Alternator diagnosis request 1977

[kach22i]

A new and aweful sound from the rear of my car just started Sunday. It sounds like an electric motor noise.

I've since heard the fan belt sweak twice, although the first time was after the car wash and the belt may of been wet.

I've checked the 24 mm belt bolt it's not loose, the belt looks just fine.

I replaced my fan belt about three weeks ago, did not have all the original washers but had the recommended 1/2" play-deflection so I don't think it was on too tight.

I have not check the charging system, I have to look up how to do this yet.

My question is; when an alternator goes does it make this straining electrical motor noise?

I've had alternators go on other cars, never made this kind of sound.

Could The bearings be bad as well as the brushes? What other bearings are there?

Can this alternator be rebuilt or do I need to purchase a $350 one from Pelican?

http://www.pelicanparts.com/catalog/shopcart/911M/POR_911M_ELchrg_pg1.htm#item0

I'm kind of cash poor right now, looking for ideas.

The noise just started, don't want to run it like this, came straight home once it started - getting worse and consistanly worse quickly.

[Big Ed]

I don't know, but here in OT the cause of your problem is President Bush.

[kach22i]

Originally posted by Big Ed
I don't know, but here in OT the cause of your problem is President Bush.

Crap, it's started.

I have put in a request for the thread to be moved, please feel free to answer in a responsible manner.

[tobster1911]

+1 It's bushes fault. Maybe brushes at that.....

I would take the belt off and spin it by hand. You should be able to feel/hear if the bearing is bad. Other than that, take it off and to Auto Zone or the like. They can test it for you.

Edit: They should be able to test for free.

[RANDY P]

Originally posted by Big Ed
I don't know, but here in OT the cause of your problem is President Bush.

But seriously. Running light on shims can cause other maladies - such as thrown belts. Get some shims - make sure you have 6, buy a bunch of spares.

Rip it apart, and go through the alternator. You might have fried a shaft bearing if the belt was run too tight prior.

rjp

[chibone_914]

Sounds like the bearing on the armature has started to fail. I'd get the alternator changed out as soon as possible. Worst case scenario, the bearing will overheat, self-destruct and throw the belt.

[kach22i]

Originally posted by tobster1911
I would take the belt off and spin it by hand. You should be able to feel/hear if the bearing is bad.

Thanks, this much I can do.

When I first took the 24 mm nut off it was beyond torque spec's in my opinion.

I had a long steel bar on the end of the factory tool to get it off. Maybe that's when the damage started even though I had it braced with the bar and using the torque wrench as a breaker bar to equal the forces.

I kept thinking that the picture in Wayne's 101 Projects book better not be reversed - it took that much effort.

[RANDY P]

It was probably overtightened in an attempt to get the belt to stop wobbling.

Shims are missing, that's what happens. That, and belt slippage.

rjp

[kach22i]

Originally posted by RANDY P
It was probably overtightened in an attempt to get the belt to stop wobbling.

Shims are missing, that's what happens. That, and belt slippage.

rjp

I'll get the shims in before getting the alternator replaced.

Maybe the shims will take care of the problem if your theory is right and I hope it is new shims might save me.

The belt may of stretched just enough these past few weeks to of caused these problems without damage to the bearings.

[widebody911]

If it turns out you do have a bum alternator, you might be able to get it rebuilt locally. I had one done at a shop here in town for $95 or so.

[bigchillcar]

in arkansas..a rebuild job will cost ya around $50-60. i'd do that before buying a new one..
ryan

[kach22i]

My buddy with the 1981 Ferrari 308 GTSi had a place in Dearborn do his alternator for under $100. Dealership only part he was told, $400-$600 he was first looking at, it was a while ago I can't remember the exact cost.

Thanks for the offeres and suggestions.

I just ordered the shims $1.15 each from the local Porsche dealership (3-5 days). My pelican orders take over two weeks, closer to three so I really have to plan ahead.

[kach22i]

UPDATE 06/10/06

I found out the hard way that my 1977 2.7L has a 23mm fan bolt nut not a 24mm nut!

The alternator spins fine, no bushing or bearing issues.

I had to use a little sticky stuff to help hold in place the outer shim washers. They kept slipping out of place and getting all bent up.

I have the battery on a charger right now, it sounded a little weak last week, plus the alternator charging light was on after the installation. I don't want to put the belt on too tight so before I assume the belt is lose I'm making sure the battery has a full charge, and it does need a charge accourding to the charging meter on the charger. The battery charger is a better way to fully charge the battery, not the alternator - or so I just read in another thread.

23mm fan bolt nut ................24mm will work but not for long.

Tool Note: If you see a set of those really short open end metric wrenches do yourself a favor a pick up a set. makes getting the battery out a breeze.

[Early_S_Man]

If your alternator still uses an external regulator ... the nut should be 22 mm.

Also, if the alternator warning lamp has been on ever since installing the new fan belt, you should have started troubleshooting then! Three weeks is long enough for little problems to grow into big ones!

[kach22i]

Originally posted by Early_S_Man
Also, if the alternator warning lamp has been on ever since installing the new fan belt

The light came on today, not three weeks ago. When I said latest installation I meant today not three weeks ago.

So we have:

22mm

23mm

24mm

Covering early and mid-year 911's.

Are there any others we shold know about?

[bigchillcar]

backing up warren, here..the nut on my '74 is a 22 mm. i keep a 22 mm wrench in my car's emergency tool box along with a spare belt.
ryan

[Early_S_Man]

The '81 and earlier pulley nuts are 22 mm.

The '82 and later ... and all replacement alternators with integrated reguators use a 24 mm nut.

There are no 23 mm 911 alternator nuts, in spite of Bentley's errors!!!