My 2006 A4 Quattro Auto 2.0T (46,000 mikes) has been making a strange rattly noise at startup. It's definately more prominent in the morning when starting from cold but that may be that I'm in the garage and so the noise seems louder. That said, I've also heard it when starting the car at work in the evening. The noise, which lasts maybe a second or two, sounds like a bag of bolts being poured into an empty paint can and I'm pretty sure it's coming from the engine bay. It occurs amost immediately on turnover of the engine and not during the first few key positions when there are several other less traumatic clicks and whirrs... it's only in the final position when the engine fires up. If I was to guess, it sounds like the hydraulic lifters were waiting for oil but I've never heard anything this noisy on any car I've owned before. If the car is warm at startup, it doesn't seem to do it, or not that I've noticed. It never makes the noise at any other time than in those first few seconds.

Any ideas...?

 

There was a suggestion on another forum that it may be related to the starter... maybe the starter drive pinion isn't disengaging quickly enough or something like that...? Here's a video of the problem and it does indeed occur after the key has been released from the start position just after the engine has fired up (around 27 seconds).

http://www.legoheads.com/AudiStart.avi

 

my starter also has sticking issues with the throwout - apparently its common on these engines inc . golfs. The throwout bearing gets clutch dust and muck in it and it sticks a bit, the noise is the relative high-speed that the ring gear is turning at when the engine starts, throwing the starter pinion back into its home in the stater motor.

 

Theres actually a TSB that describes this as normal. I mean i think you would need an Audi tech who has experience and listens to these engines start and run all day to have the final word.