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Registered
Join Date: Aug 2007
Posts: 1
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Voltage Drops on Radiator Cooling Fan Start
When the radiator cooling fan kicks in after idling in traffic for a while, the voltage hits the deck for a moment - the radio goes off, the engine hesitates, the tacho drops - then the voltage comes back up as suddenly as it went down, the tacho leaps, and then everything settles down.
Is this a sign of problems with the fan, the alternator, or what? Thanks guys!
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Red 1988 944S |
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08-22-2007, 02:09 AM
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Join Date: Jul 2007
Location: Slovenia
Posts: 73
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alternator brushes maybe.
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08-22-2007, 05:04 AM
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Join Date: Jan 2007
Location: New Hope, PA
Posts: 53
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I'm thinking the battery is a possibility - if its weak (which also could be a result of what Voith said) you will see that - when working properly, it makes a good load sync.
Try checking your voltage with the engine off, and then with it running, and then with it tached up to around 2000. You should see 12.something off, and hopefully high 14s when on as well as when tached up. |
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08-22-2007, 05:34 AM
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Join Date: Jun 2003
Location: Phoenix, AZ
Posts: 1,327
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alternator/voltage regulator/harness.
hi 14's will overcharge the batt, need upper 13's - lo 14's, fans/ac on. 12.5-6 overnite/off
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87 951, K27/6, Almond Beige, 17" Turbotwist 87 944S, alpine white, 5sp died a violent death 84 944, silver/brown, auto, gone but not forgotten "may the force be with you" |
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08-22-2007, 10:18 AM
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Join Date: Jan 2007
Location: New Hope, PA
Posts: 53
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Yeah...sorry about that. I did mean high 13s. 13.6 is what was on the last regulator I replaced.
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08-22-2007, 11:46 AM
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Join Date: Jun 2003
Location: Phoenix, AZ
Posts: 1,327
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i just did all the above.
had fluctuating voltage, big jump when the fans came on and did a new alt and batt harness, which was green like a swamp. when i pulled the vr out of the old alt, the brushes were less tha a 1/16th". now voltage is a needle width over 14 on start and runs just under 14 with fans/ac/lights. there's a calibration screw on the side of the vm in the cluster to get gage to read what dvm shows. good luck
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87 951, K27/6, Almond Beige, 17" Turbotwist 87 944S, alpine white, 5sp died a violent death 84 944, silver/brown, auto, gone but not forgotten "may the force be with you" |
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08-22-2007, 12:16 PM
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