B8 S4 - Just audible tinkling noise from engine

[rum4mo]

After changing the oil, I ran the engine to check for leaks at the drain plug and filter housing areas and I was aware that there was a very light tinkling noise coming from the engine bay, almost like a piece of tin plate rattling, any clues at all?

The fact that it was first noticed after an engine oil change is not significant I think as when the bonnet is closed you can't hear anything bad, or in the car - its more that I don't normally open the bonnet while the engine is running, so it could have started any time since last year's oil change.

I've ran the engine twice since the oil change and it is still there.

Without putting any suggestions into anyone's head, what does the bottom pulley sound like when it begins to separate? It does not seem to be any heat shields.

Edit:- other info on that car, it has only run 25K miles and is a Feb 2011 car.

Thanks in anticipation!

 

[Tobe]

See if you can tell if its coming from near the back, if it is could be the upper timing chain tensioners, which are behind the black covers at the back of the head on both sides of the engine. Being 2011 unless they've been changed it probably has the early version that is known to be a bit noisy, normally only when cold and they calm down once warm. There was tsb's for it that allowed a certain amount of rattle before they would be changed in warranty.

I've had a few of these engines all b8 not 8.5 and all did it, with about 1 secs of loud rattle after being left for over a day and then very faint almost un-noticeable without the bonnet open for a little while until oil is warm. Some would panic and say get them fixed but between cars I've had ones that did this for about 30,000 miles overall and never had a problem, not to say they didn't go 2000 miles later after selling, that I have no idea about!

There could be many many other things that it is though but that was the first that came to mind.

 

[rum4mo]

Thanks for replying, I've only just bought another mechanics stethoscope after losing the last one 22 years ago, so I'll get busy with that.

This car can be left for a month or more at a time and while the bonnet is closed, starts up without any unusual noises, my old 2000 VW Passat 2.8V6 did make a bit of a noise now and again when starting up after being left unused for a week or more, it made proper rattling chain noises for the reasons you gave, the noises on this car almost sound like metal flaps rattling or a sheet metal item being loose.

Edit:- BTW I can't say that I didn't consider that but hoped the noises were far to "tinny" to be that.

 

[scotty7519]

Does the engine have an inlet manifold ? I know I had one on my previous S6 that rattled had to change it and they found part of the plastic from the manifold sitting on top of one the valves nearly destroyed my engine

 

[rum4mo]

From the parts listing it looks like there are lower inlet manifolds below the supercharger with associated vacuum units so that will mean flaps and rods.

Also, do these cars have a secondary air pump, I'm sure that I've heard mention issues with them in the past?

 

[scotty7519]

Not sure I know I have had issues on all my Audi’s I have had with inlet manifolds 1st one was V6 2.6 petrol replaced whole manifold as it was leaking air only a couple hundred pounds from Audi. Next one was on the V8 4.2 the control arms broke for the swirly flaps a common problem. Then had S6 5.2 V10 3.5k to replace inlet manifold had a rattle plastic gubbings inside broke found small part in top of a valve !! Could of been a disaster but any rattle I would get checked out it was a friend who works on rally cars who discovered the rattle when he tested it after it been fixed for something else so was very lucky. So I’d check the inlet manifold with your stethoscope if the rattle comes from there then I would advise against driving the car as if it has broke then any small parts could fall into the valves.

 

[rum4mo]

Yes I don't intend to drive it until I look into this, unfortunately the short inlet manifold sections are below the supercharger, so no access for me to that area without removing the supercharger. I'll try to find the secondary air pump if UK cars have that and disconnect its supply, I think that that air pump, if fitted only runs for a short time after a cold start.