1974 Porsche 911S 2.7 engine Alternator
09-21-2005, 10:41 AM
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1974 Porsche 911S 2.7 engine Alternator
1974 Porsche 911 S 2.7 engine
The red light (G) on the oil temp guage is on all the time. Belt is good.
The parts store show three part numbers for this car:
1) Bosch 55 AMP
2) SEV 55 Amp
3) SEV 70 Amp
Are all of these three interchangeable? Can a 70 amp be used instead of a 55 Amp?
Simple ways of checking if alternator and voltage reguator? I have a volt meter, ohm meter and clamp type amp meter.
The local parts store has no way of checking this alternator.
Do the voltage regulators and alternators fail much?
The red light (G) on the oil temp guage is on all the time. Belt is good.
The parts store show three part numbers for this car:
1) Bosch 55 AMP
2) SEV 55 Amp
3) SEV 70 Amp
Are all of these three interchangeable? Can a 70 amp be used instead of a 55 Amp?
Simple ways of checking if alternator and voltage reguator? I have a volt meter, ohm meter and clamp type amp meter.
The local parts store has no way of checking this alternator.
Do the voltage regulators and alternators fail much?
09-22-2005, 09:14 AM
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Update
It seems that a update was provided for this alternator. A Valeo 2541768 or A13N 281 50 Amp was updated from the Bosch stock unit. The Valeo has an internal voltage regulator. Some wiring changes have to be made.
The orginal style and the update version look very different.
The orginal style and the update version look very different.
09-23-2005, 02:05 AM
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Do a search, there are threads on alternators here. I just had the same problem (volt meter showing 12.5 volts at the battery at idle and 2,500 rpm, lights going from dim to bright), took my alternator out (it had already been updated to the internal regulator). I had it tested at an auto electric repair shop and it checked out fine. I had new brushes put in. I had a wire behind the alternator that had been spliced with a butt connector. I soldered that and used heat shrink tubing, cleaned all the grounds and connections, put a new belt on and it works great. The alternator is a pain to take out, I strongly suggest cleaning all the grounds and connections to the battery, making sure the battery is good. You could also try a new regulator since it just plugs in easily without taking the alternator out on your car.
Arne.
Arne.
09-23-2005, 08:03 AM
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I took out the alternator. It was the latest version using the update. None of the parts stores could help me with this. They had no clue, just reading part numbers on a screen. The old days, people used books with images.
I took the unit to an alternator / starter shop. The problem was a ground between the alternator and the internal regulator. He clean the contact and ran a test for 1/2 hour. Everything is working good. Charge me $30.00
It was a lot less than I expected. I was bracing myself for a $250 cost for a new unit.
I took the unit to an alternator / starter shop. The problem was a ground between the alternator and the internal regulator. He clean the contact and ran a test for 1/2 hour. Everything is working good. Charge me $30.00
It was a lot less than I expected. I was bracing myself for a $250 cost for a new unit.
