Chasing an oil leak

A6 All/ S6 All
#1

Hi everyone,

Have just purchased an S6 V10 06 and am chasing a dreaded oil leak so far I have replaced the following.

-Valve/rocker covers and gaskets
-Oil Filter housing (Both o’rings)

Oil seems to still be dripping from the front of the motor how ever for the life of me I cannot find where from.
Mechanic has suggested possibly faulty PCV/oil separator due to high suction when oil cap removed how ever after Upto $6000 so far and I’m not going to risk replacing anymore items Willy nilly. To be fair I have had quiet a few things replaced not related how ever this leak is going to be the death of me. Struggling for where to look next.

#2

Definitely get everyone’s input here. I could have saved thousands at the beginning if I would have checked in here first. Lots of knowledge. Things are much more manageable now.

#3

if the oil leak isn’t going to result in damage of any kind, my suggestion is to switch to an oil with fluorescent dye in it and then bust out a blacklight. easy way to identify leak areas.

wouldn’t be surprised if there were dye additives for oils though (that way you don’t have to go through a $100 oil change).

that’s about all i got offhand.

#4

Do you have any pictures. It can help give us a better idea on what your dealing with. There are a lot of areas where this can be coming from.

#5

Hi Justin,

See attached it’s still leaking from the passengers side (NZ) somewhere. The highest point I’ve found oil so far is middle of the engine how ever after checking the 2 holes / Gallerys it was not leaking from there. How ever have removed intake manifold again and something is still leaking towards the back as have found oil pooled inside. This is why I was thinking it was possibly a faulty PCV valve. When the car is idiling it doesn’t leak at all ( have removed undertray) how ever if you take it for a hard drive it seems to be comming out of multiple areas.

#6

http://i68.tinypic.com/34777fp.jpg

http://i65.tinypic.com/33jl6x2.jpg

#7

http://i68.tinypic.com/2q19dnk.jpg

#8

Very odd indeed.

That’s over the thermostat correct?

I’m thinking lower valve cover gasket, but can’t think where else that oil would be coming from.

#9

I had a similar issue not too long ago, took me weeks to figure out where it was coming from. I had replaced the oil pan gasket, then the vc gasket but was still getting oil seeping onto front passenger side of motor. It was the o rings for the oil cooler lines.

#10

Yeah definatly an interesting one seems like I’m dealing with 2 leaks.

  1. inside the Valley
  2. somewhere mid level at the front of the motor
#11

Sorry just thought I would mention it’s all over the radiator fans as well whether or not there is lines near that or it is sucking it up under high speeds and throwing it everywhere ?

#12

there’s the power steering cooler in front of the radiator… but maybe it’s oil being slung off the crank. Just all really odd.

#13

That can be from the oil running down the front of the motor and then hitting the crank pulley and getting spit all over the place then getting in contact with the fan blades. You took some really great pictures. The oil on the top side of the one bolt suggests that its not coming up the pan to the bolt. It would suggest its coming down to the bolt.

As for the PCV you do have a PCV drain line that comes off of the Oil separator. check that. That could be the sorce of the oil spil. I know I have seen several times that line gets brittle and cracks. Then oil starts to weep out.

#14
#15

Right so.

New PCV Valve, and have replaced oil drain line bloody thing is still leaking. What else possibly could this be. Is there anything else on the front of the motor that seals.

Have done Front Main Seal already.

#16

Update #2

Went and bought myself a snake camera to see whats going on. Further to this it is coming out of the Oil Galleries still!! apart from the Oil filter housing O’rings ( O’Ring and Figure 8) what else could be a possible cause as I have had these both replaced in the last month.

#17

Any luck yet? My recently bought 2007 S6 Avant is having excatly same issue. Major oil leak from under the intake.
So far: Intake replaced, oil filter housing’s filters replaced and carbon clean done.
Thought those filters would sort it, but after everything was back together, leak was still there.
But as I bought it from shop, all work is done under warranty but its been over 5 weeks now >:(

Luckily they gave me 2006 Skoda Octavia 1.6 as loaner…

https://workshop-manuals.com/audi/s6_quattro_sedan/v10-5.2l_(bxa)/engine_cooling_and_exhaust/engine/engine_lubrication/engine_oil_check_valve/component_information/locations/ Have you investigated this part? Not really that many places oil to come out under the intake

I also bought snakey cam prior taking car to get fixed to chase leak but cam came few weeks ago and dont have access to car atm

#18

Just to reply as this thread is now fixed:
My issue was oil cooler lines/gasket/o-rings. Got them replaced and it sorted last oil leak.

Now after few months it developed new problem. CEL at WOT. Blinking, somewhat rough idle.
Changed plugs. Old plugs looked good.

But I believe my issue is with PCV. I have that noise coming from behind the engine and as I removed PCV, it was very oily so I believe it drew oil from pan because vacuum. rubberthingie (membrane?) was intact.

Oil leaks found after purchase:

  1. Oil filter housing
  2. Oil cooler lines
  3. Somewhat put random plug and gasket to oil pan. Replaced with OEM and for now, my S6 is oil leak free :slight_smile:
#19

The blinking CEL is NO GOOD> That’s a stop WOT condition. Rough idle and missifres on WOT pull can be a range of things but the ones to look for are

Check your injectors. They NEED… NEED to be cleaned serviced or replaced. They have a incredibly high failure rate. Also check the dates on your coil packs. Plugs are good to change but coil packs generally go bad and are the other major cause of misfires.

This isn’t to say you shouldn’t look at clean or replace your PCV and oil separator. They go bad over time. I just say check the big items as well.

#20

Thank you for the good information.

In past 6 months I’ve read quite a lot about this car and its “quirks and features”.
Injectors and coil packs are top of my to-do-list.

Took PCV out, cleaned it and checked membrane, it was ok so I just put it back in.

Found vacuum leak where left tbody meets airdividerbox. Surface on that divider was very uneven and also had one crossthreaded hole. Good times.

Changed my fuel filter today and found out that I had original one from 2007 with over 100k miles.
Somewhat dirty fuel came out :slight_smile:
That seemed to help my CEL @ high load quite a bit so I really need to check my fuel pump aswell.

Is there a way to check low and high fuel pressures with VCDS and if so, where and what are ok values? Tried searching forums/online and no luck with S6.
Codes I’ve got are multiple misfires and multiple misfire possible cause low fuel pressure.
No exact cylinders, only “multiple”. Ofc it can be injectors or coils but should those give exact cylinder misfires?

And also had my battery checked. It was good but very low voltage so I bought battery tender and hooked it up.