Ticking or trembling noise from enginebay

[Peer81]

Hello everybody,

Hopefully somebody overhere knows this sound as I have an idea but don't know for sure.
The sound started very faint and in the background but it becomes stronger over time. I only hear it when the engine is cold and after 5 minutes it fades away.

I hear it very clearly from under the car and not so loud from above. I was thinking it could be a loose rocker but as I checked the valve cover and exhaust with a screwdriver listening I could hear the noise inside the engine. Also I have the idea when I stop the engine the sound will stop a few second later but I'm not sure if I heard this correct.

Thanks!

http://www.youtube.com/watch?v=digD0tB7OGg

Greetings Peter

 

[JohnZ]

Hello everybody,

Hopefully somebody overhere knows this sound as I have an idea but don't know for sure.
The sound started very faint and in the background but it becomes stronger over time. I only hear it when the engine is cold and after 5 minutes it fades away.

I hear it very clearly from under the car and not so loud from above. I was thinking it could be a loose rocker but as I checked the valve cover and exhaust with a screwdriver listening I could hear the noise inside the engine. Also I have the idea when I stop the engine the sound will stop a few second later but I'm not sure if I heard this correct.

Thanks!

MVI 2489 - YouTube

Greetings Peter

That internal noise and its symptom (loud at cold start and fades away in 5 minutes) is consistent with piston slap; lots of C5's had it, and there were several C5 TSB's on it.

 

[Peer81]

As I have hyper pistons and not forget I don't think it's piston slap, it also just appeared a few months ago as I believe.

On the dutch forum I get comments on loose converter bolts, leaking lifter or rocker clearance.
I'll restart it again this week and look at it again.

Greetings Peter