Decided to check the alternator (model number 1 5-6-7 ACR ...yes that's really
how it reads) on my TR6 as a result of the thread last week. And also because I
wasn't seeing the needle on my ammeter on the plus side of the gage when I
thought it should be (under load).
I did some of Dan Master's tests. e.g. Ran the engine at 1500 rpm or better,
turned on high beams, heater motor, radio, etc, and measured the voltage at the
battery. I got 12 volts on my voltmeter...it should be 14 - 15 volts according
to Dan.
Put a voltmeter on the plus lead of the coil, and to see what the voltage read
with all the above electrical devices turned on. According to Dan If it's the
alternator that's the problem, you should see a fairly large voltage drop. I
didn't see a large drop...the voltmeter still read 12 volts.
I checked the battery with the engine off and it was right at 12 volts. The
battery cranks the engine with pretty good zip so I think it's OK.
I checked for voltage on the small brown wire. According to Dan there should be
12 volts on this wire at all times, key on or off and there was 12 volts.
Decided to pull the alternator apart after reading Dan's article on Alternator
Diagnosis and Repair. During the checks listed in the article I discovered that
the slip rings were real dirty (carbon) and the "center" ring didn't give a good
solid contact when checking continuity with the ohm meter. I wasn't quite ready
to delve into unsoldering the stator leads to do the suggested tests so I
cleaned the slip rings and the brushes and put it all back together and back on
the engine.
Repeating the same tests above gave a voltmeter reading of 13 volts at the
battery (with engine running) and at the plus side of the coil. That was with
all electrical devices turned on and creating a load. The needle on the ammeter
did go into the plus side to show that the alternator was putting out more amps
than before.
I'm still wondering though why I'm not getting the 13.6 to 14.4 that I was
expecting to get? Although I'm using a small/cheap multimeter (and it's not
digital) it is usually pretty close. I also got similar values using my trusty
alternator/battery checker with the 6 light readout that shows output in 1/2
volt increments. I guess I should be happy that the alternator is at least
keeping the battery charged but I'm concerned that it's headed for future
problems. I'm thinking about replacing the regulator or the diode pack (after
some more testing) in the existing alternator since that would be a relatively
cheap fix compared to buying another Lucas alternator.
I also looked into the GM units. Looked for the model #7127 that Dan suggested
but that seems to be a remanufacturer's number and the parts stores (including
NAPA) couldn't seem to cross reference it to any thing they had. DAN: Do you
have any other numbers or info. on those units?
If I go that way I'll have to convert my five wire/two connector wiring to the
three wire/single connector. Which I think I can handle since Dan so aptly
describes how to do it.
Dan are you out there? Or anyone else that can help? Any suggestions on
getting the alternator to put out full voltage?
Thanks
Bud 71TR6 CC57365
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