Audi A6: Intermittent Smoke After Turbo Replacement

Hello specialists,

On my A6 Avant quattro with Tiptronic transmission (manufactured in March 1999), with engine code AFB and 142,000 km on the odometer, the defective turbocharger was replaced with a new one approximately 2 weeks ago.

Subsequently, the performance (and also the smoke when accelerating hard) was back to normal.

Now, I've noticed that when the engine is warm and I release the accelerator pedal, the car occasionally emits a blue smoke cloud. This lasts for a few seconds and then disappears. If I give it gas while it's smoking, it disappears (for the duration of the acceleration). }

As I mentioned, the error occurs sporadically (e.g., once every 5-10 km); the performance, noise, and fuel consumption are normal; I've already taken it to the dealer twice (they only adjusted the fuel injection pump, which was also replaced 9 months ago - no change), and they're also at a loss.

Could it be that oil that entered the exhaust system due to turbo damage is still being 'after-burned' (the dealer said they cleaned the exhaust manifolds after replacing the turbo)? }

I would be grateful for any feedback.

Roman.

BTW: Is there a schematic diagram of the AFB engine (with all the solenoid valves, etc.) available anywhere online?

Hello,

rwambacher wrote:

Hello specialists, On my A6 Avant quattro with Tiptronic transmission (manufactured in March 1999) and engine code AFB (142,000 km), the defective turbocharger was replaced with a new one approximately 2 weeks ago. Subsequently, the performance (and also the smoke when accelerating hard) was back to normal.

If that wasn't the case before the repair, here are 3 things that come to mind:
- Issues with the crankcase ventilation system; the search function finds several results related to this topic.
- How did the old turbocharger fail? Could any fragments have damaged the cylinder walls or valves/valve guides?
- Errors during repair. Dirt in the injector lines, incorrect valve timing, etc.

rwambacher wrote:

Now, I've noticed that when the engine is warm and I release the accelerator pedal, the car occasionally "lets out" a blue smoke cloud. This lasts for a few seconds and then disappears. If I give it gas while it's smoking, it disappears (for the duration of the acceleration).

As I mentioned, the error occurs sporadically (e.g., once every 5-10 kilometers); the performance, noise, and fuel consumption are normal; I've already taken it to the dealer twice (they only adjusted the fuel injection pump, which was also replaced 9 months ago - no change), and they're also at a loss.

Could it be that oil that entered the exhaust system due to turbo damage is still being "afterburned" (the dealer mentioned that they had cleaned the exhaust manifolds after the turbo was replaced)? }

I would be grateful for any feedback.

Roman.

BTW: Is there a schematic diagram of the AFB engine (with all the solenoid valves, etc...)} available anywhere online?
If there was no blue smoke before the repair, I believe the workshop has a responsibility to fix the issue properly.

The new turbocharger might have been installed incorrectly, which could have already caused significant damage (e.g., by applying full throttle immediately after installation, without proper priming with engine oil, and without waiting for the engine to establish normal oil flow).
Ebenso kann die Abdichtung des 'neuen' Laders defekt sein. Ist er denn wirklich 'neu'? Check!

Best regards, Rainer.

If that wasn't the case before the repair, here are 3 things that come to mind:
- Issues with the crankcase ventilation system; the search function finds several results related to this topic.
- How did the old turbocharger fail? Could any fragments have damaged the cylinder walls or valves/valve guides?
- Errors during repair. Dirt in the injector lines, incorrect timing, etc.


Before the repair (and also blue), it was smoking because the turbo was faulty (apparently, oil was leaking through the defective turbo into the system).


If there was no blue smoke before the repair, I believe the workshop has a responsibility to fix the issue properly.

The new turbocharger might have been installed incorrectly, which could have already caused significant damage (e.g., by applying full throttle immediately after installation, without proper priming with engine oil, and without waiting for the engine to establish normal oil flow).
Ebenso kann die Abdichtung des 'neuen' Laders defekt sein. Ist er denn wirklich 'neu'? Check!


'These are good starting points... I have an appointment at the workshop next week... let's see what the mechanic thinks... and how the old turbo failed.'

Thank you very much in the meantime!

Regards,


Roman.

Hello.

Quote:

Before the repair (which was also blue), it was smoking because the turbo was broken (apparently, oil was leaking through the defective turbo into the system).

Oh oh... I hope this trade was worth it...

Take a look around the forum (use the search function); I mean, there was a problem with the crankcase ventilation system with this engine.

As often happens, the great AFB engine...


The problem manifests as excessive crankcase pressure, which in turn leads to increased oil consumption and blue smoke.

Best regards, Rainer.

Hello,

Here's also a common error that occurs with the AFB:

The vehicle has a very high oil consumption, and there are no visible external leaks.
Blue smoke from the exhaust system.

Cause.
Defective check valve in the oil filter module. This prevents the engine oil from flowing back into the oil pan and causes it to be burned off through the intake manifold.

The error persists until week 20 of the year 2000.

I think I'm going to put together a complete package for the AFB. It's really starting to make sense financially.

So, today was another one of those days that I'm really embarrassed about...

Highway: 140 km/h.

Cruise control engaged: all systems nominal.

off the gas: the car is emitting a blue cloud, making it seem like fog has rolled in (at least now the people behind me are keeping a safe distance... ).

It doesn't happen every time, but it's quite frequent today (especially during city driving and when idling at a red light).

Let's see how the oil filter module and the venting system are doing.

Roman.

Okay, so the car was now in the workshop for its major service.

I pointed out to the workshop manager that there might be a problem with the crankcase ventilation system, but he just said, 'That's not something that happens with this type of engine.'


Anyway... supposedly they only changed the filters; since then, the smoking issue has disappeared, and the car is running smoothly again.

They didn't even calculate the working hours for the ENTIRE service team (and the last EP hire)... not bad.

Sure, here's the translation:

'Best regards,' or 'Sincerely,'.

Roman.

I pointed out to the workshop manager that there might be something wrong with the crankcase ventilation system; he just said, 'That doesn't exist on this engine.'
aaaahhh yes


Even the working hours of the ENTIRE service (and that of the last EP hire) were not calculated.... not bad.
Hmm... that sounds like guilt to me.

CU Gremlin.

Okay, so... the car ran well for about 2 weeks after the service (without any smoking), but then it started exhibiting the problem again, intermittently.

So... I went to A DIFFERENT workshop and had the crankcase pressure measured... and sure enough, the pressure was beyond the measurement range of the mbar instrument.

So, it seems there is a problem with the venting after all.


Okay, here's the question for the experts: Which part (oil filter housing, pressure relief valve components, connection fitting for the oil separator) could be defective? (The nice gentleman didn't explain it in detail... he just said he wanted to replace a filter and that it would take about 3 hours of work).

Thank you very much for your help.

Roman.

At least you now have a nice new loader .

Okay, here's the question for the experts: Which part (oil filter housing, parts of the pressure regulating valve, connection fitting for the oil bypass) could be defective? (The nice gentleman didn't explain it in detail... he just said he wanted to replace a filter and that it would take about 3 hours).



Replace the entire module with the one from the 132kW TDI engine. This one no longer has a filter, but instead consists of three small cyclone separators. The exhaust gases are 99% oil-free, so nothing can clog it!

Regards,

Manuel.

Hello everyone,

I'm following this thread with great interest, and I'm very eager to learn whether and how the problem has been resolved, as I'm experiencing a similar issue myself.

It would be very helpful if the person involved could contribute a brief update to the status.

Best regards,
The clumsy person
PS: Very nice and competent community, keep up the good work.

Ultimately, the oil mist separator in my AFB was replaced because it was apparently clogged, which caused the pressure relief valve to periodically open towards the exhaust system.

After the exchange (autumn 2003), everything has been fine ever since (except for the gas struts on the trunk, which are a different story... ).

Sure, here's the translation:

'Best regards,' or 'Sincerely,'.

Roman.