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View Full Version : Electrical: Alternatior/Voltage Regulator Problem 1963 Avanti conversion to 1988 Toyota Tercel Alternator



Stan.Gundry
07-07-2012, 10:32 PM
Several weeks ago I completed the conversion from the original Prestolite Alternator with external Voltage Regulator to the bolt-in 1988 Toyota Tercel Alternator with internal Voltage Regulator. I followed the instructions for the conversion carefully and even had my local old-timer mechanic confirm that I was wiring it right.

Every thing seemed fine from the get-go. It charged the battery for 3 or 4 minutes after starting and then the needle on the Ammeter settled right in the middle the dial. I have driven it 4 or 5 times and probably put at least 60 miles on the new set up.

It was fine, until today. When I started it up today to take my great grandson for a ride (yes, he appreciates the finer things of life like I do), the Ammeter showed a significant discharge, both with the ignition key on and with the car running, a discharge of about 10 amps if the Ammeter is to be believed. gunning the engine made no difference.

What is the likely problem? A bad Alternator/internal Voltage Regulator (purchased a rebuild from Rock Auto)? A short in my original wiring harness (I did take the precaution of installing a 60 amp fuse in the cable that goes from the Bat. terminal on the Alernator to the + terminal on the Ignition Switch)? Something else?

What tests can I do to find out what the problem is? Right now I am thinking I should have stuck with the old Prestolite, but the new setup seemed to promise more reliability.

G T Joe
07-08-2012, 10:21 AM
What is your chargeing voltage at idle ? are your connections tight? can you full field the toyota alternator? to see if it is the alternator or the reugulator is at falut? can you measure the amp output of the alternator? I have seen this coverstion before on some Studes and Avanti's and in my opinion more reliable than the presolite chargeing system, because prestolite alawys had problems back in the day bad quality control and poor workmenship, had 4 brand new prostlite altternators that were defective right off the shelf.

Hawklover
07-08-2012, 05:51 PM
Why did you seek to replace the oem units? Jon Myer sells brand new VR's that are a direct drop in.......and if you have access to a good honest elect repair shop, why change...or reinvent the wheel? I have a elect repair shop in business for about 50 yrs......you would not believe how he saved my arz so many times.....the 40 amp Presto he rebuilt for me...better than new! If interested in this shop.....contact me off list.
What is your chargeing voltage at idle ? are your connections tight? can you full field the toyota alternator? to see if it is the alternator or the reugulator is at falut? can you measure the amp output of the alternator? I have seen this coverstion before on some Studes and Avanti's and in my opinion more reliable than the presolite chargeing system, because prestolite alawys had problems back in the day bad quality control and poor workmenship, had 4 brand new prostlite altternators that were defective right off the shelf.

avanti larry
06-06-2013, 06:22 PM
What was the part number of this alternator-every one I sa was a 3 or 4 grove?

Studebakercenteroforegon
06-07-2013, 12:26 AM
I have been driving Studebakers with Prestolite alternators for over 40 years. Yes, I have had some rebuilt by a local rebuilder, but the result was always successful.