Alternator Bearings

[sotal]

I've posted this on another forum so apologies if you've read it twice...

The bearings have gone in my alternator, are they changeable? If so how do I get them off/out?

I've attached a picture to show where I'm up to - one bearing can be seen, the other is in the casing at the top

[simonb]

I've posted this on another forum so apologies if you've read it twice...

The bearings have gone in my alternator, are they changeable? If so how do I get them off/out?

I've attached a picture to show where I'm up to - one bearing can be seen, the other is in the casing at the top

For 200/300Tdi:

To get the brush end one out, heat the casing gently around it with hot air gun or blow torch and knock through from outside in with a socket. Support the inside around the bearing carefully or the end cap may crack....Do not just rest the cap on the bench. Refit new bearing to same depth as old one from outside inwards. Heat casting first.

The top one is more of a PITA. Sometimes a careful sharp blow to the end of the shaft protecting the threads whilst supporting the casting on wooden blocks will push the shaft through the bearing centre. Its then a case of tapping the bearing through with sockets and supporting the centre well. Again do not just rest end cap on bench and wallop it.

However, what usually happens is the whole lot is jammed solid. The only way then is to use a large 3 leg puller to pull the end cap of the shaft. Even then the force needs to be applied and the puller legs tapped round in turn with a hammer whilst tightening the centre stud. The puller legs will ring then sound "dull" as it slackens off. Tough ones can take an hour to free off...

When refitting the top bearing heat casting and support as knocking in the new bearing. Put a dab of locktite on the bearing outer before fitting. Throughly clean rotor shaft and it should just drop in. Then drop that lot into body. End float will be sorted out when pulley is refitted.

For your one:

Brush end bearing can be removed with a split puller after the slip ring assembly has been removed (with same type of puller). You will need to unsolder the rotor windings from the slip ring. A 50/100w soldering iron will be needed to do this.

[sotal]

Thanks for the reply, so for mine (it's off a series 3 engine - 1984) The top one is the same as the disco and should just tap out? I've tried a few gentle taps but didn't want to force it incase anything else held it in.

And for the brush end I'm not quite sure how to go on. Right at the end is a slot which looks like you could put a straight screwdriver in it, next is a black rounded rectangle - no idea how to remove that, then the first bit the brush rubs against (I presume that's the slip ring) I can see that needs to be unsoldered. Then I need to remove that with a split puller? unsolder the next one and remove that with the split puller - then remove the bearing with the split puller.

Then with the brush end do I just replace the bearing by tapping it on, then the same for the slip rings obviously soldering them as I go?

[simonb]

Thanks for the reply, so for mine (it's off a series 3 engine - 1984) The top one is the same as the disco and should just tap out? I've tried a few gentle taps but didn't want to force it incase anything else held it in.

And for the brush end I'm not quite sure how to go on. Right at the end is a slot which looks like you could put a straight screwdriver in it, next is a black rounded rectangle - no idea how to remove that, then the first bit the brush rubs against (I presume that's the slip ring) I can see that needs to be unsoldered. Then I need to remove that with a split puller? unsolder the next one and remove that with the split puller - then remove the bearing with the split puller.

Then with the brush end do I just replace the bearing by tapping it on, then the same for the slip rings obviously soldering them as I go?

Top bearing sounds like it needs a puller.

Slip rings sound like they will need to have the bottom plastic bit removed, that should expose a solder joint, bottom ring can then be removed which should expose the joint for the upper one, but you will need a new slip ring set for reassembly. Frankly for a series 3 which is only a 30A version i wouldn't bother. A new exchange unit from Halfords will only be about £40.

For a 65A/100a Tdi unit its worth doing and since the bottom bearing is in the case the slip rings don't need removing. Put it all back together and get an exchange one. if you take it to Halfords they will (usually) even fit the fan and pulley back on the new unit with the rattle gun.

[sotal]

I've got to say I think you're right - although I have been told that there's a place nearby that will recon them for £15 so I might give them a bell first.

Thanks for the help