Oil leak from crankcase ventilation/oil seperator A3 PFL 2.0 TDI CUNA

[hydo1]

My A3 has recently started drinking oil, it used to use 500ml to 1,000ml every 10,000 miles whereas more recently I am having to top up (with around 500 ml) every few thousand miles.

I noticed that there was oil building up all the way around the oil separator on the top of the engine and have pulled off the crankcase breather hose that runs to the turbo inlet to inspect. In this there was a large amount of oil/water emulsion building up within that hose. I have cleaned this out and it returned to the same amount after about 100 miles. The car is not loosing coolant, so this water must be condensation. which I suppose is expected at this time of year

Has anyone got any suggestions as to how to further diagnose this oil consumption further as removal of the oil separator looks pretty involved.

For context I currently am doing ~500 miles a week (50 mile commute each way to work) which is mixed motorway and country roads and the car is on 98k miles

 

[BrummieLad]

My A3 has recently started drinking oil, it used to use 500ml to 1,000ml every 10,000 miles whereas more recently I am having to top up (with around 500 ml) every few thousand miles.

I noticed that there was oil building up all the way around the oil separator on the top of the engine and have pulled off the crankcase breather hose that runs to the turbo inlet to inspect. In this there was a large amount of oil/water emulsion building up within that hose. I have cleaned this out and it returned to the same amount after about 100 miles. The car is not loosing coolant, so this water must be condensation. which I suppose is expected at this time of year

Has anyone got any suggestions as to how to further diagnose this oil consumption further as removal of the oil separator looks pretty involved.

For context I currently am doing ~500 miles a week (50 mile commute each way to work) which is mixed motorway and country roads and the car is on 98k miles
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First thing to do is to check for any leaks around the world bivouac places like the oil sump plug and filter housing. It’s not uncommon for people to overtighten the filter housing after an oil change, thereby cross threading it and reducing it’s effectiveness. There are numberous other place it could leak , such as rocker cover gasket failure, turbo burning oil, engine burning oil so it’s difficult to say where exactly your issue is (assuming it is an issue and not normal consumption). Finally it could be the engine itself burning the oil due to piston wear, which can only be fixed by an engine rebuild unfortunately.

You don’t say the exact mileage after which you top up, but if you’ve got the 184 variant it seems to burn a litre every 5-7000. People with the Golf GTD and Skoda VRS report similar consumption.

 

[hydo1]

First thing to do is to check for any leaks around the world bivouac places like the oil sump plug and filter housing. It’s not uncommon for people to overtighten the filter housing after an oil change, thereby cross threading it and reducing it’s effectiveness. There are numberous other place it could leak , such as rocker cover gasket failure, turbo burning oil, engine burning oil so it’s difficult to say where exactly your issue is (assuming it is an issue and not normal consumption). Finally it could be the engine itself burning the oil due to piston wear, which can only be fixed by an engine rebuild unfortunately.

Thank you Sir, I have checked the oil filter housing, oil sump plug and had an inspection of the rest of the engine for any external leaks. There is a reasonable amount of oil on the top of the engine (and a little pooling in the injector wells for cyl 3 and 4) so that seems like leakage from around the top. I am pretty sure that it is oil based on smell but appreciate that it may be diesel leaking from one of the lines to the fuel injector. However, there is no oily stuff on the piece of polystyrene foam covering the injectors and where all the connectors are so I think it's unlikely that it would be fuel.

You don’t say the exact mileage after which you top up, but if you’ve got the 184 variant it seems to burn a litre every 5-7000. People with the Golf GTD and Skoda VRS report similar consumption.

Okay, my consumption is inline with this as mine is the 184 engine however the reason I ask is that this has gone up quite a lot from the previous 50k miles I've done in the car where it hasn't needed more than 500ml between the 9k mile service interval (been using Castrol Edge LLIII 3W-30 at each change).

 

[BrummieLad]

Thank you Sir, I have checked the oil filter housing, oil sump plug and had an inspection of the rest of the engine for any external leaks. There is a reasonable amount of oil on the top of the engine (and a little pooling in the injector wells for cyl 3 and 4) so that seems like leakage from around the top. I am pretty sure that it is oil based on smell but appreciate that it may be diesel leaking from one of the lines to the fuel injector. However, there is no oily stuff on the piece of polystyrene foam covering the injectors and where all the connectors are so I think it's unlikely that it would be fuel.

View attachment 196379


Okay, my consumption is inline with this as mine is the 184 engine however the reason I ask is that this has gone up quite a lot from the previous 50k miles I've done in the car where it hasn't needed more than 500ml between the 9k mile service interval (been using Castrol Edge LLIII 3W-30 at each change).

That could potentially be diesel or oil. It could just be spillage from when the engine was last topped up, and you’re seeing the left over residue left behind. Best thing is to degrease the engine and have it washed, and then see if any fluid reappears, and take it from there. Your consumption seems in line with a lot of others with this engine, so it could just be normal use.

 

[Pjn90]

Hiya hydo1

did you ever find the reason for the random rise in oil consumption?