Broken 1.9 TDI AFN Camshaft: Causes & Fixes

Hi,
It's been a while, I'm back again.
Unfortunately, the reason for this is rather unpleasant: the AFN (automatic fuel mixture control) in my T3 has failed.
The camshaft is broken on cylinder 1.
The bearing surface shows significant wear, and the camshaft lobes are extremely dry. However, the other three cylinders are properly lubricated.
The oil pressure was good at the time of the incident, more than 5 bar.
However, the pressure sensor (pressure capsule) is located on cylinder 4, which is directly opposite.
Timing belt, etc. are all in excellent condition.
Has anyone ever experienced something like this before?

Regards,
Jens.

Hi,

Quote:

The oil pressure was also good at the moment of the incident, more than 5 bar. The measurement point (pressure sensor) is located on cylinder 4, so directly opposite.

Theory: What if a hydraulic lifter became over-pressurized (due to high oil pressure and dirt in the inlet valve) and the camshaft forced the valve to hit a hard stop (valve contacts the piston)?

Given the age and mileage (?), or the damaged bearing(?), a fatigue fracture is also a possibility. The NW (presumably a component) is certainly not the weakest link in the chain if a valve sticks.
If the bearing had a lot of play (which is why?), it will naturally swing more within that range.
hg
Herbert.

Okay, I disassembled the engine quite some time ago, and unfortunately, I had to conclude that there was no oil pressure. Neither the oil pressure gauge nor the oil pressure switch were working correctly. However, I haven't yet figured out why there wasn't enough oil reaching the cylinder head. The oil pump looks completely normal, and the engine block itself doesn't show any signs of oil starvation, at least not visually. It's not easy to determine because several valves abruptly stopped two pistons during their upward movement.
The engine is in such poor mechanical condition that it's essentially scrap, and it's not worth repairing.

Low oil pressure can be caused by a pump that isn't generating enough pressure, or by a lack of counter-pressure due to wear.

The rear bearing of the intermediate shaft is a common failure point in these engines.