Oil Consumption: Blue Smoke, Leaf Valve?

Hello, I've recently noticed a high oil consumption, about 1 liter per 1000 kilometers.
I usually only have to refill it once between changes.
I haven't lost a single drop.
I'm having a hard time believing the explanation about the shaft seals, as it seems to have happened suddenly.
I haven't experienced any loss of power either.
Now I've heard that the leaf-spring valve in the oil filter can cause high fuel consumption if it's defective.
Does anyone have any experience with that?
Can the filter be replaced individually, or does the entire oil filter housing need to be replaced?
Does anyone know the price?
"I've also noticed something else: when I check the oil level about 5 minutes after the engine is turned off, it's okay. But overnight, it's above the maximum level. This probably means that the oil filter housing is emptying?"
That definitely wasn't the case before.
Audi A6 2.5 TDI Quattro, AFB engine, 55/99.
I would appreciate help .
Thank you. Best regards.

A6 Andreas wrote:

Hello, I've recently been experiencing high oil consumption, about 1 liter per 1000 kilometers. I usually only have to refill it once between changes. I haven't lost a single drop. I'm having a hard time believing the explanation about the shaft seals, as it seems to have happened suddenly. I haven't experienced any loss of power either. Now I've heard that the anti-drain valve in the oil filter can cause high fuel consumption if it's defective. Does anyone have any experience with that? Can the filter be replaced individually, or does the entire oil filter housing need to be replaced? Does anyone know the price? "I've also noticed something else: when I check the oil level about 5 minutes after the engine is turned off, it's okay. But overnight, it's above the maximum level. This probably means that the oil filter housing is emptying?" Wasn't that definitely not the case before? Audi A6 2.5 TDI Quattro, AFB engine, 55/99. I would appreciate help . Thank you. Best regards

.

Hello A6 Andreas,

It's new to me that a regular oil filter could affect oil consumption, and I find it very unlikely.
I'm leaning more towards the turbocharger, which, unfortunately, would be quite common for a vehicle manufactured in 1999.

A more common issue is a blocked crankcase ventilation system, which some workshops replace along with the oil filter module, where the leaf spring valve is located. Measure the crankcase pressure inside; the maximum should be 5 mBar. Use the replacement part ("seal kit") from the AKE (air cooler element) as a substitute.

Hello, and thank you for the quick responses.
One of the turbochargers has approximately 20,000 kilometers (about 12,400 miles) on it, and the oil separator (or whatever it's called) was also replaced at the same time.
I took off the hose from the air intake a little while ago, and it's full of oil (the inside wall).
I think I probably have to replace the entire module!
It doesn't exactly look cheap.
Do you know the price, Christians?
Is there a way to test it?
Before the turbo, there's also an oil puddle in front of the impeller.
I think the crankcase pressure is low because I can leave the oil filler cap open without any issues. Even when I accelerate, it doesn't move.
If it were a leak from the turbocharger, wouldn't there be a puddle in front of it? Right?


Best regards,

"Mine also has a small puddle, but it doesn't require any significant amount of oil."
I believe the price was significantly over €100.

A6 Andreas wrote:

Hello, and thank you very much for the quick responses. One of the turbochargers has approximately 20,000 kilometers on it, and the oil pan was also replaced at the same time, along with what's called the cyclone separator. I took off the hose from the air intake a little while ago, and it's full of oil (the inside wall). I think I probably have to replace the entire module! It doesn't exactly look cheap. Do you know the price, Christians? Is there a way to test it? Before the turbo, there's also an oil puddle in front of the impeller. I think the crankcase pressure is low because I can leave the oil filler cap open without any issues. Even when I accelerate, it doesn't move. If it were a leak from the turbocharger, wouldn't there be a puddle in front of it? Right? Regards

One could try removing the spark plugs. With a high oil consumption, something should be visible if a piston is pumping oil, etc. This way, the oil consumption might be narrowed down to a specific cylinder.

Hello Steffarn,
I don't want to rely on the hope that the piston is pumping oil.
Since my intercooler hoses are oily, I hope it's the leaf spring valve.
I received the membranes yesterday and will replace them today, including the oil return valves.
While they aren't defective yet, I'm replacing them as a precaution, since replacing the oil filter housing isn't a quick job either.
Best regards,

After driving for two weeks, I noticed that there is no more oil consumption.
The butterfly valve was okay.
I installed the cyclone separator during the process.
I assume that oil was sucked into the old K-G ventilation system.
The two trimmers are completely different in their design.
I can imagine that when oil seeps through the filter/flow restrictor...
Oil can be sucked in.
I'm assuming that I haven't damaged my cats yet.
Best regards,

Okay, that's something. I thought you already had a cyclone separator. You can tell if the cat filter is still working, or rather, you won't smell anything if it is.

Quote:

Hello, and thank you very much for the quick responses. One of the turbochargers has approximately 20,000 kilometers (about 12,400 miles) on it, and the oil separator (or whatever it's called) was also replaced at the same time. I took off the hose from the airbox earlier, and it's full of oil (the inside wall).

Above, you wrote that the cyclone separator had been replaced.
Actually, a defective oil separator should have been detected due to the excessively high crankcase pressure.

Yes, I was also very surprised that the old thing was still inside.
I was told back then that it was the new one.
However, the pressure in the system was not too high.
The old oil separator absorbs the oil fumes in a completely different way compared to the new one.
It's a completely different principle.
The salesperson initially didn't want to sell me the cyclone separator.
It doesn't fit there, not even starting from 2001.
That's nonsense, it fits.
Best regards,