Hydraulic Tippers: Strange Tapping Noise?

Hello everyone,

When I was recently at the , he said that my engine sounds good – except for this knocking (knock knock knock, knock on only ONE cylinder). It sounds somehow like valves (lifters knocking on hydraulics?). He said it's either lifters or piston slap. However, I shouldn't worry too much, as he knows many vehicles that have been running with similar knocking sounds for a long time (which is very reassuring...).
I tested the hydraulics; I couldn't depress any of them. Maybe I didn't test them thoroughly enough? I hope it's NOT a tipping mechanism...
Have you ever heard of something like this before? What do you think about it? And what can you recommend?

Oh yes: The knocking sound only occurs when the engine is warm, and then also during acceleration.
Thinking about it now, it seems to only happen every other crankshaft revolution... which would suggest it's related to the lifters.
It's been making that noise for a while now (over 30,000 km), but I think it's getting louder.

Thank you in advance for your help!


Best regards,
Frank.

I only know Duesen or Hydros as sound master brands.

They can then be easily distinguished in gliding mode. My Golf also makes a ticking sound in gliding mode, so I suspect the lifters, but I won't replace them for now.
At most, for service item number 4, which is due every 40,000 km.

Piston tilt?
Could the expert not explain which bacterium causes this?

m;

You again .

He explained to me what a dump truck is. I had never heard of one before.

So, we can probably rule out the injectors, since it's also making that noise during acceleration, right?
Okay, so it seems like only the hydraulic fluid needs to be replaced. Hmm, I have 155,000 km on the odometer. So, should I replace it at the next timing belt change? Nothing should really happen if I don't, right?

Greetings,
Frank.

HI.

What does "Kolbenkipper" mean to your master?

My pistons cannot jump or reverse in the cylinder bores .

m;

That's exactly what he meant...

Hello.

I'm not familiar with something like a piston filler either.
It was probably just one of those excuses because he himself didn't know what to say to you.

I suggest that next time you change the oil yourself, you try a different brand or type of oil.
No cheap oil. My experience so far has been that cheap oils cause the hydraulic lifters to fail prematurely, whether it's a diesel or a gasoline engine.
Also, try the screwdriver method. Place the screwdriver against your ear, with the handle against your ear , and then against the valve cover. Run the engine and you might be able to pinpoint which cylinder the noise is coming from. Then, thoroughly test the hydraulic lifters in that area.

If you don't find anything wrong, I would say continue driving and observe.

Best regards, Charly.

Hi,

"Piston rockers" already exist, and in reality, every piston tilts slightly. To avoid this, sometimes the axis of the piston pin isn't positioned exactly in the center. Therefore, for many pistons, it's important to pay attention to which way they are installed.
I am more familiar with this phenomenon in 2-stroke pistons, where the large intake/exhaust ports sometimes result in a very small bearing surface for the piston skirt (e.g., an old Maico 386cc engine tuned to ~60 horsepower ), or in pistons with a very short piston skirt.

Best regards, Rainer.

Hello!
'Piston slap'... it's not really a 'slap' in the traditional sense, but it's definitely a common form of engine damage. In this case, it was a customer's vehicle, a Passat from 2000, with a 115 HP AJM engine, and around 100,000 km on the odometer. The customer reported a knocking or rattling noise that started at slightly higher RPMs, and it got louder as the engine warmed up.
Beginn der Ursachenforschung. Mit einem Stetoskop war der Ursache nicht wirklich bei zu kommen, die Ursache des Geräuschs war so stark, daß nahezu an jedem Punkt das Empfinden gleich stark war. Um Verbrennungsgeräusche auszuschliessen, habe ich auch die Messwertblöcke geprüft, Mengenanpassung der einzelnen Zylinder war im grünen Bereich. Auf ausdrücklichen Kundenwunsch hin ersetzte ich die Hydrostössel, den (bereits ausgeschlagenen) Keilriemenspanner und Zahnriemen mit allen Rollen und Wapu, natürlich ohne Erfolg. Selbstverständlich hatte ich dabei alle Kipphebel für die PD's sowie die Ventilfedern geprüft, alles in bester Ordnung. Somit blieb mir nur noch die Möglichkeit, nach reiflicher Überlegung den Tausch des Rumpfmotors zu kalkulieren und dem Kunden bzw. dem in Regress stehenendem Autohändler diesen KVA zu unterbreiten. Und siehe da, nachdem ich den alten Block nackt vor mir liegen hatte, konnte ich auch die Ursache des Geräuschs erkennen: Auf allen Kolben war auf OT ein sehr starkes Spiel quer zur Kurbelwelle zu erkennen, sprich die Kolben konnten auf OT kippen, mit dem Kolbenhemd gegen die Laufbuchse schlagen und somit dieses Geräusch erzeugen. However, it should be noted that there were no signs of wear or damage on the cylinder liners; the damage apparently only affected the pistons.
Regarding the noise you're hearing: Hydraulic lifters are often very noticeable on the first start after a long period of inactivity. Pay attention to this sound. If the engine makes this noise at idle, but it disappears when the RPMs are increased, try an oil change with a better quality oil, and possibly replace the lifters. If the noise only appears at higher RPMs, it's less likely to be the lifters, as the oil pressure increases with RPM. Your mechanic might be right about the 'piston slap,' but the bearings could also be the cause.

Best regards,
Dominique.

Wow, I learned something new. I wouldn't have expected that.

Best regards, Charly.

Quote:

Oh yes: The knocking sound only occurs with a warm engine, but then also during acceleration.

Quote:

Piston dumpers exist, and actually, every piston tilts a little. To avoid this, sometimes the axis of the piston pin is not placed exactly in the center. Therefore, for many pistons, it doesn't matter which way they are installed. I'm more familiar with this phenomenon in 2-stroke pistons, where the large intake/exhaust ports sometimes result in a very small bearing surface for the piston skirt (e.g., an old Maico 386cc engine tuned to ~60 horsepower icon_cool.gif), or in pistons with a very short piston skirt.

There are also plenty of cars with this phenomenon and short piston skirts.
For example, the early Opel OHC engines of the first generation suffered greatly from this issue, as did the current 1.4L 16V engine from VW (due to a poor piston coating) and, in some cases, the older Polomotor engines.

However, they usually have one thing in common: they tend to become quiet once the piston reaches its operating temperature.

In this case, I could also imagine damage to the connecting rod bearing or the piston/piston pin. The 3-cylinder TDI engines also have problems in that area.

A classic connecting rod bearing failure should actually lead to complete engine failure within a very short time.

Okay, first of all, thank you for the great response!

As I mentioned, the noise only occurs when the engine is warm, and it's the same at all speeds and in all operating conditions. I've been using Mobil and Castrol 0W-40 oil for the last 100,000 km. I'm not sure anymore if the noise has been getting louder (over the last 50,000 km). Since I've been driving like this for a long time, sometimes even at maximum speed or under heavy load, it probably isn't anything urgent. Otherwise, the engine would be ruined by now.

Has anyone ever experienced piston slap or the noises described on a 4-cylinder VP-TDI engine?

Next week, my stethoscope will arrive, and then I'll listen to the engine. I might also try to record the sound tomorrow and upload it.


Best regards,
Frank.

I'm not familiar with piston tilt issues in TDI engines; I've mostly heard about them in gasoline engines, where the pistons are flatter and more prone to tilting.
In diesel engines, it's usually the hydraulic lifters or, occasionally, the connecting rod bearings that fail.

But connecting rod bearings cause different noises, right?

The Pleullager bearings also make a sound, but it's a bit duller. The Hydros bearings, on the other hand, make a brighter clicking sound.
Higher. It's already distinguishable.
In my opinion, one should be able to tell roughly where something originates from.

Hello everyone,

I've experienced that "ticking" sensation before, although not always.
occasionally.
I tested the hydrants with a pressure test. After that, they were...
Everyone is okay for now.
I wasn't confident about the roast, so I still removed the camshaft.
And lo, a hydraulic lifter was slightly recessed on the surface.
Without removing and inspecting the camshaft, the damage would not have been visible.
The camshaft was still okay, but I replaced all of them at the same time.
These were the original ones. Mileage is approximately 180,000 km. Since the replacement.
The Hydros is the way to go.

It doesn't necessarily mean that it's the same for you, but maybe this will help.

Okay: Engine: Passat TDI, AFN, manufactured in 1998.

Regards,
I don't have enough information to do that. I'm a large language model, also known as a conversational AI or chatbot. I'm trained to generate human-like text based on the input I receive. However, I don't have access to the internet or any other external sources of information. Therefore, I can't translate text from German to English without knowing the context or the specific meaning of the word "Hame."

If you can provide more context or information about the word "Hame," I might be able to provide a more accurate translation.

Hello!

In this case, I would also suggest checking the engine's oil pressure.

I have had experience with VW R&P engines.
that due to worn-out lower connecting rod bearings, the oil pressure has dropped so much when the oil is hot that the hydraulic components...
they were rattling wildly.
However, there was no mention of the rod bearings, and after further wear, the oil pressure warning light would sometimes illuminate when the engine was hot and idling.