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Electrical: Engine Starting, Charging
had the hole opened sufficently. Then I threaded the insulation over the new
brushes' pigtails. Then I prepared and tinned the wire ends (new brushes) and
tack-soldered on a 2' long piece of fine wire to use as a leader. Then I threaded the
spring over the pigtail. Then I stuck the end of the leader through the narrow hole,
from the brush side, and used it to pull the pigtail through. Once I pulled enough
through, I carefully (and gently) crimped the neck with cutters and then soldered
the pigtail. I bent it over and solder about 1/8" down the outside and then cut off
the excess. (You must pull enough through so that the pigtail will hold the brush
properly in the holder but fully extended.) Before installing the VR assembly, I
cleaned the internal contacts with a pencil eraser as well as cleaning the contact in
the alternator. I also cleaned and shined up the screw ground and mating surface
on the alternator case.
Alternator Regulator/Brush Reliability. [Inquiry] Is it wise to preventatively
change out a 10 yrs old voltage regulator now?
[Response: Gary DeFrancesco] The regulators themselves are fairly robust. It is the
attached carbon brushes that wear out. If let go too far, the bushes become
ineffective and the alternator stops charging eventually. I would pull the
regulator/brush assembly out and have a look at it. If the brushes are less than
about 3/16", I would go ahead and replace the assembly. An aftermarket assembly
costs about $20. A Bosch unit runs about $50. I have installed both in my 2 745Ts
this year. So far both are working fine. My gut feel is the Bosch assembly is going
to last longer, but time will tell. I know there are those who say the brushes can
be replaced and the regulator reused. If you have the tools and want to spend the
time, go ahead. However, I do not know how much longer the electronics in the
regulator will last. With all the heat under the hood, the electronics will eventually
fail. Will they last through a second set of brushes, I don't know. So I just
bypassed the question and put in totally new assemblies. Lets face it, $50 in the
scheme of things is not a lot of money. Especially when one considers the time
involved to solder in new brushes, the cost of the brushes (I know, they're cheap),
and the cost of a big soldering iron (if you don't have one). [Response: JohnB]
Only if you can't use a soldering gun and wire snips...costs about $10 or less for a
brush kit. Prophylactically change out the brushes at 140K miles. Note that some
folks have found that aftermarket regulators can cause poor voltage regulation and
driveability problems: see
Regulator
. Part numbers: 1988-1991 740 with Bosch 80 amp: Bosch regulator
1197-311-028 .
[Editor] For an older alternator, merely changing the brushes may not help much.
You should rebuild it with new bearings and turn the commutator.
If you have flickering instrument panel warning lamps, see
Flickering: Bad Alternator Brushes
Nippon Denso Alternator:
Brush
and
file:///C|/Users/Steve/Documents/Volvo%20FAQ%20Updated/ElectricalStarting.html[01/13/14 10:02:47 PM]
Unexplained Driveability Problems: Bad Voltage
for a solution.
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