ARL Noises: Troubleshooting Cold Start Issues

Good evening.
I've been experiencing a rattling/tinkling sound in my ARL Leon for quite some time, especially when the engine is cold.

The sound is unfortunately very difficult to describe; it's somewhat like faulty hydraulics, but with a slightly higher-pitched ringing. I've tried recording it several times, but unfortunately, all that can be heard is the diesel engine noise, and the other sound is not discernible.

The noise only occurs when the engine is cold, at an RPM of 2200-2500 RPM. It doesn't happen under light load until the coolant temperature reaches approximately 70 degrees Celsius, and not in full acceleration. If the engine is pre-heated for a long time using the auxiliary heater, the noise doesn't occur at all.

There is nothing saved in the FS.
No irregularities were detected in MWB units 13 and 23 during the warm-up phase.
In general, I couldn't say that I found anything else that could explain it, except perhaps I have 'shrink sleeves' .
I also think it's possible for the elements to have a poor spray pattern.
The camshaft and lifters are in good condition and show no signs of wear.

My dealer just said, 'We need to take the cylinder head off' and then .
'Messen' AHHH yes.

Right now, with the cold weather, I'm starting to get really annoyed with this, and I'd like to turn it off. Do you have any ideas about where else I could look into this?
Thank you in advance.

"How many kilometers are on it? For me, the hydraulic lifters needed to be replaced at around 160,000 km. They weren't making a clanking noise, but rather a ticking/snapping sound. (Not all of them fail at the same time, of course)."

Hi,
What kind of engine oil is being used? Or, to put it another way, do the oil specifications and viscosity match the manufacturer's recommendations?
hg
Herbert.

Currently, I have 130,000 km on the odometer, but I needed a complete engine head replacement at 76,000 km, which cost a fortune .
'If the catalytic converters were defective, I would hear the noise even when preheating the engine with the auxiliary heater. If I don't preheat, I can drive about 4-7 kilometers before the noise becomes audible, but only within that engine speed range of 2200-2500 RPM.'

Regarding the oil: I've always used 5W40 PD oil without the 'longlife' specification from a reputable manufacturer, and I haven't had any problems with it.

Try recording the sound again; then we might be able to assess it better.