T5 2.5 TDI: Exhaust Problems & Solutions

Dear diesel mechanics,

Unfortunately, I haven't been able to find an answer to my problem with the search function, so I'm posting here. Please excuse me if I make any mistakes – I'm new here and not very familiar with this forum. I would be grateful for any helpful guidance.

"The exhaust system on my T5 TDI 2.5L (manufactured in December 2008) has been causing problems for some time now."
Initially, a whistling or blowing sound could be heard during acceleration (not the typical "turbo whine"), while at standstill with the engine running, exhaust fumes were entering the passenger compartment through the ventilation system.
After I discovered that a seal on the turbocharger was broken, I had it replaced. The workshop then noticed that even after replacing the seal, a whistling sound could still be heard, and they subsequently replaced the intercooler as well, which actually had several holes in it (!).

Unfortunately, the problem has not been resolved yet.
-> When accelerating in the 2nd and 3rd gears, there is still a whistling/hissing sound, although it's quieter than before AND...
-> When accelerating, the exhaust pipe emits a significant amount of black smoke (which also leaves noticeable marks on the tailgate), AND...
-> When driving uphill on the highway in 5th or 6th gear, the engine malfunction light frequently comes on, and the engine goes into limp mode.

We are generally very happy with the car and would like to keep it. However, I don't want to replace half or the entire exhaust system without knowing for sure what's wrong. Therefore, I am asking you...
1. to get clues as to what might be causing the described symptoms?
2. to provide the most accurate instructions on how to repair or restore the system.
3. I'm looking for recommendations for a reliable and honest workshop in the Eastern Switzerland region that might be able to help me.

Thank you in advance for any help you can provide.
Markus.

Hi,

Quote:

-> When accelerating in the 2nd and 3rd gears, there is still a whistling/hissing sound audible, although it is quieter than before AND -> When accelerating, the exhaust pipe emits quite a lot of thick black smoke (which also leaves noticeable traces on the tailgate)

.
"That is to say, the air being measured by the mass airflow sensor (MAF) probably isn't reaching the engine, but is instead being blown out somewhere between the turbocharger and the intake manifold. -> Check for leaks, i.e., pressure test the charge air system."

According to my information, the BPC engine has a diesel particulate filter (DPF), so it shouldn't be emitting any smoke from the exhaust. If it is, then either the DPF isn't installed or it's defective.
The engine should not produce any smoke from the exhaust, even if it does not have a DPF (Diesel Particulate Filter).

Best regards, Rainer.

Hello,
A well-known problem with the 5-cylinder engine in the T5 was cracked exhaust manifolds or partially sheared studs holding them in place.
Exhaust fumes inside the car, fluctuating boost pressure, and whistling noises while driving are all signs of a problem.
High indicator of this.

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

"Best regards,
Thilo"

@T5MV0108:

I wrote you an email with a workshop recommendation.