2002 X5 4.4 - Intermittent whirring/warbling noise

[Rob5]

Trying to describe a noise to search the forum for is nearly impossible. So many different posts about different kinds of noises that I'm lost so I'll just ask if anyone has any ideas.

There is a noise that has started occurring very frequently but not all the time. Its coming from the front end and sounds like a rubber whirring sound, maybe like a rubber belt slipping? It occurs mainly at slow speeds and coming to a stop. It only happens in drive, as soon as park is engaged it stops immediately. I cant seem to find a pattern with the occurrence, it comes and goes every few minutes.

I read a post about a prop shaft donut. I know I've been missing a prop shaft bolt for a while and the car has been vibrating at exactly 60mph for a while, possibly because of this. Any ideas folks? I'm not amazingly technically minded so really need to know if Im causing any damage by driving it and how big a job this mught be.

EDIT: Would this have anything to do with the air con or heating system. I recently changed the 3 red dots to the 3 blue dots and used the air con for the first time in ages. It is since then that the noise occurred. Just changed it back to the red dots and heaters back on and no noise on a short run out. Maybe coincidence?

Thanks in advance!

[davesavage257]

There are two accessory drive belts on the V8, one for power steering and alternator, the other for the air con compressor.  Maybe the air con one is shredding, will sound like a flailing noise.  I had the air con one go, and it got jammed under the other one and was making a racket. Changed both, sorted.
Don't like the idea of driving round without a propshaft bolt, can't be doing the doughnut coupling any good!

Dave
2003 BMW X5 4.6iS Auto
2007 '57' Saab 9-3 Aero 2.0T Auto

[Rob5]

Ah thank you. Would this drive belt stop when I placed the vehicle in park? I've told the garage to replace the missing bolt twice now and both times they've been sidetracked by bigger issues.  >:(

[davesavage257]

Can't think how the drivebelt for the aircon would be linked to the transmission position, so probably not that, sorry. Worth checking though?

Dave
2003 BMW X5 4.6iS Auto
2007 '57' Saab 9-3 Aero 2.0T Auto

[LooneyLeon]

[quote="Rob5"]
Ah thank you. Would this drive belt stop when I placed the vehicle in park? I've told the garage to replace the missing bolt twice now and both times they've been sidetracked by bigger issues.  >:(
[/quote]

No it wont he must not have read the park bit.

All the belts spin when the engine is turning regardless if its in park or not.

With the engine still running put it in neutral what happends then?