Engine won't start, stalls at traffic lights

Hello, esteemed experts. I'm having a problem with my Golf III Variant, diesel, 55 kW, manufactured in 1994, and I'm hoping for your help.

On a colder day, it was very difficult to start. After a highway drive (80 km), I stopped the car for ten minutes. Then, the same thing happened again. And when slowing down at a traffic light, the engine speed suddenly dropped, and the car stalled several times. After that, it only started again with the 'choke' fully engaged. Also, it has been smoking heavily since these incidents.

What could be the problem, and how can I fix it?

Thank you for the tips.

Best regards, Schnüpp.

Attention: Do not start the process again under any circumstances!
It sounds like the crankshaft pulley has detached, which usually means the valve timing is extremely misaligned, specifically retarded.

Okay, first, check if the crankshaft pulley bolt can be turned. (The bolt is located on the belt side, in the center of the large pulley. It's a 12-point bolt and should be able to be turned with a standard open-end wrench.) However, the bolt should normally be tight enough that it won't budge.

Okay, and just to check, the fifth gear and the handbrake, or the special locking device, which probably isn't there.

If that's the case, my condolences, because that means the timing belt pulley on the crankshaft failed, and it's possible that the pistons and valves have already collided.

Did the engine make a loud, metallic knocking sound at the end?

Once the screw is tightened, check the valve timing.

But even if it's confirmed that the screw is tight and the valve timing is correct, it still won't start. Maybe there's still something we can salvage.

It would also be interesting to know the mileage and whether the timing belt has already been replaced.

And how about it?

Sure, here's the translation:

'I would appreciate feedback.'