Abgaskrümmer | Posts 16+

dokky wrote:

So prematurely happy. After a week and 2000 km, this morning, right after starting, it made a brief whistling sound from the engine compartment. Then, while waiting at a red light today, I smelled something again coming from the ventilation system. I opened the cover, and it smells bad again at the first cylinder. Could the head be warped? I can rule out the DPF and catalytic converter, the engine is running at its maximum speed.

No, it's more likely that the exhaust manifold is warped again. This is probably due to the casting material, which causes the same problem in many Fiat engines.
Are you sure the DPF isn't full and constantly regenerating?

Hi,

It's not even an original part, and it looks much more stable.
The DPF has regenerated once.

Errors in all files.

Buying an Audi, Seat, Skoda, or VW, I wouldn't know of any diesel models that have such problems.
There are other options for that.
You can at least use VCDS to monitor the exhaust gas temperature, and perhaps your car also has that capability. At least for most 2.0 TDIs, the exhaust gas temperature limit is around 820°C.

What does the valve control do? Could the valve timing be off, or are the valve tappets/lifters worn, resulting in insufficient air entering the cylinder?
I've seen this happen in various engines with clogged intake manifolds - they get very hot very quickly under load.

EDIT: There might be a stainless steel exhaust bend from the motorsports or tuning industry that can withstand higher temperatures better than the cheap cast iron part.

I would only grind off the manifold in the areas where it bulges, perhaps creating a slight 2 mm concave shape that would flatten out again under hot operating conditions.
But the cause is either the head or the temperature.

Hello!

I've had warped exhaust manifolds before (mostly on gasoline engines, but also on T3 diesel engines).
"If they weren't cracked, I had them milled flat at a machine shop in the neighboring town. He can't grind them (it's difficult to clamp manifolds securely), but if he mills them at a high speed with a slow feed rate, the surface is okay, and it works fine."

I also read that once a manifold is warped, it won't straighten out again.
That also aligns with my long-standing experience.

Furthermore, there's another issue: sometimes the studs in the head break off, or sometimes the threads become partially stripped due to the forces exerted during warping.
This should also be considered, checked, and, if necessary, corrected.

Hi,

Even a planned exhaust manifold can warp. A fault was also found, the DPF was almost clogged, and the differential pressure sensor was defective, which is why there was no message from the engine control unit. A new DPF was installed from the internet, the exhaust manifold was replaced with a new gasket, and lo and behold, everything is now quiet.

The car has also been sold, and now there's a VW parked outside.

Thank you for the feedback!

So, it got too hot after all.