5.2L oil leak at the back of the engine

A6 All/ S6 All
#1

I’ve got signs of an oil leak at the back of the engine between the engine and gearbox. He guessed it’s coming from around the timing chain, but he couldn’t see anything because there is no room back there. It’s engine out to know for sure. I’ve got to decide if I’m gonna keep this car for another 3 years. Despite the low mileage, the maintenance has been piling on lately.

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Any suggestions on how to isolate this leak without taking the engine out? Are there any easy gaskets to replace that might also be a culprit? Has anyone had good luck using a $30 borescope from Amazon?

And if it is coming from the timing chain, apart from the gaskets, what parts are usually replaced?

#3

Does anyone hear timing chain rattle in this video?

#4

Not an expert, however I have used some of the cheaper bore scopes for some things and at least in my case it seemed to do the trick (cant say with any certainty that it will help you isolate your leak, however this seems like a pretty good thing to have around if you are into cars). In my case I can see the valve cover gasket is clearly leaking - I believe in terms of different kinds of leaks that is a comparatively easier gasket to replace and does not require removal of engine. You should be able to use a borescope to see by the sides of the valve covers to see if they are leaking. While replacing my air filters I noticed that you can get a much better look if you remove the air filters.

Good luck, keep posting.

This is what i bought, still working pretty decently

https://www.amazon.com/DEPSTECH-Waterproof-Inspection-Megapixels-Smartphone/dp/B01MYTHWK4/ref=sr_1_1_sspa?crid=13KD11DNI3PR5&keywords=depstech+endoscope&qid=1582428441&sprefix=deps%2Caps%2C199&sr=8-1-spons&psc=1&spLa=ZW5jcnlwdGVkUXVhbGlmaWVyPUEySVVCMlUyMDRNWlFIJmVuY3J5cHRlZElkPUEwNjQ4MDQzR0wxNVM5TlRGUFdQJmVuY3J5cHRlZEFkSWQ9QTA5NjM0ODU5SFUwVTFIWlRPRE0md2lkZ2V0TmFtZT1zcF9hdGYmYWN0aW9uPWNsaWNrUmVkaXJlY3QmZG9Ob3RMb2dDbGljaz10cnVl

#5

I ordered one of those, waiting for it to arrive. Then I’ll take a look down the firewall and see what I can find.

Ignoring the oil leak, the engine is running smooth and strong these days. But I still don’t know what timing chain rattle sounds like (see video above). I get a little rattle on startup, but it sound like things waiting for the oil pressure to get up to speed. After a min of driving it sounds like the engine is perfect.

#6

Are you certain the leak isn’t coming from your oil pan gasket?

#7

I got a scope!

Here are a couple shots

1 from around the right/driver side of the oil filter housing. I see fresh oil—and my last oil filter change was about 10mo ago.

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and 2 from the front of the block at the valley pan (pretty clean)

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I haven’t found any signs of oil from the cam gasket. Also haven’t gone under the car yet.

#8

I have a very slow oil leak, anytime I am driving the car hard it shows immediately, and it’ll show over a little while of easy driving. The oil is dripping from about the cats and it actually landing on the cat and smoking when it is on it. I’m guessing maybe a rear main is needing replaced?

#9

We know the oil filter housing leaks at the seals. Also keep in mind that there is the rear crank seal that might be in play. But from what you have shown here it looks like the oil filter housing

1 Like
#10

Since I’m still undecided on whether to keep the car or not, I’m taking things one step at a time.

  1. [done] reseal oil pan, new oil level sensor gasket.
    • just completed, but it looks like there is still an active leak. maybe from the front crank seal? I’ll wait for the crank seal to arrive in the mail, then take a look.
  2. replace front crank seal, timing belt (which is covered in oil). while the front end is off, peek under the IM to see if oil coming from the oil filter housing
  3. if oil filter housing, remove IM, replace gaskets and do a carbon clean.

from what I heard about timing chain rattle, it appears that I am clear. Hopefully nothing pops up that requires and engine out…

#11

The rattle was only on start up. It was the initinal tension on the chain and you could tell. You wouldn’t hear it constantly unless you had broken guides but at that point it wasn’t a rattle it was more of a slapping noise… So I would say your good there.

#12

Without physically looking at vehicle, I would be willing to bet front oil leak is from oil filter housing as well as check valve/spray nozzle cover plate. They are located side by side in rear of engine valley. Oil will leak from housing and cover, filling each indivdual gusset in the valley over flowing to next and so on, and will eventually travel down front side of block.Your pics of valley were taken very high too high IMO, the holes in block on either side of valley are very low, well below knock sensor plug brkt location. And can be very difficult to see without nose and knock brkt removed. Also as to the rattle if its anything like one of my 3 08 S6’s, it is probably loose and or missing IM internals, all 3 of mine had very different sounding IM noises which had me always 2nd guessing my original diagnosis… Sounds like timing chain slap, loose/missing chain guide issue, worn/collapsed lifter/cam, or piston wrist pin slap/knock, Low and behold every time it was IM.