Noisy Alternator when idling

Hi,
my alternator makes a loud rattling, almost grinding noise when the motor is idling. It is silent when the rpm increases and functions well. Can anyone suggest a remedy? Thank-you.

Bearings worn out. Hope for your sake you fix it B 4 the internals touch and spread steel dust through the works. REBUILD OR REPLACE NOW.

Originally Posted by bmwfatherfigure

bearings worn out. Hope for your sake you fix it b 4 the internals touch and spread steel dust through the works. Rebuild or replace now.

+1

Originally Posted by BMWFatherFigure

Bearings worn out. Hope for your sake you fix it B 4 the internals touch and spread steel dust through the works. REBUILD OR REPLACE NOW.

+1,000,000

Replace or rebuild

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Originally Posted by BMWFatherFigure

Bearings worn out. Hope for your sake you fix it B 4 the internals touch and spread steel dust through the works. REBUILD OR REPLACE NOW.

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Thanks.
BTW - is replacement an easy DIY job ?

Originally Posted by CraigBMW

Thanks.
BTW - is replacement an easy DIY job ?

Yes. I would suggest you either purchase a hard copy of the Bentley manual, or you can search this website for a link to a site where you can download it.

Thanks.

Originally Posted by CraigBMW

Thanks.
BTW - is replacement an easy DIY job ?

Remove fan (reverse thread) and shroud
Remove belts (allen key tensioner)
Unplug/Unbolt

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You guys have covered it all...

Make sure its not just the nearby inexpensive idler pulley thats near there ,that tends to get loud when its bearings fail. Just spay the affected part with Wd 40 to identify what part goes silent , instantly after spraying.

Luckydog, you are spot on, the idler pulley is the problem. Thanks a million.

Do the hydraulic tensioner conversion.

I strongly recommend it

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Replacement of the idler pulley would appear to be a simple job. Any traps to be aware of ?

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Monsignor, what is the hydraulic tensioner conversion ?

Our m50 machines came with a spring tensior that wears over time. M60 cars (540 and 530 (v8) cars) and m52 (e39 525, 528, amd 530) cars came with little hydraulics for tensioners. They are much more reliable, resiliant, and easily serviceable. They make bolt-on kits for the conversion. I got mine from ECS after my spring tensioner blew, ate both belts, shattered my water pump pulley and busted my water pump. Drivig down the highway at 70 and losing power steering sucks on top of the waterpump.

Busted tensioner thread

Preventative maintenance.

ECS Hydraulic conversion kit

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Thanks Monsignor, will look into it.

Updated previous post with coversion kit link

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Cheers, Thanks.

I recommend that you remove the serpentine belt and check all pulleys and items operated by the belt.

EDIT: I missed it above that you found the problem to be the idler pulley

Change the belt too....

interesting, my M52 that i put in my E30 had a spring type setup.

The hydraulic tensioner kit looks like the ideal set-up, but I'm not sure about availability and cost in Australia. If replacing the idler pulley with a new original, would the consensus be to replace the (spring) tensioner at the same time (as well as the belt) ?

Originally Posted by _Ethrty-Andy_

interesting, my M52 that i put in my E30 had a spring type setup.

silly kiwis