XSeries-forum

Hi all yesterday my E53 4.6is inherited a load screeching/Squeaking noise, It sounded like a pulley had seized but on inspection all wheels were turning. I have located it to the nearside Auxiliary Belt side that goes around the water-pump, power-steering and alternator pulleys. So now I've got to find exactly where the fault is?? 
I've manually checked side play and spun each of the 3 pulley wheels which all spin freely, thus seam to be OK with no apparent problems. I've also checked both the tension wheels, which again seem to be OK also?
So now I'm stumped and looking for some direction as the cost can ramp up by the hit or miss of changing items, that may well be OK.
All help greatly appreciated

Could it just be the belt is stretched a little, what condition is it in? Or the tensioner getting soft?

[quote="Greydog"]
Could it just be the belt is stretched a little, what condition is it in? Or the tensioner getting soft?
[/quote]
Prior to releasing the tension on the belt it looked and felt (tension-wise) OK, the belt looks good had them replaced at the start of the year. I did also release then retension the belt to see if there was any difference, unfortunately no change' it definitely sounded like a rotatory squeal ??

Probably a bearing , alternators tend to scream when the bearings are shot, or could be the tensioner.
Trouble is after you unload the radial stresses on the bearing by loosening the tension on the belt the pulleys may run free as there is no sideways load on them. Very frustrating . If the belt isn't showing signs of fraying or missing rubber, sounds like a bearing.

I agree with Horizon, check for any rocking in any of the pulleys. It only takes a small amount to cause issues under load. The alternator particularly when load comes on when generating current will not need much wear to cause problems.

[quote="Greydog"]
I agree with Horizon, check for any rocking in any of the pulleys. It only takes a small amount to cause issues under load. The alternator particularly when load comes on when generating current will not need much wear to cause problems.
[/quote]
Thanks for the feedback, Yes these I know about and were checked out. The alternator was replaced at the beginning of this year, so I'm hoping it's not that. I think I'll have to purchase a pair of tension pulleys and try them first.