just my thought..
OK. I have an awfull kia mentor. Long story but I have ended up with it.
Long list of MOT fails but most are done. I think its been in the sea.
Thing is the alternator squeals when its connected. I mean when the wires are connected not the belt. when I unplug the alternator there is no
noise.
Any ideas?
Also if anyone is looking for a shi...uperb kia mentor get in touch.
silly question .. but have you tightend the belt up to see if it goes away? I mean unpluged means no load on the belt cause when it generates curent
it puts a load on the pully... no conection=no load=no squeal....
just my thought..
Now there's a novel idea
.
Get a new belt - easiest way, you know it is! You'll end up doing that in the end, probably after the one that is squealing right now snaps and
leaves you in the lurch. It makes perfect sense whilst you'e working on the belt to renew it doesn't it?
Oh - did I say replace the belt? 
has anyone looked at he time 
2.30 in the dam morning.... mtv and kit cars!!!
I know, I though about an early night around 10, what am I still doing up?
Squirt the belt with a bit of water from a spray bottle, if the squeak goes, it's the belt slipping.
I might be wrong on this but doesn't running an alternator without it
being hooked up to a battery blow the diodes inside it?
I know next to nothing about electrics so I hope I'm wrong,
but for some reason I'm on my second alternator. 
Paul G
It can do if run for ages like it.
Squirt the belt with WD40 or water. If it goes its the belt.
AS said above unpluging it will only remove the drag on the belt so even a slack belt wont squeal. The belts probably gone hard.
Under load it will squeal. Tighten the belt till there's absolutely no play in it anywhere then try it, not like the old dynamo.
running an alternator un-plugged will kill it,
if the belt is ok and tight enough,check the charging rate,if the reg has gone and its charging flat out the belt wil slip,the battery boil,the
alternator explode and mankind shall cease to exist as we know it
I have put in another alternator and the squeal is still there, its had a new belt has been degreased, along with the pulley and has been tightend up
and it still squeals?
I'm stuck.
If the car would explode when running with with the alternator unplugged maybe I'll just do that.
Could be fun.
Might sound daft but is it the water pump bearings or any other pulleys that the belt comes into contact with, and just happens to sound like its the alternator?
The water pump was changed yes. Would that be right that when the alternator is connected the water pump could cause the squeal?
quote:
Originally posted by MkIndy7
Might sound daft but is it the water pump bearings or any other pulleys that the belt comes into contact with, and just happens to sound like its the alternator?