Help! S8 Scary Engine Noise...Worried

[mark_le_b]

Hi all

My 2002 S8 has developed a worrying engine noise.....any idea what it is?

Not even sure if its safe to drive to the indi!

Sounds like top left of engine as you look as you stand in front of car

Link below can be cut and pasted into browser to listen

Thanks
Mark


http://youtu.be/rhE6tbx_cw8

[David's8]

I presume that the revs were steady at tickover throughout that clip? Does it change with revs?
If I remember you dont have VCDS?

[ainarssems]

Hard to say from video but it could be secondary air injection pump if the noise come from air filter box area in which case you could just temporarily disconnect it. If you have VCDS you might be able to test it using output tests or as Audi call them final control diagnosis.

[mark_le_b]

Originally Posted by David's8

I presume that the revs were steady at tickover throughout that clip? Does it change with revs?
If I remember you dont have VCDS?

Revs are constant - no change, it still revs drives etc., no misfire
I don't have VCDS - but may take car off the road and order it!

[mark_le_b]

Originally Posted by ainarssems

Hard to say from video but it could be secondary air injection pump if the noise come from air filter box area in which case you could just temporarily disconnect it. If you have VCDS you might be able to test it using output tests or as Audi call them final control diagnosis.

I did have a fault code for that a while back (from a hand held diagnostic) - the noise sounds higher up than the air filter box

Noise seems to resonate more when I take the oil filler cap off....

[Goran]

It does sound like some sort of electric fan is constantly on as Ainarssems says.
I assume the electric radiator fan is not turning when you hear the noise?

[mark_le_b]

Originally Posted by Goran

It does sound like some sort of electric fan is constantly on as Ainarssems says.
I assume the electric radiator fan is not turning when you hear the noise?

No fan is not on. I am nor driving it today and am ordering VCDS for myself to see if that points me in the right direction!

[steamship]

Originally Posted by mark_le_b

Sounds like top left of engine as you look as you stand in front of car

Originally Posted by mark_le_b

Noise seems to resonate more when I take the oil filler cap off....

Could it possibly be the engine block breather valve giving up the ghost?

[mark_le_b]

Originally Posted by steamship

Could it possibly be the engine block breather valve giving up the ghost?

Where do I find this and how do I test it?

[Goran]

Originally Posted by steamship

Could it possibly be the engine block breather valve giving up the ghost?

I think you're onto something there! perhaps the rubber diaphragm has failed and is vibrating as it lets air out?

Its the black plastic UFO type object at the back of the engine.

Here it is in a picture I borrowed from another forum member's post as it shows the engine bay without covers.

It is easy to remove by jubilee clip or the Audi type clip, but I'm not sure if its safe to run the engine without it or with the rubber hose plugged to test if the noise stops?
Probably ok for a minute or two, as its just a sprung rubber diaphragm to let some crankcase pressure out when it builds up enough to be able to open the diaphragm.

This is how it looks inside:

http://forums.quattroworld.com/a8/threads/8649.phtml