moribundman

I spent a couple hours under the car today, checking for various noises and most of all one (2? 3? 4... ?) oil leaks.

I found one: The passenger side valve cover gasket is definitly leaking towards the side of the car.

But the major source of leaking oil seems to come from under the manifold. The coolant hose that comes out from under the manifold at the back of the engine is wet with oil, and oil drips down the back of the engine, mostly on the driver's side, where it speads out and soils not only the engine, but also the tranny.

An idea if the leaky valve cover could get the coolant hose under the manifold wet with oil?

JWG

Inner side head gasket leaks may easily occur with taking off or torquing the intake manifold, because it pulls up on the head. When this happens it has two effects: (1) oil leaks from the inner side of the head gasket and (2) the oil often contaminates the cooling system (as the oil system has higher pressures than the cooling system and the higher pressure fluid will naturally go into the lower pressure system). To fix this problem, the Bentley manual suggests giving the head bolts a 1/4 turn while you have the intake manifold untorqued. After tightening the head bolts, then gently torque the intake manifold down precisely to specification. It worked like a charm for me, quick hour or two fix if you have the head bolt triple-box socket tool and 6mm hex socket.

Valley pan gasket leaks occur due to the gasket getting old and cracking due to high heat--it sits right between the engine banks and above the crank. Audi should have used a full metal gasket on this part, but its just regular "sandwiched" gasket materials. This is a usual PITA replacement, but you can do it in a few hours, if you know how to take off the intake manifold. However, I would first spray the area clean with pressurized hot water or steam, because you will have an aweful time cleaning up down there after you take the intake manifold off; too many opportunities to get grime all over the place and too difficult to clean up with just rags (please pull plug wires and fuel injector wires before you spray and cover the rest of the electronic parts under the hood).

I had to have the under side of the car steam cleaned ($25) to find the source of the leak, because, as you noted, the oil coats everything as it flys back off the engine.

moribundman

My coolant is still clean, so I'm hoping it's not the head gasket. Too bad it's almost impossible to see anything on this engine without removing major components.

The valley pan gasket would be #14 in the exploded view?

<img src="http://194.87.53.210/imaudivw/small/VAG034E4.gif">

JWG

--#15 is totally flat with no connector on the AFC version of the 12v.

In most cases your head gasket will still be fine--especially if you have no oil in the coolant. Only the torque values get screwed up and allow fluids to seep out of areas where there is not adequate pressure on the head gasket to form a tight seal.

moribundman

It's not like they give us a final figure in ft-lbs. It's x ft-lbs plus a 180-degree turn or something.

How can you even figure out if a bolt is too loose (unless it's REALLY loose!)?

JWG

basically you just torque down the bolt further and make it strech a little more.

However, you can tell whether the head gasket is leaking: get a powerful flashlight and focus it in its narrowest beam under the intake manifold through the small holes in front, behind, and in the middle of the intake manifold. From your vantage point, you should see the head gasket sticking out under the head--it looks kinda brass/copper in color and sticks several mm beyond the head. Look for the bottom lip of the head and you should see a small copper "step" before the blackness of the engine block and valley pan area. This is the head gasket. If it leaks inward toward the valley between the cylinder banks, you will see oil seeping from that small step. If not, do not worry about it.

Remember, if you have never removed or unbolted your intake manifold, you should have no problems with your head gasket. Focus on the valley pan gasket first and to prevent future problems with the head gasket remember to gently and precisely torque down the intake manifold. My problem resulted from my misreading the torque wrench, I intended to use Newton meters and ended up using lbft when I torqued it down; thus, a difference in five lbft can lift the inside of the head and cause a leak at the head gasket.

moribundman

In case a head bolt has stretched or become loose, a 1/4 turn might not be enough (or too much?). Or am I overthinking this? ;-)

As for the manifold having been removed:
Yes, my mechanic removed it once, and just a couple months ago I found out that the bolts were not torqued correctly. Some were only finger-tight... I can only assume that some of the others may be over-torqued. I bet he used his calibrated elbow.

Quite frankly, I'm not sure how I you can manage to see the head gasket under the manifold. Short of using an endoscope I'm not sure how to get a good look under the manifold and at the head gaskets.. Maybe if I remove the coil pack I can stick a mirror and a light in there. And yes, I know how a head gasket looks... ;-)

Anyway, I'll replace the leaky valve cover gasket first. Although I may have to do that again in case the head gasket is due, too. Thank God I'm good with tools.