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Registered
Join Date: Sep 2001
Location: Kerrville, Texas
Posts: 1,021
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Alternator Rebuild Frustration
I replaced the alternator last week and it looks like the rebuilt unit isn't working. This happened once before about 5 years ago. Anyone else have the same run of bad luck with rebuilt alternators?
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1987 911 Guards Red Targa, nearing 200,000 miles, lowered, 7's & 8's, 964 grind cams from John Dougherty, A.P.E. Mass Flow Sensor with chip to match, cat bypass, strut brace, dual out muffler. Will consider newer model in 8 years when I turn 75 and then maybe not. 2012 BMW 528i (wife's) 2007 Toyota FJ (rain and off road days) |
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06-22-2004, 01:49 PM
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Registered
Join Date: Dec 1999
Location: Los Angeles
Posts: 2,479
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weird. Battery's not roasted from the other alternator? My rebuilt one worked great.
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06-22-2004, 02:39 PM
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Join Date: Sep 2001
Location: Kerrville, Texas
Posts: 1,021
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What's also strange is the alternator light doesn't go on when I turn the key to the first position. I jumped started the engine and then disconnected the battery which caused the engine to die immediately. If the alternator was good I thought the engine would continue to run.
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1987 911 Guards Red Targa, nearing 200,000 miles, lowered, 7's & 8's, 964 grind cams from John Dougherty, A.P.E. Mass Flow Sensor with chip to match, cat bypass, strut brace, dual out muffler. Will consider newer model in 8 years when I turn 75 and then maybe not. 2012 BMW 528i (wife's) 2007 Toyota FJ (rain and off road days) |
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06-22-2004, 05:14 PM
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Who is John Galt?
Join Date: Jun 2003
Location: Knoxville, TN
Posts: 638
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You need a partially charged battery to excite the field in your alternator. Put a trickly charger on the battery overnight and try again. If the battery is totally dead, the alternator won't function.
You meant that you disconnected the jumper battery with the engine on, right? Don't ever disconnect the car's battery with the engine running. The battery plays an important part in clamping the voltage from the alternator. If you disconnect it with the engine running, you'll do some serious damage.
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'79 911sc Targa '02 slk230 kompressor '84 Tamiya Falcon A democracy cannot exist as a permanent form of government. It can only exist until the voters discover that they can vote themselves largesse from the public treasury. From that moment on, the majority always votes for the candidates promising the most benefits from the public treasury with the result that a democracy always collapses over loose fiscal policy, always followed by a dictatorship. The average age of the world's greatest civilizations has been 200 years. |
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06-22-2004, 06:21 PM
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Join Date: May 2000
Location: Los Alamos, NM, USA
Posts: 6,044
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If you disconnected the battery (should never do while the engine is running) or if it was bad you may have fried the diodes in the rebuilt alternator when you disconnected the jumper cables or the battery cable (which ever you did). Battery should be charged separately; it is bad practice to expect the alternator to charge a dead battery. Jim
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06-22-2004, 06:33 PM
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Registered
Join Date: Apr 2001
Location: Linn County, Oregon
Posts: 48,529
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I've never figured out why alternators needed electricity in order to make electricity...but it seems that is the case...
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"Now, to put a water-cooled engine in the rear and to have a radiator in the front, that's not very intelligent." -Ferry Porsche (PANO, Oct. '73) (I, Paul D. have loved this quote since 1973. It will remain as long as I post here.) |
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06-22-2004, 06:38 PM
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Registered
Join Date: May 2000
Location: Los Alamos, NM, USA
Posts: 6,044
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"Seed" magnetic field has to come from somewhere: either an electromagnet (field coils) powered by an external voltage source (like a battery) or from a permanent magnet. Jim
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06-22-2004, 06:46 PM
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Moderator
Join Date: Dec 2001
Posts: 9,569
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There are 50 threads in the archives that describe exactly this situation in detail.
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'66 911 #304065 Irischgruen ‘96 993 Carrera 2 Polarsilber '81 R65 Ex-'71 911 PCA C-Stock Club Racer #806 (Sold 5/15/13) Ex-'88 Carrera (Sold 3/29/02) Ex-'91 Carrera 2 Cabriolet (Sold 8/20/04) Ex-'89 944 Turbo S (Sold 8/21/20) |
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06-22-2004, 06:49 PM
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