Help! Weirdest oil leak I have ever seen.

More interesting observations, the engine now stops very cleanly / instantly when turned off. Previously it rattled on a little bit.
Does the vac from the tandem pump also power the anti shudder valve? The only change I have made is to replace the pump.
 
Thank you, that makes sense. When I’ve finished running in a new pump I imagine the brakes wil be stronger too. Great result.
 
Little b****r is leaking oil again!
Same general area, RH side of the engine at the top somewhere. Will check out usual suspects, tandem pump, EGR, cam cover etc when the weather improves. Been dry for 2 1/2 years, not bad I suppose for an 18 year old daily.
 
Almost 4 years after I first spotted this weird oil leak:

albert 22.jpg



Feb 2021 oil leak turned out to be the tandem pump again. I fit a genuine gasket, it appears to have worked. So I assume this oil has come from the cylinder head cover gasket that I have recently replaced. A few observations, the revised Torx screws are not only a different drive the spacer is slightly shallower so they clamp the gasket slightly tighter. A found a genuine gasket in the attic, it is much softer than the Febi I removed. The genuine gasket was there because it was too soft to fit with the inlet manifold in place. I also had three original screws across the back because a hex head was easier to locate and torque with the manifold in place.

On this occasion the manifold was off so I had good access to fit the cover without the soft gasket falling out of the cover groove. Also had good access to torque up so have Torx screws all round.

Hopefully this time I have fixed it.
 
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5 years after starting to investigate the reason why the exhaust manifold studs can expel so much oil as the engine warms up I, quite by chance, amble upon the answer. This the exhaust manifold from the AMF I'm preparing:

IMG_0811.JPG


When I removed it there was a spill of oil from the studs under the EGR / tandem pump. The central stud hole is standard clearance but the outer two have significant clearance. Presumably for expansion? Whatever the reason there is significant capacity for oil storage. As it comes out as the engine warms up I would guess puddled oil gets in as it cools down?

However it gets there it is nothing to be concerned about.
 
Just read speed read this thread from the beginning as I have chased similar oil leaks on all my A2's. I have checked / replaced all the possible sources mentioned in this thread and I note the tandem pump would appear to have been the main source for philward, however I think I have something to add. I think the oil comes from the intake manifold via worn turbo seals. It can either leak out of the flattened orings between the egr, asv and spacer; or I strongly suspect from the inlet manifold to engine seal/gasket.

We know the intake gets oily. Having had small boost leaks in the past I can confirm that other than sound (and they don't always whistle) small boost leaks don't affect how the car drives, the turbo just works a bit harder. My theory is the oil in the air intake sits in the little ledge/slot inside the inlet manifold at the gasket. It doesn't tend to leak at tickover due to no boost. The oil just seals up the tiny gaps. When on full boost the oil is squeezed out of the gaps. Indeed the oil likely prevents any boost escaping as new oil is added from the intake (via turbo seals). The escaped oil then dribbles down the back of the block where it can't be seen due the the exhaust manifold being in the way and "magically" appears on low points of the exhaust manifold stud and sump/gearbox.

Unless the engine is out of the car, it is very difficult to clean up the engine where it mates with the inlet manifold gasket. It is also very difficult to correctly torque the inlet manifold bolts due to access. Both of these would help the inlet manifold leak enough to expel a bit of oil when under pressure, even with a new gasket.

Thoughts..
 
some Aerograde blue hylomar may help if it’s the tandem pump gasket . Or others in the area .
It works really well and seals most things better than silicone sealant.
 
My threads on this forum have helped me to compile a rough chorology of upper engine oil leaks and causes.

One of my earliest threads was 2010, car on 110K miles. I was commuting at the time and on the same commute the car went into limp mode for the first time. Audi diagnosed a failed injector and quoted £mega to fix it. I Googled the problem and discovered the injector harness can give the same symptoms. I decided to fit a harness and see if I had a fix. I didn't have a manual then so I binned the cam cover gasket and ordered a new one from Audi. If I had had a manual I would have known they are reusable.

Between 2003, Little Dog's year of manufacture, and 2010 Audi have changed the cam cover and gasket design and discontinued the original design. Old cam cover and new gaskets are not compatible. I did my best making use of gasket sealers. Also without a manual I didn’t know the tightening torque nor sequence for the cam cover screws. There was a shower of oil down the back of the engine. I tried multiple times to reseal / tighten the cover. At some point I gave up and fit a revised cover and seal.

Revised cover seal in original head cover. Oil leaks via the slots at each side of the bearing cap locations.

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in 2017 I had diesel leaking from my tandem pump, so I rebuilt it. The pump to head gasket did not have the essential blue silicone blobs on it. It leaked oil. More problems down the back of the engine. I fit a genuine gasket which eventually leaks oil so I fit a second Audi gasket, problem solved.

In 2018 I undertake major work on the engine and note the EGR valve is leaking oil. I buy a used one, it leaks oil. I buy and fit a new one.

By 2022 by now having replaced and tightened the cam cover so many times threads in the head strip and I have to coil them.

2023 all leaks fixed I discover bore scoring, bore pitting and general combustion chamber erosion. I have been supplied 5v glow plugs for my reg and they have melted in the engine.

Now I'm preparing a replacement engine.

@TAABVW this is a picture of the RH side (back) of my replacement engine:

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The inlet manifold has not been fitted correctly, RH most thread messed up. However it appears not to have leaked oil, the threads are dry. The LH port threads are soaked with oil but I believe it has come from above. Your suggestion is entirely feasible but I don't think I'm seeing it on my engines.

@BoeingPenny there are two types of tandem pump gasket, crush and rubber. If you get a non-genuine crush gasket then sealer like Hylomar is essential. It is not necessary with a genuine crush gasket. If you have the early rubber gaskets I would have thought, but have no experience, new ones should do the job.

Early tandem pump with rubber seals

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Audi tandem pump crush seal with blue sillicone applied

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Your photo demonstrates perfectly exactly what I was trying to describe above. Forgive me, but I don't understand your comment "However it appears not to have leaked oil, the threads are dry." Oil leaking out of the inlet manifold gasket does not have to wet threads....does it?

Looking at your excellent photo, it appears to me that the left two inlet (upper) ports have been leaking a little oil as evidence by the black wet grubbiness below those ports. Below the right inlet port looks relatively dry, as does above the ports. This is exactly the sort of thing I have seen when I've had engines out of my ATL A2's which has lead me to suggest this possible source of oil leaks down the back of the engine.

The little bit of oil showing in your photo in post #85 looks like it could have come from the same place and dribbled down behind the exhaust manifold.
 
TAABVW said:
Your photo demonstrates perfectly exactly what I was trying to describe above. Forgive me, but I don't understand your comment "However it appears not to have leaked oil, the threads are dry." Oil leaking out of the inlet manifold gasket does not have to wet threads....does it?

Looking at your excellent photo, it appears to me that the left two inlet (upper) ports have been leaking a little oil as evidence by the black wet grubbiness below those ports. Below the right inlet port looks relatively dry, as does above the ports. This is exactly the sort of thing I have seen when I've had engines out of my ATL A2's which has lead me to suggest this possible source of oil leaks down the back of the engine.

The little bit of oil showing in your photo in post #85 looks like it could have come from the same place and dribbled down behind the exhaust manifold.
Click to expand...
I was tempted to write that my picture could be taken as evidence of your suggestion being correct,

Everything will be sealed correctly when my engine goes back together. There should be no oil up the back of the engine from any source.
 
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