I have a 2003 Audi A4 Avant 1.8T 5speed Manual Quattro. 130,000 miles

My car has developed a rattle that seems to come from the engine. Here are some details of the sound...


-sounds very similar to a failing water pump - it's loud and very audible

-rattle gradually comes as car is warming up. There is no rattle upon startup.

-When car is fully warmed up, the rattle occurs only at 1500 to 1900RPM

-engine sounds perfectly fine at RPM lower than 1500 or higher than 1900RPM

-no change in power is detected while driving.

-No check engine light

-Upon opening the oil filler cap on engine, sound definitely comes from the inside of engine.
It sounds like something is very loose.


I don't think it is a water pump or failing alternator clutch because the sound is not coming from that area. Also, I changed the H20 pump, timing belt, tensioner, and pulley 25,000 miles ago. It sounds like it is coming from the timing chain area, but doesn't that tend to make MORE noise when it is cold and at startup?

Does anyone have any ideas about what this could be? It sounds pretty bad even though the car drives perfectly fine. I don't even notice the rattle until I open the windows. However, once the windows are open, the rattle is VERY evident.

I know this is not a great way to diagnose a potentially big problem, but once again, I have to start somewhere...

Thanks!!

 

Here is a Youtube link to a video of the problem...

http://www.youtube.com/watch?v=D6TcHPRG0X8


Or, you can link to a higher quality video on my MobileMe page...

http://gallery.me.com/jinsoo.joo#100207/Audi%20Tapping



Could this be a sludge issue?



Thanks!

 

Perhaps I'm just posting messages to myself here, but I know of one other person out there with a 1.8T that had this same problem. So, I'm posting my solution in case anyone else runs into the same issue...

My problem was a faulty timing belt tensioner. The piston on the tensioner leaked and was no-longer pushing against the pulley / damper firmly enough to tighten the t-belt. This caused a rattle in what I suspect was the pulley where it normally connects to the tensioner.

I replaced the tensioner and decided to replace the pulley in case there was wear from the rattling.

The noise was gone!