Oil-water emulsion in the charge air system

Hello everyone,

'I've owned a Golf IV TDI (50,000 km, PD 110kW) for a few weeks. Today, during a vehicle inspection, I noticed that some oil is leaking from the intercooler hose that connects to the left side of the intercooler. I removed the hose and discovered that there is oil inside the hose and in the intercooler, and the oil is gray in color. Upon closer inspection of the oil, I could also see water droplets.' It's normal for there to be a little oil in the hoses.
But the water content in it worries me!

What do the experts say about it?


Best regards,

Has anyone else had a similar experience?

Hello,

It's always helpful if you include your engine code (MKB) in your post. I'll just guess: a Golf IV with 110 kW as a pump-injector engine... MKB: ARL. Correct?

Okay! It's an ARL engine.

Exactly! It is an ARL engine.

Hello,
The compressed air, after passing through the ATL (presumably an air-to-liquid heat exchanger), is quite warm and therefore relatively dry!
How is it possible for water to accumulate in the LLK (likely referring to a specific device or system)?
Best regards,
Günther.

Günther wrote:

[Compressed air, according to the ATL, is quite warm and therefore relatively dry!] How is it possible for water to accumulate in the LLK?

It seems conceivable that some of the water content in the exhaust gases from the combined heat and power (CHP) plant is condensing within the large low-pressure (LP) steam turbine of the absorption refrigeration unit (ARU).

Otherwise, I can't think of any other "normal" water source.

Hello Ulf,
Then it would only occur in 'extreme' short-distance traffic.
I would thoroughly verschandeln the LLK and then observe it.
Best regards,
Günther.

Quote:

The compressed air, according to the ATL, is quite warm and therefore also relatively dry!

Yes, but relatively dry (relative humidity).

When it is cooled in the liquid-cooled condenser, it can no longer absorb as much moisture, which would then condense.

Where, for example, does the water inside the window panes come from with this kind of weather ?

However, it remains to be seen whether this will be sufficient to detect it in significant quantities in the LLK.

m;

Hello,
The air inside the LLK (low-temperature cooling) is always warmer than the surrounding air when it exits, and therefore 'relatively drier'; otherwise, the LLK would not function properly or would have an 'ideal' mixing rate.
Condensation is actually not possible in this case.
Best regards,
Günther.

@ Guenther

You're right about the temperatures.

However, it's possible that the turbo could also draw in humid air (e.g., in rainy weather), compress/heat/vaporize it, and then condensation could form on the low-temperature coolant system.

Theoretically, it's possible, but I don't know if that's actually the case or if it can really be so.

If the intake air is guaranteed to be non-condensing, then you are correct that nothing should deposit on the LLK (low-temperature coolant).

m;

Therefore, the only remaining possibility is a potential leak that could allow water to enter the vehicle during operation. However, this should manifest itself in other ways. Observe the LD (likely referring to a specific component or area) for any visible signs of leaks. I admit that it would be difficult for water to enter the passenger compartment while the vehicle is in motion due to a leak in the coolant system, but otherwise, I can't imagine how water could have gotten there.

@ Guenther

You're right about the temperatures.

However, it's possible that the turbo could also draw in humid air (e.g., in rainy weather), compress/heat/vaporize it, and then condensation could form on the low-temperature coolant system.

Theoretically, it's possible, but I don't know if that's actually the case or if it can really be so.

If the intake air is guaranteed to be non-condensing, then you are correct that nothing should deposit on the LLK (low-temperature coolant).

m;

Hello,
Behind the air filter, the pressure drops, and consequently, the temperature decreases. In theory, this is where the humidity should initially condense.
The ATL heats the air considerably, making it relatively very dry. While the LLK does cool down, the air inside is still noticeably warmer (and relatively drier) than the surrounding air. Theoretically, condensation could only occur in the LLK (likely referring to a specific compartment or area) if a very long journey was undertaken in heavy rain; however, this moisture should then dissipate during the 'next' journey in 'normal' weather conditions.
Is the water in the LLK mixed with oil to form a white emulsion?
Best regards,
Günther.

Therefore, only a possible leak remains, through which water could enter during operation. However, this should also manifest itself in other ways. Observe the LD, and any leaks should be externally visible. I admit that it would be difficult for water to enter the passenger compartment during driving due to a leak in the coolant system, but otherwise, I can't imagine how water could get there.

Hello,
There's positive pressure in the LLK system, so water can't flow in from the outside 'voluntarily.'
Best regards,
Günther.

You're right, Günther.

My considerations were very theoretical.

However, "your rearward pressure drop behind the air filter" is also very theoretical.

With a proper intake manifold, it's actually less than 20 mbar (I think I read that somewhere, those values keep popping up in my head).

m;

Hello,
Well, the air filter already creates a flow resistance, and therefore, due to the 'suction' of the air intake manifold (ATL), there is a slight 'vacuum' behind it.
But all of this is, in practice, 'insignificant' for the 'mysterious' water in the LLK.
Best regards,
Günther.

I know, that's why I said it's highly unlikely. However, since there's water present, he has to consider every possibility. Perhaps bypassing the intercooler might shed some light on the situation. I admit that the leak theory is far-fetched. Even if a tiny amount of water were to somehow get in when the engine is off, I think the leak would have to be so large that it would cause performance issues.