LOUD squeeling noise from under the hood...

[C Murda]

my 89 325i is making a really loud squealing noise and i cant tell what it is. the belts are still good and seem tight and when i rev the motor up it will go away but once the motor comes to idle or if im coming to a stop it will slightly squeal sounds kinda like a bad bearing or somthing and then when i go to accelerate it gets horribly loud until a certain rpm when it goes away completely. could it be my fan clutch?

[bmw325csi]

My vote is water pump.

[C Murda]

^^^ is this a typical problem? Would a water pump from an 87 325 2.7 work?

[Gruelius]

id guess water pump. easy way to check fan clutch is to take it off and see if problem persists.

Also waterpump will have water seeping out of the weep hole if the bearings are toast. not allways tho so if it does end up being the pump replace it.

[slammin.e28]

Yes. Water pumps go bad from time to time. Cross the P/N on realoem for the waterpump. I don't see why M20 pumps wouldn't cross...but just in case.

I would do the timing belt while in there, unless it was done very recently...in which case the waterpump should have been replaced....while in there.

[MTechnikII]

once you change the waterpump even if you have a new belt there go ahead and put another new timing belt, once you re install a timing belt chances are that it might break sooner.
one more thing, is your 850i 6sp as fast as i'd imagine? being V12 and 6 sp?
Henry

[RickSloan]

no the water pump from the 87 will not work with the 89. The 89 has a metal cooling pipe a cross the front of the motor and the 87 does not. The pumps are not the same

[Gruelius]

yeah also early ones had 2 inlets on the pump not just one

[jlevie]

Remove all of the v-belts from the engine and see if the noise is still present. You won't hurt the engine by running it with no water pump for a minute or so with the engine cold. If the noise is gone, check each or the rotating parts for bad bearings. If the noise is still present with the belts off, the cause is the idle pulley on the timing belt tensioner.

[C Murda]

thanks for the help guys... im gonna try removing the fan then the belts and see if the noise is still there hopefully it is something simple.

once you change the waterpump even if you have a new belt there go ahead and put another new timing belt, once you re install a timing belt chances are that it might break sooner.
one more thing, is your 850i 6sp as fast as i'd imagine? being V12 and 6 sp?
Henry

^^ its quick up top but definately not really fast being such a heavy ass car but boy does she ride like a dream! and the subtle rumble of that motor sounds very nice