For the last 6 months or so, my '04 XJ8, 40K miles makes a squeak on startup. The squeak is not continuous but repeats about every 1/2 second for about 5-10 seconds and then goes away. It is not the loud belt slipping kind of squeak, and will not repeat itself if you stop and re-start the car. You need to leave it for 3+ hours for the noise to re-appear. It seems to be independent of whether the A/C is on or off. Since it only lasts for a short time and is not really repeatable (unless you leave it for many hours) so the local dealer havenot managed to trace the source.

Everything is working fine so this is more of an annoyance or preventative maintenance issue that a hard fault. Having said that I would like to get some thoughts from other board members on what may be causing the noise. I'm thinking it may be the water pump, but what else do you all think it could be?

Thanks

- Tim

PS - I am thinking about recording the noise with my cell so the dealer car hear it more clearly and could email the MP3 file to anyone who is interested!

 

well i had the same problem with my ML55 AMG back in time, after a year my friend figured it out it was coming from the water pump. But at that time my car had over a hundred thousand miles on it so it was time to replace it, but somehow he fixed it and noise was gone.

 

In my experience with other car lines this type of noise on a cold start up is often a idler pulley or wheel on the drive belt.

 

there is a bulletin for updated belt tensioner and idler pulley and belt for noise