dfinnegan

I'm tracking a noise from the rear. I can't quite tell if it's a CV joint, the fan/alt bearings, or something more sinister.

In the process I've discovered rub marks on two quarters of my engine fan housing. Note that I inadvertently let a paper towel get sucked into the fan some time back. It got pretty well jammed between the fan blades and the housing and may well be how the rum marks were made.

I've pulled the alternator assembly, removed the housing, removed the fan, and its bearing and am down do the alternator, itself, with its small in-bound fan in place.

The engine fan bearing seems to be fine. No noise, feels smooth, no shifting in any direction. I think I'll reassemble with the old fan bearing; unless, of course, you lot feel that it's prudent to replace it as preventative maintenance.

The alternator bearing, on the other hand, does not sound or feel up to par. It makes a grinding, gritty sound as it turns (phone video out of action, but will try to post a sound clip later). The shaft of the alternator also has some slight play in it along the axis of the shaft.

I'm thinking that the alternator bearing needs replacing, but can't tell if it's the in-bound our out-bound bearing; nor how to get at them. Do I pull the alternator apart? I have no impact wrench and am thinking that it'll be a bit of a trick to get the small fan off the shaft.

Also, if I'm keeping this alternator I'd like to replace the bushings. Are these serviceable, or does the entire brush assemble get replaced?

A couple of pics follow.

Thanks,
Dave

dfinnegan

Adding video with sound clip of alternator bearing and a look at the fan shroud markings.

Note that the alternator brushes are out in the video, so the sound is not them rubbing.

Note, also, that the fan blade ends do not show any sign of rubbing, so those marks are not likely the source of my elusive noise. I'll try and get a clip of that sound, but it always stops before I can get stopped and out of the car.

Fan bearing noise

Fan shroud markings

Rocket Rob

You can loosen the nut to holding the small fan by holding the shaft stationary with your 12 point wrench onto the alternator shaft on the opposite end.

Haven't yet watched your videos.

Rocket Rob

the videos helped. The alternator bearings sound worn/shot. I would consider replacing or rebuilding the alternator. I bet that's the cause of the wear spot on your fan housing.

My car had a similar fan rubbing the shroud sound but the fault was not the alternator but the fan pulley bearing. While I had the housing out, I sanded it and sprayed it with black satin spray paint.

dutchcrunch

looking at the brushes tells me there was plenty life left. bearing failure is usally a result of belt being too tight.

dfinnegan

Solution: turned out to be my spoiler drive worm-gear mechanism. I had R&R'd the drive a few years ago and the worm-gear mechanism had come partially apart allowing the square drive cable to rat-a-tat-tat when trying to lower the spoiler when approaching stops. Whew.

Oh, and the alt/fan bearings were fine. I now have a spare alternator.

MAHack

I once had an early 911 alternator rebuilt at a local electric shop. They didn't even ask what it was out of since they are all pretty much the same. In two hours they pulled it apart, tested the windings, replaced the front bearing, turned the commutator shaft to make it shiny again, and replaced the brushes. Then it was put back together and tested.

Total cost....$50


-Mark

dfinnegan

Yea, I paid a bit more for a rebuilt from Pelican. Then I ate the core charge. Me an money are not the best kind of friends.