[V6-12v] Very Mysterious Oil Leak

[Jamescarstuff at aol.com]

I've watched my (very good) mechanic a couple of times when he's tracking 
down difficult oil leaks. The first thing he always does is go round the engine 
with a screwdriver and an inspection lamp. I've noticed that, unless it's 
painfully obvious where the leak is coming from, he generally starts above and 
works his way down. That way, he's eliminating each 'level' of seals as he goes 
down. Since oil will tend to run down, gravity being what it is, he can, for 
example, eliminate the camshaft oil seals, then the rocker gasket, head gasket, 
etc. until he comes down to a level where the leak is apparent or worse below a 
certain seal/gasket line. It makes sense. It's also generally true, he tells 
me, that a leaks spray pattern, if it's one that goes right to the underside 
of the car, will generally only blow backwards from where the leak is, as the 
car is generally only driven forwards at high speed. This also makes sense, and 
yet I hadn't given it a lot of thought until I watched him go through it and 
explain his methodology. It was thus that he pinpointed a hard to diagnose 
leak (which I'm sure many people on the list are now painfully aware of) from the 
little 'o-ring' under the intake manifold. I was afraid it was a head gasket, 
but he went all around it with a lamp and screwdriver (the screwdriver is 
only used to scrape a little bit of oil up from innaccessible places to see if 
it's 'dry' or 'wet') and said, no - above the head gasket line is dry. So, 
before we even knew that seal existed (it was when I first bought the car before I 
had any manual, or had found this list) he was looking for another seal under 
the intake manifold, and said - yeah, there'll be a little o-ring on top of 
the block, go to the Audi dealership and look it up on the parts system. Sure 
enough...

Good hunting!

In a message dated 5/7/04 5:48:44 pm, mancubus99 at hotmail.com writes:

> I am experiencing a very strange oil leak.   When the car is parked on a
> slight slope with the nose pointing downward, I come back to my car and find
> a puddle of oil.  I.E. a grape fruit sized spot is obtainable in just a 1
> hr. period.  If I park the car with the nose facing uphill there is no oil
> leak whatsoever.  I can leave the car parked for days and not experience a
> single drop.  If I turn the car around it will start dripping immediately.
> I've tried to take a look to see where the oil could be coming from but I
> don't see any obvious signs.  From under the car, the leak appears to run
> off the front of the transmission. There are some dark spots on the engine
> block but they appear to be oil mixed with dirt and not the fresh stuff I'm
> seeing on the ground.  I've checked the engine oil level and the leak does
> in fact affect it.
> 
> I'm calling on the collective wisdom of this group to help me figure out
> this mystery.  Does anyone have any ideas as to what would cause this?
> Where I should start looking?
> 
> TIA!
> 
> Trevor