Date: Mon, 22 Aug 2011 19:32:34 -0400
Reply-To: Dennis Haynes <d23haynes57@HOTMAIL.COM>
Sender: Vanagon Mailing List <vanagon@gerry.vanagon.com>
From: Dennis Haynes <d23haynes57@HOTMAIL.COM>
Subject: Re: Alternator Brushes Wore Out Pretty Darn Quick
In-Reply-To: <4E52D6CF.3070000@gmail.com>
Content-Type: text/plain; charset="US-ASCII"
An easy check of the alternator rear bearing is to remove or at least loosen
the belt, then using finger pressure on the fan at 3 and 9 o'clock try to
rock it. It the fan can wobble or you hear any clunks the rear bearing or
nylon insert is a goner. I have seen some where the rotor has actually
contacted the stator and made some nice cuts.
Dennis
-----Original Message-----
From: Rocket J Squirrel [mailto:camping.elliott@gmail.com]
Sent: Monday, August 22, 2011 6:23 PM
To: Dennis Haynes
Cc: vanagon@GERRY.VANAGON.COM
Subject: Re: Alternator Brushes Wore Out Pretty Darn Quick
Dennis: Thanks for the explanation and visualizations of what's going on
back there. In my case, the alternator doesn't have to work much harder to
charge up my big aux battery as the 12 volt > 12 volt deep cycle charger is
current-limited to 7.5 amps. But the mechanical issues you describe . . .
would squealing -- sounding like a belt -- or "whooping"
sounds when the engine is started maybe result from a worn alternator?
ALL: Recommendations on how to deal with an alternator that maybe needs
servicing? Who does such things? Take it to the FLAPS or do we have some
special vendor here whose rebuilt Bosch alternators are better than gold?
AND DENNIS WRITES: "Having the bearings crash also means no water pump so
you are now stranded. Also since the failure will usually occur on the
highway you have to consider the effect of the engine overheating by the
time you realized what is happening."
Thanks a lot, Dennis. Already I am self-described and diagnosed here as a
worrywart. This just gives me even more to fret about.
--
Jack "Rocket j Squirrel" Elliott
Bend, Ore.
1984 Westfalia. A poor but proud people.
1971 "Ladybug"-brand utility trailer ca. 1972 from a defunct company in San
Clemente, Calif., now repurposed as The Westrailia.
Sent from my kitchen.
On 08/22/2011 03:04 PM, Dennis Haynes wrote:
> Yes there are many grades, materials, etc. used for motor brushes. In
> addition there is also the type of use. The voltage regulator controls
> alternator output by varying the magnetic field (current) of the rotor
> as it spins in the stator. Since you are now using the alternator to
> charge additional batteries it has to regularly work a lot harder.
> Using the adjustable regulator to raise the set voltage makes things
> even worse. To add to the dilemma the original brushes are somewhat
> hard and they also wear the slip rings on the rotor. New brushes will
> quickly get chewed up as they will try to go into those grooves. Also
> at that mileage the rear bearing or the insert that holds it is most
> likely shot allowing the rear of the rotor to move around. As the
> rotor loses center the alternator loses efficiency and again more current
is passed in the rotor to compensate.
>
> The main point is that worn brushes are also an indication that it is
> time for the alternator to be fully serviced. Having the bearings
> crash also means no water pump so you are now stranded. Also since the
> failure will usually occur on the highway you have to consider the
> effect of the engine overheating by the time you realized what is
happening.
>
> Dennis
>
>
> -----Original Message-----
> From: Vanagon Mailing List [mailto:vanagon@gerry.vanagon.com] On
> Behalf Of Rocket J Squirrel
> Sent: Monday, August 22, 2011 5:29 PM
> To: vanagon@GERRY.VANAGON.COM
> Subject: Alternator Brushes Wore Out Pretty Darn Quick
>
> Buried in my post from yesterday (about an intermittent charging
> issue) is a question about the wore-out brushes on the voltage
> regulator. The reg/brushes can't have more than 20,000 miles but were
> worn to nubbins, less than 1/8'' long.
>
> Fortunately I had my old voltage regulator which probably has 70,000
> miles on it and its brushes were much longer so I swapped it in and
> the charging system is working fine.
>
> What can cause brushes to wear quickly?
>
> Do different brands of brushes wear differently? (The ones that wore
> out quickly were on an aftermarket adjustable voltage regulator, my
> old one with the still-long brushes is a factory type).
>
> Could something have happened within the alternator to speed brush
wearing?
>
> --
> Jack "Rocket j Squirrel" Elliott
> Bend, Ore.
> 1984 Westfalia. A poor but proud people.
> 1971 "Ladybug"-brand utility trailer ca. 1972 from a defunct company
> in San Clemente, Calif., now repurposed as The Westrailia.
>
> Sent from my kitchen.
>