Old 07-11-2019, 12:06 PM
nodwyer's Avatar
nodwyer nodwyer is offline
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Join Date: Sep 2007
Location: Oxford, Mi.
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Default 66 gto charging issues

Hi all, i recently had a dead battery so went through the obvious fixes. Car wouldnt run when taking off the neg. cable from battery.
Replaced alternator with a powermaster 60 amp i believe.
Still wouldnt run when taking off the cable. Replaced voltage regulator with a delco brand. Same issue. Seems to charge the battery, im getting 12.5 volts but no more when its running. Turned on the headlights and dropped to 11.9 volts but seems okay, not getting anything more to the battery than 12.5 volts even when revving. What am i missing. Neil O
Old 07-11-2019, 04:48 PM
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johnta1 johnta1 is online now
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Why taking off the battery cable (when running?)?

Any wiring changes?

I'd check all connections for a good contact.
The battery ground needs to be connect to complete the circuit.
Also check the other ground wires, frame to engine, etc.

Were the alternators new or ones laying around?

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Old 07-11-2019, 05:58 PM
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nodwyer nodwyer is offline
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Thanks for the reply I thought if you disconnect the battery while running and it quit then there is a problem with the charging system. Not right? And the alternator is brand new
Old 07-11-2019, 08:51 PM
Goatracer1 Goatracer1 is offline
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That's a good way to blow the diodes in the alt.
Old 07-12-2019, 06:09 AM
Geoff Geoff is offline
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Location: Australia
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I am assuming your testing was done with a battery that was fully charged.

From the voltages provided, the charging system is not charging. Could be alt, regulator or wiring.

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