Oil Leak: AFN/Turbo Exhaust Problems

Hello everyone,

I'm new here and I hope your experience will finally solve my problem.

I have a Volkswagen Golf 3 TDI with the AFN engine, and I've built a GT1749VB turbocharger for it.

Specifically, since the new 1749vb was installed, I've been experiencing significant oil leakage between the turbo and the downpipe.

The oil return line, while not new, has been checked for flow and is not kinked. I have cleaned the crankcase ventilation valve on the valve cover, and it appears to be working properly.

I have a slight vacuum under the oil filler cap.

I'm starting to not know what to do anymore...
I would really appreciate helpful tips.

Sure, here is the translation of the text from German to English:

'Lg' is a German abbreviation that stands for 'Liebe Grüße,' which means 'Best regards' or 'Warm greetings' in English.

I once had a similar issue with an A4 with a PD engine, and in that case, the valve cover (crankcase ventilation) was the cause.

How can I best check this?

"Where exactly is the oil leaking from?"

What is the oil consumption?

Oil is leaking from the area between the turbo exhaust side and the flange of the downpipe, specifically where the triangular gasket should be.

I'd also like to add that the downpipe itself is welded and has a diameter of 2.5 inches.

Regarding oil consumption, I can't really say much because this is my summer car, and I've only driven 100 km since the turbo conversion.

But it's leaking quite a bit, so the steering gear is really oily.

If a large amount of engine oil ends up in the exhaust pipe after the turbocharger, then either the turbocharger is faulty or the turbocharger's oil return line to the oil pan is blocked.

That was also my first thought, but I've already removed the oil return line from the block and briefly started the engine, and a huge amount of oil came out. Also, the turbocharger has been completely rebuilt, and the compressor side, including the compressor wheel, has been upgraded to a BV43 size.

Mk3love wrote:

That was also my first thought, but I already removed the oil return line from the block and briefly started the engine, and a huge amount of oil came out. Also, the turbocharger has been completely rebuilt, and the compressor side, including the compressor wheel, has been upgraded to a BV43 size.

Sorry, what a ridiculous idea. The AFN engine is not really suitable for tuning beyond ~160 horsepower, which makes modifications to a GT1749VB turbocharger unnecessary.
Your funny loader is broken; just read the countless tuning posts about the AFN to learn more about the purpose of your action.