Strange noise.....
 

http://img.photobucket.com/albums/v5...8/100_0253.jpg

After taking a drive today, I noticed that the car was making a strange slightly clanging noise. I thought it was from the muffler or exaust, but after opening the engine compartment, I noticed that it seemed to be coming from the large fan.

It can only be described as a tinny, clangey metallic sound. And I only hear it a low revs or idling at a light.

Any help is greatly appreciated. Thank you…..in advance.

is it the belt tensioner?

Yikes! That doesn't sound good. Where is it?

Is there any way
of testing for an alternator bearing failure, without removing belts?

Good question, I don't know.

If it is the belt sensor, it is no big deal at all. They do tend to squeak.

http://p-car.com/diy/roller/

Try this: With the car off (and cold, so you don’t burn your hands), push the roller away from the belt and then see if it spins easily. If you feel friction, or when you spin it, it stops quickly, it’s time to replace it. I tired the oiling trick a couple of times. It only lasts so long… New sensors are cheap and easy to replace.

It's called a "belt tension sensor" on this page:

http://www.pelicanparts.com/cgi-bin/ksearch/PEL_search.cgi?command=show_part_page&please_wait= N&make=POR&model=911L&section=ELchrg&page=1&bookma rk=4&part_number=993-106-035-00-M260

It's not so much a squeak, as it is a hollow, metallic, clangy noise.

It is nearly impossible to diagnose noises over the net. One of the things that can go bad in that area is the sensor. It should be near the top of the list of things to check. That’s about all we can do over the net, is give you a list of things to check.

Do you see some scrape marks on the fan housing?
If you do, fan bearing or alternator front bearing could be going out.
It could also be a glazed fan/alternator belt squeaking combined with a bad bearing.

That could also be a camshaft chain hitting on something due to loose chain or worn guide or collapsed chain tensioner.

Work on the alternator/fan bearings first. It is so much easier to diagnose.
Bad alternator/fan bearings can easily be seen and felt with bare hands once it is on the work bench.

Is it possible or indeed known, for small stones or objects to get past the fan and ping around the tin-work like a roulette wheel?

I know plastic bags can be sucked up off the road on earlier cars without trays