MK7 2.0 TDI GT (184), Oil leak from top of engine

[Andy Grob]

I'm helping out with my daughters 2.0 tdi GT 184 (around 65k on clock). She has owned the car about 18 months and put around 10k of these miles on herself, and is a very careful driver (99% of driving is done below 3500/4000 rpm!). Hence not a recent purchase, just a recent issue noted after 10k easy miles without any issues

About 2 months ago she has a persistent an notable oil leak, which seems to be coming from the top of the engine. Thought is that it was losing perhaps 0.5 to 1ltr per week, with light usage. No issues with exhaust gases, neither blue nor white...just normal. But there is a repeat welling of oil around the glow plug recess, and then a downward migration of oil eventually to ground and fresh markings on driveways after parking.

It was originally thought that the oil was leaking from above and possibly coming from the rocker cover gasket, so this was swapped out for the first time perhaps 4 weeks ago. After the 20 to 25 mile drive home, the problem remained.

A second garage has done the rocker cover work again, all with genuine VW parts and the problem remains. Now about 100 miles since the second work and the problem remains.

Yesterday, I got it on my ramps, took of the skid tray underneath and cleaned as much of the engine and subframe as I could. Whilst under the bonnet, I cleaned up around the glow plug area and also found that the oil level was too high, so I syringed about 300 to 400ml. Bringing the level down to the 'top' of the dip-stick checker. After a 10 mile drive, the oil leak is very visible on around the glow plugs again and a simple 3 point turn in the street left oil drip marks again.


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Professionally I work on cars from the 1920's through to 1980's, and carried out a few simple tests to then better understand....how, why and where the cause may be. Whilst bringing the basic tests into a much more modern vehicle.

1) Oil filler cap off with engine running, there is a mild pulse of smoke/pressure coming out. Likewise at the dipstick tube.
2) The highest point of wet oil, is just around the glow plug recess and the cylinder head below the rocker cover.
3) No splash marks on the underside of the bonnet, hence it's not reaching the top of the engine by 'throw'. Instead it's being pressured 'to' and then leaking downwards.
4) The oil level may have been too high previously, but it is now correct.
5) Minimal, perhaps near zero leakage at idle. Hence, the leakage is only present with rpm and engine load.

If on an older car, my thoughts would be turning towards an issue with 'blow by' or crank case breathers and under load the engine is struggling to breath/vent properly. The result being that oil is being forced out from somewhere...perhaps the rocker cover gasket, filler cap or a pcv pipe of some type at the top end of the engine.


Does the problem sound familiar? Is there a PCV valve or breather which are known to fail, clog up, or other? Is this a common issue with a recognised 'typical' cause?


Any help or advice offered would be very much appreciated?

[Andy Grob]

Another clean up under the engine bay this morning and I can now see an area where fresh oil is leaking outwards. It may not be the only source however, it is at least a source.

The round silver shape to the forward right of the oil filler cap......any thoughts in regards to a possible cause? Severity? Ease of resolve?

Cheers,

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[Crasher]

Was the cover replaced or just the gasket?

[Andy Grob]

Was the cover replaced or just the gasket?

On both occasions, just the gasket replaced.

[Crasher]

Take the oil filler cap off with the engine running, see if you get a hiss as it comes away.

[Andy Grob]

Take the oil filler cap off with the engine running, see if you get a hiss as it comes away.

You mean whilst running, to see if it was holding pressure?

[Crasher]

I did one a week or so back from another garage who had given up, when I released the filler cap engine OFF, it went whooosh. New cam cover off the shelf at TPS, problem solved.

[Andy Grob]

I did one a week or so back from another garage who had given up, when I released the filler cap engine OFF, it went whooosh. New cam cover off the shelf at TPS, problem solved.

Very Interesting, thank you.

Did you find the actual cause, ie a crack...a blockage...a gasket tear etc? Out of interest, approx how much was the cam cover?

[Crasher]

The moulded in vent valve inside the cover, there are two new versions depending on engine code and the most common revised number is 03L 103 469 A and these are £223.09 plus injector bolts and strictly speaking you should do the injector seats, seals and hold down plates. If the hold down plates get swapped or turned around they can snap in service.