Ticking/Knocking Noise in VW Golf Engine (G 4 ARL)

I'm sorry to be posting again, but I can't seem to find my previous post, and I didn't receive any feedback on it.

The vehicle is a Golf 4 ARL 4-Motion with 205,000 km on the odometer.

I hear a ticking or knocking sound in the engine compartment, both while driving and while idling.
In my opinion, it sounds metallic, but I'm not 100% sure.
I've managed to locate the source of the smell, and I've attached two pictures to show you.
I'm ruling out the PD unit because I checked it using VAG diagnostics, and there are no differences between the units, nor do they deviate from the specified values.

Could it be due to a worn camshaft?

Best regards,
Thilo

Why would the tandem pump make a ticking sound if the cam is worn?

However, the pump is driven by the camshaft, and there might be an issue with the gears in that area. I suspect you'll need to open it up, meaning you'll have to remove the valve cover, to see the camshaft and the pump drive.

m;

First of all, thank you. I unfortunately didn't know what that part was.

"Are there any specific things I should pay attention to when it comes to the threads or the tandem pump?"

Could the tandem pump fail and damage the PDE (pump-injector-control module) because of a lack of lubrication?

Regards,


EDIT:
After a brief disassembly of the valve cover, I have to agree with Dieselmartin: the camshaft doesn't show any signs of wear, not even the slightest. I think that's quite good for over 200,000 km.

Unfortunately, I couldn't see the interlocking mechanism --> no luck. Maybe I misunderstood you, and you want me to also remove the timing pump.
By the way, the valve cover can remain in place while you unscrew the pump.
I'm not entirely sure how it's constructed, and there might be some imperfections or blemishes.

klahaui wrote:

Could the tandem pump fail and damage the PDE (pump-injector-control module) because of a lack of lubrication?

"Not at all. If the fuel supply is insufficient, the engine will exhibit performance issues. For example, it might jerk during acceleration. If it doesn't receive any fuel at all, it won't run."

On the drive wheel of the pump, there is a ridge, and on the opposite side, there is a recess. I hope we have a tandem pump in stock, and I'll try to send you a picture later. However, I won't be able to upload it until tomorrow at the earliest. When installing a tandem pump, make sure that the ridge fits into the recess.

Google and the forum are aware of this.

Okay, I'm ready. Please provide the German text you want me to translate.

Martin's link is pretty good, thanks for sharing it.

I think Steffen's description is very good.
It would mean, in German: "You can drive with it until it starts to sputter or stall."

I will continue to monitor the situation and keep an eye on it. Also, I would still appreciate a picture from Steffen.
I can observe the prices for a pump, and maybe I'll find a bargain sometime .

You're very welcome.
Best regards, Thilo.

Here are a few more things that came to mind regarding that time period.
What is this supposed to produce? The interlocking mechanism doesn't seem quite right to me.
It sounds to me more like the clicking of a valve, and the faster the engine speed, the more frequently it clicks.
I find it somewhat questionable, as the engine seems to be a bit louder when it's warm. It could, of course, just be a feeling.

klahaui wrote:

It would mean, in German: "You can drive with it until it starts to sputter or stall."

It's a tandem pump that not only supplies fuel but also generates a vacuum. You can check its internal tightness and fuel pressure with the appropriate equipment if you encounter any problems. The tightness towards the cylinder head is another issue, as you have probably already read.
Don't worry about the PDE (positive electrode displacement) pump; the engine will stall beforehand due to fuel starvation.
Unfortunately, we didn't have a pump available yesterday, but in the thread that Martin linked, there's a picture showing what that bridge looks like.
Is the noise also present when the engine is idling? If so, you could use a stethoscope or a screwdriver held against the engine to pinpoint whether the ticking sound is coming from the pump or not.

Yes, the device is also powered on, and I was able to locate the device using a screwdriver.
Today, I noticed a loud, metallic clattering sound under the valve cover, which becomes even more noticeable when I open the oil filler cap.

What is the vacuum generated by the tandem pump used for?

Greetings.

The vacuum generated by the tandem pump is used to operate components such as the AGR valve, the VTG control for the turbocharger, the shut-off valve, and so on.

So, does that mean that if the tandem pump starts to fail more, I would also experience less power and/or the turbo would engage later?

I'm starting to have doubts that it's actually the tandem pump.
While I hear a loud ticking sound when I put the screwdriver on it, the ticking sound coming from the engine compartment is definitely higher-pitched. Based on the speed, it's definitely related to the low-speed engine RPM.
That might not be suitable for so many parts, right?

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

"MFG" is an abbreviation for "Mit freundlichen Grüßen," which means "Sincerely" or "Best regards" in English.

Hi, my ARL engine was also making a lot of ticking noises recently. I think it was a lifter that wasn't getting enough oil. But after that drive, it hasn't happened again.

Unfortunately, I always seem to...
Even after driving 100 km, whether in electric mode or when accelerating.

It doesn't really sound like hydraulic lifter noise.

Today, it was gone. The outside temperature was 3°C, and there was absolutely no rattling or any other noise.
Let's see how I'll feel after riding 50km.

Since my "knocking" (presumably referring to a physical or emotional issue) has been resolved through therapeutic touch,
"I'm now facing the problem that it occasionally starts to stutter or jerk, especially under partial load."
It only happens when I accelerate gently, and so far, only at low RPMs.

Now, I'd like to find out, with your help, if the problem is really due to the tandem pump.
Could you tell me which log file I should provide so that you might be able to identify the issue?
I would be very grateful for your help, and I hope that we can resolve the problem so that I can continue to enjoy my car for a long time, without ever having to stop because of a lack of fuel .

Best regards, Thilo.

Hi, it's probably not the tandem pump; it's relatively simple in design and doesn't have to do any heavy mechanical work. It has an eccentrically adjustable drive shaft, which definitely shouldn't make any noise with the mileage you've put on it. At most, it might leak externally. I'll take a picture of the pump and the drive shaft tomorrow.