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Discussion Starter · #1 ·
Hello all,

Apologies if this has been covered elsewhere but I couldn't find a search option for forum threads.

Mk4 Golf 2002 1.9 tdi ATD 192,000 miles. Runs really well except that it is pushing oil up through the filler cap. My mechanic has checked the breather tube for the pcv that's built into the rocker cover and saw no blockages.

The N75 has died so have ordered a new one and some fancy silicone hoses but am not sure that it is responsible.

The only other possible symptom is the turbo waste gate is very quiet (virtually silent) but the turbo still pulls well.

Other than this issue the car runs like new and recently returned 800 miles for one tank of 90% motorway/highway driving.

Any suggestions would be greatly appreciated.
 

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Your car spec says 2002 Bora 1.9 TDI is this 2002 Golf 1.9 TDI ATD yours or are you trying to fix someone else's?

Any problems search TDI Wiki as that covers write ups and forum posts.

I have 5 error codes for Positive Crankcase Ventilation (PCV).

You need to get your motor scanned (preferably with VAG-COM\VCDS) for any error codes logged in the ecu and post them, that will save a lot of guessing and check systems out.
 

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Discussion Starter · #4 ·
Hi Keith,

Thanks for your reply.

The Golf is mine
I bought it in October last year.

The Bora/Jetta sadly, is no longer with us. In between losing the Jetta and gaining the Golf I've also had a B6 Passat estate for five years

The only error code showing is 17664 which refers to the coolant temperature sensor circuit.

There can't be much wrong with her as she starts and runs like a new car. If anyone has any suggestions they would be appreciated.

Thanks.
 

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Well you need to remove the Bora from your car spec and add the Golf so we know which car your talking about.
 

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Discussion Starter · #7 ·
Thanks to drucifer for the heads up about the oil filler cap gasket.

There are no error codes stored related to the pcv so have thought it may be an early stage mechanical issue that hasn't set a check engine light or code as yet?

The oil being pushed through is about half a litre after 5000 miles driven and although not excessive it does thoroughly soak the back of the engine.

Have established the pcv vent on the rocker cover is breathing free and is clear of obstructions as is the other end of the tube that joins the accordion cold air intake.

There is a lot of oily gunk built up around the egr so am going to clean and rebuild it with new gaskets. Have also ordered two oil filler caps seals (thanks to drucifer) as well.

Will keep everyone posted on the progress.
 

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Are you sure it's coming from the oil cap and not the valve cover? Quite common for the valve cover to leak at the rear and run all down the back of the engine. Just whip it off, clean up, use appropriate sealant and refit.

Maybe the oil cap just seeps a little because the seal is roasted and squashed from years of service.
 

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Discussion Starter · #9 ·
Hi Seatman,

Thanks for your post. My mechanic says he thinks it is coming from the filler cap and it is pooling inside the rubber ring below the filler hole.

So far I've removed and cleaned the egr/intake manifold, replaced the vacuum hoses except for the turbo and put two new gaskets inside the oil filler cap.

Have also bought the valve cover gasket but haven't swapped it over as yet.

I went to check my oil level and the dipstick tube came away with it so am presuming there was a hairline crack in the orange plastic tube that may be responsible for pressurising the crankcase?

Will change the valve cover gasket when the new dipstick tube arrives and keep everyone posted.
 
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Yea, those dipstick tubes rot. But that's not causing your issue. Did the new filler cap gasket help?
 

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Discussion Starter · #11 ·
Hi udraft,

Thanks for letting me know.

I've only done about 250 miles or so since the oil filler cap gasket replacement before the dipstick tube snapped so it's too soon to say.

It certainly looks dryer around the cap but will need to do more miles before I can make an unbiased conclusion.
 

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Discussion Starter · #12 ·
After changing the valve cover gasket and putting two new filler cap gaskets in place and cleaning the rubber cup under it there is still Mobil 1 oozing out!

The valve cover gasket replacement seems oil tight but oil is still coming out around the plastic filler neck and going down the back of the valve cover.

The rubber cup under the filler cap is bone dry so it's not coming out of the cap so it must have a crack somewhere on the filler neck of the plastic valve cover.

Have taken a picture and will attach it if it's not too large.

Have just ordered a used one online for £20 so hopefully that will solve the problem.

Will keep you posted.
 

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Discussion Starter · #15 ·
I fitted two new ones after reading somewhere that it solved the problem for someone else.

As it's not leaking from the filler cap anymore I don't see how your suggestion will improve things as the existing leak appears to be in the plastic filler neck itself wbere it joins with the rocker cover and the pcv is breathing as it should.

Will take your advice because thats why I started this thread, but don't see how it will solve the leak lower down?

Will trial your suggestion for a few days until the replacement rocker cover arrives.

Will keep everyone posted.
 

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Discussion Starter · #17 ·
The leak appears solved.

The raised filler neck (pictured above) had loosened anti-clockwise from the valve cover and engine oil was coming through there.

Have tightened it clockwise until the retaining extension is as far clockwise as it can go.

That with the new valve cover gasket have solved the leaks.

Thanks very much to everyone who offered their advice.
 

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The leak appears solved.

The raised filler neck (pictured above) had loosened anti-clockwise from the valve cover and engine oil was coming through there.

Have tightened it clockwise until the retaining extension is as far clockwise as it can go.

That with the new valve cover gasket have solved the leaks.

Thanks very much to everyone who offered their advice.
Hi,
I am having this issue. Please can you tell me the parts you ordered to fix it as I have no idea what it is called and cannot find it anywhere. Thanks
 

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The poster from 2019 actually didn't fix it with too many parts. He turned the neck clockwise which had come loose. He may not have needed the seal then.

The filler neck seal is easy to locate on a browser search. Add your vehicle year, make, and model to this in browser search / "Oil filler neck seal for 2010 ................."

Good luck
 
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