My sons wagon has started acting up, this time with the alternator. Everything was fine until he hit the headlights and about 10 miles later leaves us on the side of the road. Called the better half for a jump start and everything is fine for another 10 miles. Now if it wasn't charging the voltmeter would slowly drop down however the observed drop was very rapid, 9.5 miles and it dropped to around 8 volts slowing the fuel pump and leaving us running on 2 cyls (B27)so another jump start at exactly 10 miles driven. We did this process 3 times to cover 32 miles and all the while the alternator appeared to be charging then dropped off like a rock and left us coasting on 1 1/2 cyls.

Sound like a regulator or something gone thermal? I can hit the defog, heater motor headlight and pull almost 40 amps from the alternator, pull the battery cable off and it keeps running however that magic 10 miles or 10 minutes and it drops off in output or so it seems however sitting in the driveway with everything running I gave up on the test after 45 minutes at elevated idle, problem only happens while going down the road. Mind you this engine suffered a direct hit from a drunk semi driver almost 2 years ago squshing the cars hood into a protuding chassis bolt after knocking the engine/trans under the vehicle so after all that why would the alternator now protest?

Ideas? Thoughts? Or am I just plain nuts?

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