Audi A4 8K, year 2008, engine code CAGA - Engine breather hose

I wanted to continue working on the Audi A4 today. The outside temperature was around -7°C.
After driving for about 2 kilometers in the city, it started to smoke and smelled burnt.
I then rode the remaining 2 km home, and after parking and checking the engine oil, I put it in the garage. After that, it stopped smoking.
I initially thought it might be a faulty turbocharger, but the oil level was okay. However, there was an oily substance on the exhaust pipes, which wasn't black, but rather quite light in color.

I then removed the breather hose and a mixture of water, oil, and sludge came out. The same was visible in the intake hose from the air filter to the turbo, starting at the opening of the breather hose. It was also present in the hose before the throttle body.

Is there also a problem with the vent freezing up on these engines?
Where does the oily substance in the exhaust come from?

I must have been in the process of regenerating at the time I was smoking, as the mileage and the time since the last regeneration roughly coincided with when I was smoking.

The car is used almost exclusively for long distances (approximately 50 km twice a day), which is why I'm also surprised to see traces of oil/water in the ventilation hose.

Address 01: Engine Control Module (03L 906 022 B)

13:45:04
007 Air mass; Actual value: 9.69 g/s.
008 Air mass; Target value: 350.5 mg/stroke.
071 Particle filter; differential pressure -3 hPa.
074 Particle filter; kilometers since last regeneration: 6777 km.
075 Particle filter; Differential pressure offset: -5 hPa.
076 Particle filter; Oil ash volume: 0.06 liters.
077 Particle filter; calculated soot mass: 8.01 g.
078 Particle filter; soot mass measured: 5.22 g.
079 Particle filter; Time since last regeneration: 645 seconds.

"Mass flow rate at idle, differential pressure -3 hPa. Even after adjusting the differential pressure sensor, the reading remains the same."

Please check if you are losing any coolant and make sure the oil level is okay.

If the loader receives a sudden surge of liquid during operation, it can damage the compressor impeller.

The images suggest two possible causes based on my initial assessment.
- Primarily drives short distances; the car never warms up properly.
- something is broken.

Best regards, Rainer.

If the engine had been running properly, the oil emulsion would not have been ejected from the exhaust but would have burned off. Please definitely check the condition of the fluids in the oil and water circuits. Both should only contain either oil or coolant, respectively. The information about the type of driving (e.g., short trips) and the general usage profile is also important.

Hi.

Nowadays, the valve cover incorporates a complex system of labyrinths and flaps designed to separate oil from the air stream.

Possibly, they are frozen or broken, causing the MÖL to be ejected in large quantities.

For testing purposes, direct the venting to a separate container.

Better ideas?

Okay, please provide the German text you would like me to translate into English. I will only provide the translation.

dieselschrauber wrote:

Caution, please check if you are losing any coolant and that the oil level is okay. If the loader receives a sudden surge of liquid during operation, it can damage the compressor impeller. The images suggest two possible causes based on my initial assessment. - Primarily drives short distances; the car never warms up properly. - something is broken. Best regards, Rainer

Fluids are okay, both oil and coolant.
I mentioned that the car is used for long-distance driving 98% of the time. That's 100 kilometers per day, five days a week (50 kilometers to work and another 50 kilometers back).


EDIT: UNTIL THIS DATE, I HAVE NOT OBSERVED ANY WATER CONSUMPTION, with the expansion tank between its minimum and maximum levels.

Hutfahrer wrote:

If it had regenerated, the oil emulsion would not have been ejected from the exhaust but would have burned off. Please definitely check the condition of the fluids in the oil and water circuits. Both should contain only oil or only coolant, respectively. The statement regarding short-distance operation or, generally, the usage profile is still important.

He was 99% regenerated because I drove from a location approximately 6777 meters away, where he had been parked and not running, all the way to my garage. And normally, the oil should be black when it's circulated.
My girlfriend drove her car to work today as usual. I need to check the exhaust again tonight to see if it's leaking anything. If it is, it will probably take some time for everything to clear up.

I'm also going to try tapping the frozen bleed valve, even though I've never experienced that with a diesel engine before.
The oil-water sludge is still a concern for me.

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If it had regenerated, then the oil emulsion would not have been ejected from the exhaust but would have burned off.

I think it's condensed oil vapor that was already in the exhaust before the regeneration process. The light color indicates an intact DPF .

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Nowadays, a bunch of labyrinths and valves are built into the valve cover to handle oil separation. Possibly, they are frozen or broken, causing the MÖL to be ejected in large quantities. As a test, direct the venting to a separate container.

. Regarding the engine ventilation system, including the valve cover, I would also start there.
The emulsion is naturally exacerbated by the extremely high humidity of recent weeks.

Yesterday, after driving twice for 50 km each time, the same thing happened again.

Okay, I've now directed the venting process into a plastic bottle and briefly short-circuited the EGR cooler hoses. The coolant level hasn't changed, but this is just for testing purposes.

Yesterday, I checked four vehicles with the "CR" designation, two of which were driven primarily for very short distances, but I couldn't detect any oil/water emulsion in any of them.

Also, also check the intake area and air filter to see if it's somehow sucking in stagnant water or water that has accumulated during rain. It's very strange for a vehicle designed for long distances.

Best regards.
Christian.

Today, I checked again after driving 4 times 50 km and 2 times 30 km (no highway, but country roads and through towns). The intake hose in front of the turbo is now free from any emulsion. However, there's a significant amount of condensation water in the plastic bottle where I redirected the ventilation hose.

Yesterday, I drove in temperatures of -1°C, and after about 8-10 km, the coolant temperature reached 85°C, and then, after another 3-5 km, the oil temperature also reached 85°C.

Over the next 20 kilometers, the water and oil temperatures fluctuated between 82°C and 87°C.

I deactivated the EGR system and locked it mechanically today.

Why is it producing so much condensation? Other engines probably aren't experiencing higher oil temperatures in these outside temperatures either.

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I deactivated the EGR system and locked it mechanically today.

Unfortunately, this will cause the engine to take even longer to warm up.

Yes, that's true, but it should have a higher combustion temperature, and therefore potentially get hotter overall.
After being turned off, it also didn't take much longer to reach the same temperature again.

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Why is it producing so much condensation, while other engines probably don't experience a higher oil temperature in these outside temperatures?

If it's not actually consuming coolant, the condensate is likely accumulating inside the engine in areas where the dew point is regularly exceeded, and it will now need to be evaporated.

Then there would have to be quite a lot of "water pockets" forming. Because the internal engine volume isn't large enough for even fully saturated air to condense significant amounts of water.

"Someone even put windshield washer fluid into the oil filler cap before, which is something that's apparently happened before..."

Okay, anything is possible, but I was more thinking about an oil/water emulsion. And that kind of thing accumulates and forms everywhere where it's cold enough. Who knows how much of it might still be in the engine...

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Yes, that's true, but it should have a higher combustion temperature, and therefore perhaps ultimately become warmer.

Unfortunately, that's nonsense and definitely doesn't appear anywhere here. The maximum combustion temperature, i.e., the peak value, increases.
The maximum temperature reached during combustion does not tell us anything about the total amount of heat generated by the burning process.

The logic dictates that if you burn the same amount of fuel with a colder mixture of air instead of partially hot exhaust gases being recirculated, then less heat is generated overall.