), and while doing so, check the condition of both belts along their entire length.

After replacing the serpentine belt, I noticed a significantly reduced amount of noise.

It probably comes from the back side of the belt.

The old belt was smooth and therefore likely adhered well to the tensioner pulley, which caused noise.

The new one was quite rough, which meant the tensioner didn't really "stick" to it properly.

Just swap the crankshaft position sensor (KRR) – or isn't it a 10-minute job like it is on the 1Z engine?

Okay, please provide the German text you would like me to translate into English. I will only provide the translation.

Hello everyone,

After changing the engine oil and transmission oil on my ALH Golf today, I investigated the belt noise issue further.

To my dismay, the noise isn't coming from the serpentine belt as I initially suspected, but definitely from the timing belt. The noise occurs exactly once per rotation of the timing belt, which I was able to determine by marking the belt.
After checking the outer edge of the timing belt, I noticed a spot that is several centimeters long and shows clear signs of wear. At this point, the inner steel fiber reinforcement becomes visible .
I couldn't measure the strap width exactly while it was installed, but it's approximately 24mm.
I then got under the vehicle while the engine was running and the car was raised on jacks, and examined the pulley's alignment. It didn't look very good at all!
Surely the ALH should be above the issue of torque wrench screws, right?

I'm somehow feeling uneasy now, because the noise definitely seems to be caused by the timing belt. The wear on the width should actually still be within acceptable limits, but who knows how long the belt will last under these circumstances .

What would you do? The car needs to cover approximately 1000 km per week, so reliability is essential.

I'm not entirely clear why the belt should always slip specifically at that bare spot. Surely, there must be an unfavorable combination of factors, such as misalignment between the NW pulley, pump pulley, crankshaft pulley, water pump pulley, and tensioner pulley, or how do you see it?

Should I replace the timing belt next weekend for safety reasons, or should I just leave the car where it is? How would you approach this situation?


Thank you for your help.

Regards,
Alex.

donalexo wrote:

Should I replace the timing chain next weekend for safety reasons, or should I just leave the vehicle parked? How would you proceed?

Replace the ZR (and possibly other components like belts, pulleys, etc., depending on mileage) as soon as possible.
Until then, try to drive as little as possible and avoid high RPMs (because the pump requires a lot of power at those speeds due to the high injection pressure).

Hi Ulf!

The current mileage is 156,000 km, which means the next scheduled timing belt replacement would be at 180,000 km. However, I don't feel comfortable with the idea of driving another 24,000 km with the timing belt given these accompanying issues.

I find it extremely strange that the noise almost completely disappears when the engine is warm. I drove around again tonight. At first, the noise was very prominent. However, after a few kilometers, it almost completely disappeared.
Right now, I still don't understand how that could be possible.

Beim Ölwechsel ist mir noch aufgefallen, dass vermutlich der KW-Simmering ganz leicht leckt. Im ersten Moment scheint die Ölwanne an der hinteren Ecke undicht zu sein. Wenn man dann genauer hinsieht, erkennt man, dass das Öl vom Fahrtwind und der Schwerkraft in diese Richtung gedrückt wird, der Ursprung sich jedoch hinter der unetren ZR-Abdeckung an der KW befindet. AlThis is a ZR seal.

If I'm replacing the timing belt, I will definitely replace all tensioners and idler pulleys, as well as the water pump. The timing belt crankshaft seal should also be replaced at the same time. This procedure would require removing the timing belt sprocket anyway, which should also resolve any issues related to the crankshaft bolts.

The only thing that needs to be clarified is to what extent the used car warranty would apply in this case. Frankly, I'm so fed up with authorized workshops that just thinking about it makes me feel sick.
Erst kürzlich habe ich das Pumpentiming sorgfältigsts auf die "früh"-Linie justiert, damit dann die "Flachwerkstatt" NW- und Pumpentiming außer Tritt bringt. NEIN!!!

I'm still a bit unsure about the cause and, consequently, what action needs to be taken. Let's see if I can get some new insights tomorrow. I'll check with VAG-COM again to see if the pump timing has changed since the last adjustment. If it has, then the crankshaft pulley bolt may also have been affected.

Okay, I've produced a lot of text now, but I still haven't made a decision about the solution.
Please share your opinions and suggestions on this topic so that I can gain a clearer understanding.

Sure, here's the translation:

"Thank you in advance."

Regards,
Alex.

A friend with a Golf4 ALH (produced in 2000) had the exact same problem. The cause was a timing belt that was too tightly tensioned, and apparently it was not a very good quality timing belt.

'I replaced it and it's been quiet ever since. It's possible that the initial damage also came from an improper replacement at 90,000 km. The belt was too tight, they adjusted it but left the belt as is. Maybe it's holding a grudge against you now?'

The 'siffende Simmering' is an ALH (Antifreeze Leak Head) issue, which my two cars also developed over time. However, according to VW, it's acceptable as long as it remains within the range of 'sweating.' That's what happened with mine too...

donalexo wrote:

Hi Ulf! However, I don't feel good about the idea of driving the ZR another 24,000 km with these accompanying issues.

I also meant the fastest possible "unscheduled" change.

Hello everyone!

First of all, thank you for your responses.

Now that you're taking this as seriously as I am, I will definitely have the timing belt replaced (or changed) as soon as possible.

I have thoroughly read the used car warranty terms today and I've come to the conclusion that the dealer is responsible for repairing the timing belt. Furthermore, they are also responsible for replacing the leaking crankshaft oil seal .

Actually, I'm generally reluctant to leave the car with the dealer for such a delicate job, but on the other hand, I don't see why I should incur the costs and time involved if the used car warranty covers it.

Now, I suppose I'll have to grit my teeth and bring the good piece to the dealer's lot, hoping that he does his job properly. (That takes a lot of hope and optimism.)

I just sent the dealer a detailed email explaining my issue. I also made sure to include references to the most important sections of the used car warranty terms and conditions.
I'm curious to see the reaction tomorrow. If he objects, there will be real pressure (that's what my comprehensive insurance ) is for.

I will keep you updated.

Regards,
Alex.

Hello everyone,


I just picked up the Golf from the dealer. The following parts were replaced:

- Timing belt
- 4 guide rollers / tension rollers
- Water pump
- KW-Simmering
- V-ribbed belt
- Small parts (fasteners, washers, etc.)

The belt noise is definitely gone . I immediately went to the workshop yard and put my ear under the open hood, listening to both belt drives while the machine was running. I could no longer detect any grinding noises.

Subjectively, the engine power and torque delivery feel good, which means the ignition timing and fuel injection timing seem to be well-tuned (which is quite remarkable). I'll probably need to use a laptop and VAG-COM this weekend to get more precise information about the fuel injection timing.

I am now relieved in two respects. Firstly, because the Damocles' sword of a potential warranty claim is no longer hanging over me/my wife. Secondly, it's a relief for my wallet, as the used car warranty covered the full labor costs but almost no material costs. The warranty coverage regarding materials only covers 60% of the timing belt (due to mileage tiers). The tensioners and idler pulleys, and the water pump would normally have remained untouched if I hadn't given the additional order. Now, however, a considerable amount of €303.88 has been incurred for materials, which surprised me quite a bit.
What does a timing belt replacement, including labor costs, actually cost then?

I will re-check the prices of the parts to rule out any suspicion that the workshop is unfairly profiting from the chargeable parts when providing warranty services.

I had the old parts put in my car and took some pictures of them right before they were replaced.
You can clearly see the area of flank wear on the tire's sidewall, where the steel reinforcement is exposed.
There's a scratch on the roller that covers only a small portion of its circumference. I wonder if something might have gotten stuck in there at some point?

All the bearings of the guide/tension rollers feel good.

Enjoy watching!

Regards,
Alex.


(Edit Ulf:)
I've taken the liberty of resizing the pictures so that they can be viewed without having to download them.

donalexo wrote:

You can clearly see the area with flank wear on the ZR, where the steel reinforcement becomes visible.

Hmm, I don't see anything obviously bad there... Which specific area are you referring to in which image?

Hi Ulf!

The close-up images of the timing belt show the "bare" area. Further along, the flank is black again, meaning it's rubberized. Only in the photographed area is the steel fabric visible.

Regards,
Alex.

donalexo wrote:

Hi Ulf! The close-up images of the timing belt show the "bare" area. Further along, the flank is black again, meaning it's rubberized. Only in the photographed area is the steel fabric visible. Regards, Alex

Hello,

I actually thought those were tissue fibers (synthetic fiber). In my experience, all timing belts have looked like yours so far.
As long as the width of the timing belt is almost within specification and no further damage is visible, I don't see any need to replace the belts at this time.

Best regards, Rainer.

Hello Rainer!

Looking at it objectively, I agree with you.
However, you should have experienced the sound of the belt running in the engine at idle speed firsthand .

I think you would have voluntarily started the exchange process. That really sounded criminal. Even with a very cold engine (meaning a heavily clattering TDI), the belt noise was prominent both inside and outside the vehicle .

In my opinion, the parts still look remarkably good.
But it's better this way than risking an engine failure .

Regards,
Alex.

Hi everyone!

That's really not steel mesh. I could cut my old one with a knife.