Hydraulic lifters or injectors?

Hello,

For a few months now, my AFN has been making a louder knocking sound...
(Mileage: 181,000 km)


This harsh knocking is particularly noticeable during the warm-up phase, but 1-2 minutes after a cold start, everything sounds normal again.

My question:

What is the more likely cause? Could it be a faulty hydraulic lifter (I performed a hydraulic lifter test according to ****Win, but I couldn't detect any play) or is an injector starting to fail? The engine's power delivery is perfect, and there's no excessive soot or anything like that. The fuel consumption is also normal.

All these facts seem to me, personally, to point more towards a faulty hydraulic lifter.

What do you think about this? Has anyone had similar experiences and been able to fix the problem?

How do you approach a problem like this? Do you replace all the valve lifters and hope that fixes it? I can't detect any noticeable play in any of the valve lifters...


Thank you in advance for your help.

Best regards,
Achim

AchimTZR wrote:

How does one proceed with such a problem?

Hello Achim,

Try testing the injectors by, with the engine running (cold), disconnecting and reconnecting the fuel lines one by one. If the knocking disappears, it's likely due to the injector in question. This test worked on the older diesel engines, but I'm not entirely sure what the TDI will say about it, especially if you disconnect the line at the common rail -> waiting for the injector experts.

It's not easy to determine the play in the crankshaft. You have to press down firmly with a piece of wood and then carefully observe whether the crankshaft sinks in at all. In our Audi, after 270,000 km, only the slightest play was detectable. However, replacing them resulted in smoother running. If you're going to replace the timing belt soon anyway, the investment is hardly worth it (the cost is, I believe, around 50 euros for the set). Otherwise, I would ignore it and avoid stressing the cold engine .

Hello.

@Achim
Definitely replace all the hydraulic fluids if they need to be changed.

@ VW engine experts.
Did GTIs used to have reinforced hydraulic lifters? Could those possibly fit and last a bit longer?

Best regards!

Hi,

I'm currently in the process of replacing all the hydraulic components, and I'll know tonight whether it makes a difference or not.
The price for all Hydros was 145.37 EUR.

EXPENSIVE FUN

Greetings.
Okay, here's the translation:

Achim.

What actually happens when you drive with defective or 'worn-out' hydraulic lifters?

Best regards, Peter.

It depends on the type of wear.

- nothing
- Loss of performance due to valves not opening fully.
- Air leakage due to valves not sealing properly (which often results in damage to the head).
- Significant wear on rocker arms/lifters or camshaft.

- Valves can burn out.

- engine damage caused by melting parts.

- Head damage, including camshaft, if the hydraulic lifters fail.

@AchimTZR:

Have you replaced the hydrofoils yet? Please let us know your feedback as soon as you have results!

Thank you .

Regards,
Alex.

Hi,

Okay, the hydraulic lifters are installed.

Conclusion:

The engine runs noticeably smoother and more quietly than before. However, to be honest, I expected more. I now suspect that one of the fuel injectors may not be seated correctly in its housing.

To my knowledge, the engine mounts for the ESD are quite rigid, but they still allow for a certain amount of "flex," which can significantly alter the sound of the engine.
I'm attributing the tacking issue to the first cylinder, as that's the one most likely to slip when using the screwdriver-ear method!

But I can recommend that everyone try it out sometime, if they happen to have 167 EUR too much in their wallet .
Even considering the mileage of my engine, which is 185,000 km, this is certainly something that should be done so that it can continue to provide powerful acceleration in the mornings for a long time.

Furthermore, there are reportedly 8 hydraulic lifters available for the AFN engine in E***, supposedly from the company INA, at a price of only 45 EUR.
It certainly sounds tempting, but my brother once ordered a similar set from there. The result was disappointing: The design differs from the originals, and you can't find any company logos or similar markings on the pushrods, unlike the VW set or the ones that were originally installed.

So, it is to be assumed that this is once again "absolute original equipment quality," as is often advertised in E***!

Greetings.
Okay, here's the translation:

Achim.

Hello Achim!

Thank you for your feedback!

How long did it take you to replace the hydraulic lifters? Did you combine the repair with the timing belt replacement (since the timing belt has to be removed anyway, and the camshaft needs to come out)?

Have you noticed any excessive wear marks on the valve lifters or the camshaft?

Do you still have the original injectors installed at 185,000 km? However, I find the theory about the misaligned injector position doubtful, because those parts are usually only removed when they are taken out.

Has the aggressive engine knocking during the warm-up phase been reduced, or did the Hydros system not make any difference?

Regards,
Alex.

I'm not very familiar with AFN engines, but I had a similar problem with a AJM engine (85 kW PD): a ticking noise when the engine was warming up, which later became noticeable even when the engine was warm.
I visited the workshop and asked them to quickly replace the faulty hydraulic component. Turns out, it was a leaking main bearing! Upon closer inspection of the oil, tiny metal shavings were also visible.

Hi,

First of all, I'm sorry for my delayed feedback. I haven't been able to find the time to browse the internet much lately.

I had the timing belt replaced about 5,000 km ago, and I only decided to replace the hydraulic lifters later. Excessive wear on the crankshaft or the lifters was not actually visible.
The entire process took 1.5 hours and went completely smoothly.


Next up, the fuel injectors need to be replaced; he's definitely earned that with the mileage he's put on it.

Greetings.
Okay, here's the translation:

Achim.