Noise, vibrations, ticking sound high rpm

[Staljin]

Hi,

I have A4 B6 TDI PD 74KW AVB engine. Have problem with noise, ticking sound and strong vibrations on high rpm 2500 and over. Noise is progressive and increases with rpm. Sometimes it makes deep rumbling sound at low rpm.

I made a video when stationary.

https://youtube.com/shorts/9z_IRxbZJbw?si=WTID32kaz_NQ5_G5

I am thinking hydraulic lifters and cam. But should that give so strong vibrations. I did remove valve cover and tried pushing lifter with screwdriver. There is a play of 1+ mm on depressed lifter. Checked only one.

Cam do not have any hard wear but there is a longitudinal discoloration on both side ends of some cams.

Any idea what could be the cause? I would like to avoid pulling engine out.

Rebuild of cylinder head is not a problem.

Staljin

[Staljin]

Some more info. There is also progressive rythmic clicking noise at 2500rpm plus when I let go of gas pedal. When I let RPM go down from 3500rpm to 1500rpm I get shaking for a 1-2 seconds at about 2500-ish.

Both drive shafts are new. Turbo is new. Gearbox replaced newly but I had to move output flanges from old gearbox.

Whole suspenstion is renewed in last 2-3 years. Steering rack and all hoses are new. Serpentine belt is new. Car is tuned a bit. I would say up to 140-is HP

VCDS show no engine faults.

Checked camshaft an there seem to be no obvious wear.

This knocking has been present for quite some time and is getting worse.

Any idea what could be the cause of this knocking?
Staljin

[Staljin]

No power loss. Some blow by but no oil level loss. Timing belt replaced 4 years ago.

[Mike Tries]

Rod bearings? Open an oil filter and check the filter pleats for metal. It might just look slightly glittery. If you have glittery oil, your engine is eating itself.

[Staljin]

Tx. Will do that.

[Staljin]

I finally got it done. No metal debris in oil filter of any kind. Did not change filter last time I changed oil so filter is about 1.5 years old. Found just a really small piece of plastic.

Forgot to mention that fuel economy has actually never been better. 6.3l per 100km mostly short drives in town.

I am stuck.

[Staljin]

https://ibb.co/jZjDKbnp

[willemml]

That fuel economy sounds unrealistic for driving around town. Just my opinion. What does VCDS say your fuel trims are?

[Mike Tries]

What color is the plastic? There shouldn't be any plastic in there. Plastic debris could be the pads of the timing chain adjuster shredding themselves.

[Staljin]

Thank you for answer. Its a small black piece.
https://i.postimg.cc/pdSKfvxq/IMG-20250608-194457.jpg

[Staljin]

That fuel economy sounds unrealistic for driving around town. Just my opinion. What does VCDS say your fuel trims are?

I did not do any logging lately. Torsion timing dances between 0 an 0.5°. Channel 32 is not available so no fuel trim reading.

Consumption should be real from full tank 1002km and 63.7l diesel filled.

[Staljin]

Lobe 1 or whatever it is called has some scratches than can caught nail.

https://i.postimg.cc/7P9YdVJy/i-Mark...607-150422.jpg

I do not know if it has anything to say but first compartment of 4 where injectors are located is full of engine oil while the rest 3 are empty

https://i.postimg.cc/T2tfC3Bd/i-Mark...607-151123.jpg

Can these residual oil indicate lubrication problem?

[Staljin]

I forgot to mention that noise, clicking, vibrations are strongest when decelarating.

[Mike Tries]

Oh, right, it's a TDI. I forgot about that part. Still, if I was trying to figure this out and I had the engine at-hand, I'd be trying to figure out where the plastic inside the oil filter came from.

[Staljin]

Tx for answer. I am leaning toward oil pump chain tensioner. It is made of plastic. No warning about low oil pressure on dashbord though.

[Mike Tries]

OK, so if that failed, could the noise be the oil pump chain rattling around? Can you see the chain somehow to see if it's loose? Maybe you can borescope it through the oil drain hole.

[willemml]

I also missed that it was a diesel, hence my doubts around fuel economy. Definitely inspect anything, just because there is no oil pressure warning doesn't mean that oil pressure is low in some parts of the engine, some places not getting oil makes me wonder if the pieces of plastic are blocking some passages. Definitely inspect anything you suspect being broken and see how much more plastic might be in the engine.

[Staljin]

OK, so if that failed, could the noise be the oil pump chain rattling around? Can you see the chain somehow to see if it's loose? Maybe you can borescope it through the oil drain hole.

Unfortunately I can not se chain. Oil pan had to be removed to gain access to oil pump and chain. Removing oil pan involves lowering subframe. I can do it as I did it before when I had to replace gearbox.

[Staljin]

I also missed that it was a diesel, hence my doubts around fuel economy. Definitely inspect anything, just because there is no oil pressure warning doesn't mean that oil pressure is low in some parts of the engine, some places not getting oil makes me wonder if the pieces of plastic are blocking some passages. Definitely inspect anything you suspect being broken and see how much more plastic might be in the engine.

I am also wondering if some parts of engine are not getting oil. Why there is oil in only one of 4 injectors compartments? I do not know how it should be and what that difference eventually mens.