My alternator bearings have started to do a wife, i.e. whine, so I need to replace them.I was quoted £250 for a new alternator. Although a search will maybe find them a bit cheaper anyhow I decided i could do the job. The alternator is of my 98 Griffith and it is a Magnetti Marelli item with the following identity: 63321353  06-98\A (D.O.M I presume) A127IM - 100A A Company called 'Simple Bearings' provided the items, heres my log of Changing them.

Manetti Marelli

The Bearings are No's 6003 and 6303.

The job takes about two and a half hours.

First, remove the grooved pulley wheel by using a 24mm socket with the pulley held in some stilsons (suitably cushioned to protect the grooves) or other such device. The pulley can be pulled off with your hand as it is simply held tight against the inner race of the forward bearing; there are no splines, keys and the shaft is not tapered.

Remove the four nuts that hold the plastic cover in place. Remove the cover. Once this is removed you can remove the plastic brush/holder assembly which is attached by three nuts (you may want to change the brush/holder assembly at this point) Check the copper contacts of the rotor, they also wear.

Before you can split the two halves of the casing you need to de-solder the windings from their posts (there are three of these); a small gas torch does the job. As the solder melts open the crimp of the posts with a small screwdriver. Once they are free you can remove the four long studs that hold the two halves of the casing together. Remove the front casing.
Either use a press to remove the rotor or support the rear casing and use a copper/ali drift and hammer. Don't allow the rotor to fall. . . . . that'd be dumb wouldn' it. It all came away easily; hardly an interference fit. You can see the de-soldered windings in the shot below.
This is the larger bearing (6303). Remove the four screws from the bearing retaining plate; you can then push the bearing out with your thumb; again, it wasn't a tight fit. Note once again the de-soldered windings at the 2, 5 and 7 O'clock positions.
Here's the rotor with Bearing 6003 still in place. You probably won't have a puller for this, and this one IS a tight fit!. I used a dremmel with a cutting disc. First cut through the outer race and cut a groove in it 180 degrees around from that position. Break it off with a hammer and a flat tip cold chisel. Do the same with the inner race but don't cut all the way through for fear of damaging the shaft. Make sure you have someone to hold the rotor firmly and squarely on partially opened jaws of a vice. The shaft is relatively soft and can be bent; you don't want that to happen. . . . that'd make you double dumb!
Job done. All rotating smoothly. . . . lovely.

Whilst I was going about this job, I thought I'd take the tensioner pulley along to the bearing supplier as it'll have done a fair few revolutions over 57,000 miles. The plastic pulley is actually formed over the bearing and cannot be removed. Unless you cut away one of the retaining lips integral to the pulley that is. Loctite 6401 bearing adhesive was used to bond the bearing in place. The bearing is No. 6203.

Should you wish, you could peen over the edge with a soldering iron for that extra piece of mind. Bearing Boy seemed to think there'd be no issues however and neither do I.

I cracked out 100 miles earlier today and all is good, quiet, smooth and the alternator is charging as it should.

O.K Sorry about the photo quality.

Oh, and clean up the kitchen worktop up before the wife sees wotcha been doin'! Tripple dumb!

Bruce ( 2Munkys ) 

Chimaera owner Simon ( That Daddy on PH ) adds, the 6203 bearing is a common motorcycle wheel bearing(front usually)about £4 (a guy was selling them on Ebay some time back under Rover V8)and you can purchase from places like Watling Tyres etc or a bearings outlet.