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DonziDave
04-27-2006, 07:59 PM
Boat is '86 18C with stock Merc 350 SBC. Ignition is Merc T-Bolt IV and alternator is the original Motorola with the rear mounted transitorized voltage regulator. New battery, belt tight, connections good.

Problem: From idle to about 3000 rpm's the "low volt" light glows slightly. Above 3000 rpm's the light will go out. The volt meter stays constant at around 13.5 volts. No accessories (load) running. At night when I turn on the running lights and dash lights the "low volt" light will glow slightly at all rpm's.

Time to replace a 20 year old alternator or is there a fix? If replacement time, have it rebuilt or buy a new one? If replacing, who has a good source (cheapest)?

Thanks - Dave :confused:

MOP
04-27-2006, 09:23 PM
Boat is '86 18C with stock Merc 350 SBC. Ignition is Merc T-Bolt IV and alternator is the original Motorola with the rear mounted transitorized voltage regulator. New battery, belt tight, connections good.
Problem: From idle to about 3000 rpm's the "low volt" light glows slightly. Above 3000 rpm's the light will go out. The volt meter stays constant at around 13.5 volts. No accessories (load) running. At night when I turn on the running lights and dash lights the "low volt" light will glow slightly at all rpm's.
Time to replace a 20 year old alternator or is there a fix? If replacement time, have it rebuilt or buy a new one? If replacing, who has a good source (cheapest)?
Thanks - Dave :confused:

It sounds like the brushes are tired but after 20 years it is time to overhaul or replace. You can find decent deals on Ebay.

mrfixxall
04-27-2006, 09:55 PM
its got a bad diode in the regulator...or what mop said