Oil separator leaking ?

[Le_Combattant]

Hello

As always, I'm still trouble shooting my engine hesistation issue because now, even with decent temps, engine has some issue to produce nice and smooth power between 1000 and 2000 (maybe a little bit more) rpm.

Still, I have to investigate around the LPFP side, because the pressure delivered by the pump was quite low.
According to my lambda settings, and LTFT, ECU is always looking for a more lean condition (-0.8% LTFT) and some times in idle (hot engine) around -2/3 and sometimes -5%.

I was today on Briskoda Forum and I found this topic:
https://www.briskoda.net/forums/topic/5 ... placement/

So according to the owner, lean condition + fault code triggered.
He found the oil separator leaking, replace it and now all good.

According to internet, Drive-ru mainly, this oil separator is well know to leak and creat like air leak inside the engine block.

So I decided to check mine and found this:

Capture d’écran 2025-09-10 172213.jpg (142.38 KiB) Viewed 790 times

From the small area I could see through the bonnet, it looks quite ‘thick’ visually.
To give you an idea, the plastic semi-circle to the left of the socket corresponds to this:

1.jpg (90.02 KiB) Viewed 790 times

So somewhere I have a leak. Nevertheless, I did the test by removing the oil cap from my block (engine warm, idling), and I have a ‘moderate’ suction effect (difficult to judge). In any case, when unscrewed, it does not fall out and remains sucked in by the vacuum.

Tomorrow I will see If I could go under the engine bay and getting a better view.

What do ou think ?

[2226]

Mine's been leaking since I got the car with about 20,000km on it.
Bought a replacement and then bought several forms of sealant until I found "the right one".
Have I done the job yet? No. To get proper access to it in order to torque up the bolts means inlet manifold off.
Only removing manifold when I need to make template for the intake port so I can 3D print adapter for carbon clean it needs.

I haven't check on lean condition or anything like that. No fault code. The front of the engine is always wet with oil running even down to the filter. So it's leaking, but I don't think it's sucking in air to cause any faults.

[Le_Combattant]

Mine's been leaking since I got the car with about 20,000km on it.
Bought a replacement and then bought several forms of sealant until I found "the right one".
Have I done the job yet? No. To get proper access to it in order to torque up the bolts means inlet manifold off.
Only removing manifold when I need to make template for the intake port so I can 3D print adapter for carbon clean it needs.

I haven't check on lean condition or anything like that. No fault code. The front of the engine is always wet with oil running even down to the filter. So it's leaking, but I don't think it's sucking in air to cause any faults.

So this part is quite weak, or sealant is too thin. 20000 km is very very low mileage.
The official sealant is the D176501A1, with fast cure time (30min later, you can add oil and run engine).

You don't have access from the bottom of the engine ?

But yeah, mine is leaky as well:

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PXL_20250911_084944579.jpg (2.23 MiB) Viewed 741 times

[2226]

Sure you can access from the bottom, but I found it very awkward to do. The bolts need to be torque to some weird low value and in a sequence. I don't have access to get to the top ones. Part is plastic and guaranteed wrong torque will warp it and it'll leak again.

Permatex #51813 is anaerobic sealant that can be used and equivalent of the VW item.
There is also a prep spray for this sealant, but proper clean of surface will do the trick.
Other sealants recommended to me had other chemicals that would not be so great with aluminium.

[2226]

That leak also looks minor. It's misting out of there. Looks more like road dirt. I have oil running past the filter.

As for it happening at low mileage... modern VW. Is what it is.

[Le_Combattant]

That leak also looks minor. It's misting out of there. Looks more like road dirt. I have oil running past the filter.

As for it happening at low mileage... modern VW. Is what it is.

For sure it's oil
I get my hand and grab the dirt, it's very oily.

[Le_Combattant]

Sure you can access from the bottom, but I found it very awkward to do. The bolts need to be torque to some weird low value and in a sequence. I don't have access to get to the top ones. Part is plastic and guaranteed wrong torque will warp it and it'll leak again.

Permatex #51813 is anaerobic sealant that can be used and equivalent of the VW item.
There is also a prep spray for this sealant, but proper clean of surface will do the trick.
Other sealants recommended to me had other chemicals that would not be so great with aluminium.

Torque in cross patern, 9Nm.
Permatex seems to be a good brand but nor available in France so I have to bough VW's home sealant.

[2226]

Would be curious to see if this resolves your issues.
I see the 1.5TSI has similar separator, but with an electronic valve on it. Wonder what issue that was trying to solve.

[Le_Combattant]

Would be curious to see if this resolves your issues.
I see the 1.5TSI has similar separator, but with an electronic valve on it. Wonder what issue that was trying to solve.

Yeah I saw that few days ago. Maybe they found that the check valves on tubro and inlet manifold were not that great.

But now, I have to deal with my damaged oil pan and a nice leaks (because of the damaged threads):

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PXL_20250911_085403368.jpg (2.67 MiB) Viewed 687 times

[2226]

Fun times.

Look at that ... your oil sensor is connected! I still haven't figured out why 2014+ 1.2TSI down here have those sensors but not connected. VW forcing engine rebuilds.

[Le_Combattant]

Fun times.

Look at that ... your oil sensor is connected! I still haven't figured out why 2014+ 1.2TSI down here have those sensors but not connected. VW forcing engine rebuilds.

So, you have the sensor but not the wiring ?

[2226]

Yes.
Confirmed on a few other 6C as well. Sensor fitted, no wiring.
At one point I thought the plug might just have been ripped off my something on the road, but in fact there is no wiring to it.

I have no idea why VW did this. Probably cutting costs. Engines were complete, but cut the wiring.
Maybe too many people complaining too often about low oil level.

[Le_Combattant]

Yes.
Confirmed on a few other 6C as well. Sensor fitted, no wiring.
At one point I thought the plug might just have been ripped off my something on the road, but in fact there is no wiring to it.

I have no idea why VW did this. Probably cutting costs. Engines were complete, but cut the wiring.
Maybe too many people complaining too often about low oil level.

So like aircraft manufacturer like Aibus or Boeing, they like (for no reason) to make change between to same plane...I love this world

[2226]

Feed the shareholder.