Auto Electrics / Alternator

[j1autotech]

Hi guys,

I think the old alternator is on it's way out, bearings do not sound happy at all and Batt. loosing charge.

Anyone know of a good Auto Electricians in J/burg, Randburg area ???

Looking either for a change over or a rebuilt job.

I think it's an old email type in the Fairmont GT.

Cheers

J1

[72XYGT]

J1,
If you get another dont get rid of the original. If possible try a rebuild.
Daan

[zahistorics]

Yep, I thought rebuild too. Both to keep originality, and because there's not a lot to go wrong on an altenator. Easy to DIY.

Bearings are cheap - pull them out and take them down to a bearing supplier. About 95% or more of all ball race bearings are stock size items - no need to buy them from a specialist

Most likely charging problem:
Belt slippage! Made worse if the bearings are gone causing lots of friction.

Most likely electrical problems (aside from broken wires and corroded connectors) are in order:

1. Worn slip ring brushes - again usually cheap (assuming the are available) and easy to replace

2. Broken regulator - depends on altenator - may not be in the altenator at all.

3. Blown diodes - easily tested with a multimeter - so check first before chasing regulator problems.

[j1autotech]

Thanks guys.

I checked the belt the other day for tension as it was replaced last month with the others due to there age.
The alternator was making noise at 2850rpm for the last couple of weeks, I thought this may have been just a weird harmonic but I think it may have been the bearings on there way out. The other day when the battery went totally flat, I found that the main lead to battery had basically melted off the back of the alternator. It had been attached with an electrical twin screw connector as the lug on the output had either broken or coroded away. I cut the old connector off and stripped the main output wire and used a new connector of the same type to get me going for a couple of days till the job could be done properly. After starting the car and running it for a while to see if the charge in the battery would build, the alternator became very very hot. When I mean hot, hotter than the exhaust manifold. So I'm guessing that the bearings are most likey knackered.

J1

[72XYGT]

Better not running the alternator like that as it could seize up some bearings resulting in actual wear of the bearing housings. When in that condition the alternator is basically worthless and must be completely replaced.

Daan

[zahistorics]

If you do (or have) run the bearing housings you can easily fix that with a bit of epoxy.

1. Clean the housing well.

2. Apply a thin film of oil to the outside of the ball race. This is a release agent so it will come apart in the future.

3. Mix up a little bit of epoxy and apply a little bit to the bearing housing. Just enough to fill the gap. Put it in a bead around the top of the recess only, not all the way down.

4. Push the bearing into the housing. Doing this will spread the epoxy all the way down the housing.

5. Do the other bearing if necessary.

6. Immediatly assemble the altenator - the altenator shaft will align the bearings - turn the shaft a few times.

7. Leave it for the epoxy to cure.

This also works treat for two stoke engine main bearings. I rescued quite a few Yamahas using this trick.

Years ago we used to use Pratley White Epoxy, it was just the right consitency. Don't know if you can get it in ZA now.

Don't use quick set epoxy because it cures too fast.

[72XYGT]

Amazing, John, you remind me of one of those "blou draad en tang" guys. With all the various goodies on the market today you can even repair holes in a block!
I like this tip. Perhaps we should start a section on tips. What you think Tiaan?

Cheers,
Daan

[zahistorics]

I might live in England, but I definately learned in the 'Boer maak 'n plan' school.

[72XYGT]

I might live in England, but I definately learned in the 'Boer maak 'n plan' school.

John, then you should know the other saying; "n Plan is n boerdery!"