Audi a7 black edition 3ltr quattro rattle at start up now and again advice needed

[Jonesy76]

Hi all ive recently purchased a 2014 audi a7 black edition quattro with full service history ive noticed at start up only now and again there's a rattle for a couple seconds then completely goes it only does it at start up now and again is it anything to worry about any advice would be greatfull thanks

 

[+robster+a7+tdi]

ive wondered about a similar thing and its very rare usually when very cold and i put it down to initial start timing having to adjust to the ambient temperature as it clears instantly within a second or two . gosh knows it would be interesting to know if it is related to a start up after not completing a dpf regen cycle or something as its random ive only experienced it about 6 times in 2 years so nothings worn out but rather ecu is adjusting timing or fuel quantity or a valve is getting filled with oil to operate something correctly or could it be a sometimes sticky/ lazy inlet manifold runner /swirl flap or throttle flap causing air starvation??? guess we will never know lol

 

[+robster+a7+tdi]

i may be over thinking things above
See picture this happened tonight about a quarter of a mile away from my destination
slip joint clamp has rotten / failed and slid back over the rear section of exhaust that is thankfully suspended to the exhaust hangers - well the clamping part of it anyway has failed and the tube part is ok.
i slid it back over to go where i was going then return home but it could slide back at any time.

Im hoping this may explain the rare elusive rattle on start up and the rare clunking noise when the car bumps up onto the kerb ( i was checking all the front suspension and arms etc but could not fault anything )

 

[+robster+a7+tdi]

Worth noting . The exhaust sags and sometimes hits the cross brace if the joint has gone.