Help! Weirdest oil leak I have ever seen.

Little Dog

Little Dog

A2OC Donor
European-Union
I've had an oil leak on the RH side of my engine for many years. The oil drips onto the RH inboard drive shaft joint and gets thrown all over the engine and gearbox.

I've refit the cam cover, refit the tandem pump, resealed the sump, torqued the drain plug, checked the rear crank seal. On advice from sco and RAB I've checked the turbo oil feed and return pipes. It all appears fine.

This morning I cleaned the back of the engine, started the car and went under there and watched. To my amazement a blob of oil appeared to grow out of the No3 cylinder exhaust manifold retaining nut:

YwUeUVR.jpg


I couldn't see oil flowing from above so I blew the whole area clean with compressed air. Within minutes the blob had reformed and appeared first around the gap between the hex of the nut and the shake free ring on top!

Any ideas?
 
I guess ..... somebody drilled a 6.8mm hole into the engine head and made M8 threads there, that might have punctured one of the oil distribution channels... and now the oil is pushed/feeded by 4 Bar oil pressure along the stud bolt, out through manifold stud bolt hole and since the surface between the corroded nut and the washer is not the best.... this will be the easiest leak path :)
(the thread it selves never seal up due to that when you torque up you make the back-side gap bigger and bigger while increasing the torque... and thats the path your oil is using in your case probably )

BTW: I really like those who never give up to identify a leak :)
 
Sounds like you want to remove the stud and re-fit with a thread sealant - something like Loctite 577. You could increase the chances of success by adding a low thermal conductivity washer under the nut.

Simon.
 
Thank you dieselfan; that oil leak has been driving me nuts for years. Determined to get it this time as I thought I had covered all the options.

It's an owned from new car and that side of the engine has never been worked on. Unless that is there was an Audi instructed mod that was done when the car was in for warranty work.

Going to clean up with brake cleaner and run the test again.
 
sco said:
Sounds like you want to remove the stud and re-fit with a thread sealant - something like Loctite 577. You could increase the chances of success by adding a low thermal conductivity washer under the nut.

Simon.
Click to expand...

There is a sealing washer under the nut. I'm going back under the car now. If I get the same result I will order a stud, nut and washer.
 
Sealing washer under the nut won't work as it's tracking up the thread. The low conductivity washer is not for sealing - it's to stop the heat from the exhaust manifold from killing the thread sealant.
 
I fully agree with Simon that to fix a new stud into the engine head with Loctite will be the best solution in your case.
Though, please be very careful and do not apply to much "Loctite" (or an other brand) to the threads. Why be careful? Because Loctite seals very effective and since the hole is approx 22mm long you actually risk to distribute Loctite into the engine oil or expand/crush up the threaded hole by the hydraulic force you create while threading the stud into the hole with lot of Loktite on it.

When I wrote "somebody drilled a hole" I meant "Heinz at the plant at day 0" and not you now :) (My English should have been better, and I try to improve, but it is so fun and educational to be in here that I cannot stop... so please bear with me and the lack of correct terminology and the misunderstandings I create, and please correct me :) :) )
 
I think I've found it and its not that stud. I cleaned up and ran it, oil appeared at the stud but not as much as previously. There also appeared to be a growing stain of oil on the cylinder head to the left of the exhaust manifold. my attentions switched to a blanking screw above a bracket to the left and above the suspect stud:

a3fqETg.jpg


Cleaned up again and ran for about 30 minutes, nothing. Switched off and let it cool down:

XFfGAgi.jpg


If that plug is related to oil way drilling then I think I have my culprit. If not then its back to the cam cover? Is there anything else up there?
 
Thanks Spike that is a very useful overview of my engine. I'll probably read it cover to cover.

I think the routing of the oil ways suggest I could have a cross drilling but it's not detailed enough to be conclusive. I'll have to try and tighten it up and see what happens.

Phil
 
Just this problem to solve and I have my A2 back.

A couple of days ago it was dripping oil on the drive so I had a good check up the the back of the engine and it was wet in all the same places as above. Had a good clean up and noticed oil around the vac pipe connection to the tandem pump. Cleaned it, removed it and put it back tighter. Spent a good hour under there with the engine idling and apart from the mystery oil leaking nut above I couldn't see oil any where. Blew the nut off and that stopped producing oil too. I final clean down and checked the following morning; still clean and dry.

Yesterday had the A2 on towing duty, clocked up 60 mile +, once home checked and yes there was some oil but not much. It was raining so back under the car this morning. There was oil on the bottom of the engine block at the joint with the clutch housing and below on the sump to clutch housing joint:

Pyim6H4.jpg


Also above on the turbo oil feed pipe:

xhKFRMN.jpg


Looks like a problem around the tandem pump to cylinder head joint or something up there. Checked the cam cover joint and tandem pump and was able to conclude nothing, no obvious wet patches. My Mrs went to have a look and concluded the leak was the blanking plug in the back of the cylinder head, see above. I cant budge it either way; so to exclude it:

4JZVlAC.jpg


Is there anything else before I strip out the cooling system to get a better look at that tandem pump?
 
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I'd take leaking oil at the moment - mines ingested a glow plug tip. Hoping to borrow a boroscope from work to see what the damage is.

Simon.
 
sco said:
I'd take leaking oil at the moment - mines ingested a glow plug tip. Hoping to borrow a boroscope from work to see what the damage is.

Simon.
Click to expand...

Fingers crossed for the wrong plug voltage and it, or they, never heated with the piston at TDC. I think if that happens there is the potential to melt the piston crown.

Investigating my leak again this morning and your right, I wouldn't swap it for an engine rebuild. Best of luck.
 
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Arrrrghhh! cant find it. It's up the back of the engine somewhere.

I get this much oil overnight:

wW4CmLm.jpg


The sealed blanking screw does have some oil around it but I cant detect a breach of the sillicone. It would only take a pin prick though:

O8XsZ0X.jpg


Does anybody have a head off a TDi and be able to tell me what that blanking plug does so that I can exclude it??? Please, please, please.

There was something on a heater hose but that was clear and did not smell of engine oil:

O8XsZ0X.jpg


Same picture as above.

So I'm no further forwards. I have to run it again and see if there are any clues. For me it can only be the mystery plug (please somebody excluded), the engine cover gasket or the tandem pump?

Frustrated

Phil
 
I had an oil leak with my Porsche and that is exactly what the local dealer did with a camera linked to Germany. I kicked off a massive stink and was appeased with a 911 for a week ?. Appetently it was idling for hours before they notice the seal that fails had again failed. Well I wish I could afford the same technology but I can’t and neither is the accessibility as good, they dropped the gearbox off.
So what really want is for somebody to tell me what that plug is and then I can order a new engine cover gasket and screws. If that doesn’t work the tandem pump is coming off. I’m not joking I’ve been on my back watching for leaks under my car for over three hours now and seen nothing conclusive.
Where is that great big branch?
 
Sorry SCO my frustration is not directed at you. It is at the car and difficulty to diagnose. There is absolutely no access.
I will never ever buy another Audi based on this experience but I will not give up on this A2.
 
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