Re: Alternator problem?

[drew <drew@dyermaker.cs.uoguelph.ca>]

It's been my experience that the symptoms you describe (without a dimly
glowing or lit alternator warning light) are because of worn brushes or
bad regulator.  I did have one alternator from a TD that was gummed up
with soot and oil, and the brushes were stuck in their sleeves.  A quick
shot with solvent and they were free again.

Given the voltages you're seeing at the battery, it's unlikely to be a
grounding problem (now, on the older 1.6's that used rubber mounts for the
alternator and had a grounding strap, this is pretty indicative of what
you would see when the grounding strap broke.)

It would be worth trying the new regulator/brush assembly to see if it
solves the problem.  You may wish to use a bit of emory to shine up the
slip rings while you have the brushes out.  It's easy to do this by
removing the belt and turning the alternator pulley by hand while you hold
a piece of fine sandpaper or emory on the slip rings.  Electrical contact
cleaner can help to remove carbon dust as well.  At the same time, check
for corrosion on the contact point for the volatge regulator: there's a
little copper tang inside the alternator that presses against the contact
on the regulator/brush assembly.  Both the tang and the contact should be
clean and shiny.  I've seen aftermarket (ie not Bosch) regulators that had
contact points that seemed to corrode (or rust) very quickly.

HTH,

Drew


On Thu, 4 Jan 2001, Ewan Hopkins wrote:

> On my way home last night I noticed that the lights were slowly getting 
> dimmer and the wipers were very slow - had to switch everything off and 
> drive 20 miles, in the dark,  on sidelights (not to be recommended!) - only 
> just made it home before the battery ran out. The battery warning light 
> didn't show at any point. Gave it an hour on the charger and it started 
> fine. Stopped it and metered the battery: a bit below 12v - to be expected 
> on a partial recharge. Started the engine and metered again - 12.2V, dipping 
> to under 12V when revved.  It appears to be giving a partial charge - 
> leaving it to idle with all electrics switched off (load=fuel 
> pumps+ignition), the voltage crept up by 0.5V after a few minutes.  Is this 
> likely to be a faulty regulator in the alternator/worn brushes or something 
> else - blown diodes in the alternator / faulty voltage stabiliser / 
> something else.  I've got a new regulator but haven't tried it yet. Any 
> ideas?
> 
> TIA,
> 
> Ewan Hopkins
> '85 Storm 2.0
> '86 GT 1.8
> _________________________________________________________________________
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Drew MacPherson, Network Analyst, University of Guelph

drew@dyermaker.cs.uoguelph.ca           |  visit the Massey-Harris page:
http://dyermaker.cs.uoguelph.ca/~drew   |  http://m-h.cs.uoguelph.ca


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