Systematic approach for identifying defects. WaPu 1.9 TDI 110HP AHF?

Hello comrades

Sure, here's the translation:

"First, a little bit of introductory stuff:"

I still have a Golf IV Estate (station wagon) from the year 2000 in my fleet.
with AHF (acute heart failure) and 350,000 km (mileage). He runs like a dream, despite the mileage.
1. "Serienstand" refers to the current score. I've had the vehicle for almost 5 months.
And I can say, so far: technically excellent, no defects. Long-distance vehicles.
The engine, purchased from an older gentleman, appeared to have 50,000 km on it, but it was visibly dirty.
The test drive before the purchase went perfectly, according to the textbook.

He got a complete overhaul from me right after I bought it.

- VTG cleaned.
- Intake manifold cleaned (removed and cleaned).
- Intercooler cleaned (it appears this was never cleaned before, judging by the dirt and the date).
It had just under 15ml of oil in it... not worth mentioning, so)
- and all the standard items: all the filters, Castrol 10W-40 oil, etc.
- Compression: 2 bar, "new" condition.
- Nozzles all in good condition - BOSCH service.
- The ZR (likely referring to a component like a Zener diode or a similar resistor) has not yet been replaced, even after visual inspection.
The 90,000 km service interval hasn't come up yet...
- The ESP isn't interfering at all - it's working flawlessly!
- 1 short flash, 1.5 rotations, on...

Yesterday evening, my wife came home and asked if I had heard that "strange" noise... I drove 150km during the day, and everything seemed fine to my ears. So, I got into the car, started it up, and lo and behold:
"Jieh Jieh Jieh Jieh Jieh Jieh Jieh Jieh Jieh Jieh Jieh Jieh...." (Outdoor temperature: 15°C)

Clearly audible, in my opinion, it's either a belt or a bearing.
The noise decreased after 150 meters of driving and then disappeared.
But it made me think of the Air Force. Coolant temperature: OK.

Rapid test result:
- Place a white cloth under the block overnight (no undercarriage protection...).
- This morning, I disconnected the return line to the expansion tank.
and hung in a verschandeln glass jar, allowing a significant current to flow.
- The belt shows no signs of wear and is clean.

Here's another idea on how I could check the water pump without having to disassemble everything unnecessarily, since so far, nothing seems obviously wrong. Do water pumps tend to fail completely and suddenly, or do they usually start with leaks and gradually become worse?

Thank you very much and best regards!

Caution: Check the tensioner roller!

A free-running pulley would also be a possible option.

The rollers seem to be in good condition. I can make the top roller rotate freely by pressing down on the belt, and it doesn't have any scratches or play. I can only monitor the others visually, and just now, without the ZR cover, they didn't appear to be doing anything unusual while idling.

Due to the mileage, I'm ruling out any issues with the timing chain; the timing chain is practically new (8000 km).

Thank you for your tips! More ideas?

Deus Violentia wrote:

.. LiMa is almost new (8000 km)

.
And is the free-running feature also new?

Deus Violentia wrote:

Thank you for your tips! More ideas?

A V-belt can quickly become slack and detach from the drive pulley. Then you can narrow down which belt is making the noise.

In the case of a ZR (short circuit), quick action is crucial. With a KRR (residual current circuit breaker), it's not quite as urgent (although it can still cause significant damage in the event of a rupture).

@ Wiesel: The "Freilauf" is also a new role.
@ Guste: I'll be changing the ZR soon anyway, but as I said: the rollers are spinning freely.

Hello,

Quote:

"Jieh Jieh Jieh Jieh Jieh Jieh Jieh Jieh Jieh Jieh Jieh Jieh...."

Does that repeat approximately with the timing belt's service interval?
A belt-driven roller might make noise as it passes a specific point in the timing mechanism, for example, when it passes over the labeled area (or a damaged area).
If necessary, spray the belt or the suspected roller with silicone spray.
Otherwise, spray any suspicious waves with a little Caramba.
Okay, I understand. Please provide the German text you would like me to translate into English. I will only provide the translation.
Herbert.

@Herbert: The periodicity (what a great word ) could not be checked because the noise disappeared after those 150 meters of driving in the evening, and I only removed the belt cover yesterday.

I'm always careful with lubricants when it comes to the timing belt, because you never really know exactly what the rubber coating/layering of the belt says about its compatibility with certain lubricants. I'll definitely try cranking the engine again and watch the belt in slow motion, but I didn't see anything unusual when it was idling.

My A3 has been doing the same thing for about 3 years now.
The timing belt and pulleys are 50,000 km old.
The frequency is precisely in sync with the timing belt's rotation, which is approximately every 6 engine revolutions.
A faulty ball bearing would likely result in a higher speed, as the rollers have a smaller circumference than the crankshaft pulley, and would therefore rotate faster.
It seems like the timing belt is slightly misaligned, almost oval-shaped. I'm not sure how else to describe it.
So, it brushes against the impeller or another wheel with each rotation and then makes a "fieep" sound.
However, I could also not detect any fraying or wear.