Guest Norman Rogers Posted July 11, 2008 Share Posted July 11, 2008 OK, the alternator went on my '79 280zx. The symptoms were: All idiots light turned on (including the one I really didn't notice on the dashboard voltmeter). And, it cranked REALLY slowly when I started it to return home. OK, new alternator (bit bigger than the original -- pain to get it mounted, had to take off the bracket that was mounted to the engine block to get it up there). Car now charges -- except: Car died after driving 40 miles, wouldn't crank. Called AAA. Tried cranking it again -- it started, Whew! (I was on a first date and we were going to see a Cole Porter review). Got to the theatre. Called AAA during intermission and prevailed upon nice gal to put the service call in about 20 minutes before expected end of show (I didn't want to hazard driving home with lights on if car wasn't charging). Wrecker came and I bribed the guy to drop gal off at her car before bringing me home. OK, worked on car. Noticed that I had let the belt slip off the water pump/fan pulley when I installed new alternator. MY BAD! Fixed belt (belts were kinda new -- replaced with water pump two years ago). Car charges again! YEAHHH! Uh-oh -- noticed that red light in voltmeter stays on (other idiot lights off this time), and voltmeter doesn't get out of yellow. More checking. Noticed that wires to alternator were loose. MY BAD! I mentioned that it was a pain to get this new alternator mounted. But that's no excuse. Tighten all wires. Now voltmeter will show about 14 volts, SOMETIMES, and about 12 other times. Idiot light in voltmeter now extinguished. Took car from Greenwich to Paramas to test (and buy cigars at J&R). Runs great (I also fixed a bad vacuum hose). But voltmeter never got beyond yello (12 volts or so). And voltage would drop into yellow when I put the lights and A/C blower on. But, no performance problems. Car would crank properly and restart at will. And so, my questions are: What shold the voltmeter read at speed if the system is working properly and the battery is fully charged? Should the voltmeter stay in yellow with accessories turned on? What should I be looking at/doing? Thanks. Quote Link to comment Share on other sites More sharing options...
roger.svoboda Posted July 12, 2008 Share Posted July 12, 2008 go to harbor freight and buy a vom for like 15 bucks and then see what the alternator is really putting out. Should be 14 volts. If you are only showing 12 then you have a problem. I'd go to a battery place. Have the battery load tested and test the charging system. If you find out things aren't really working right you may have to get another alternator. Just because something is new doesn't guarantee that it is working as I sadly found out when I was sixteen and tuning up my 49 ford. New points car wouldn't start. Dad said how do you know the points are good? cause they are new says the kid. My dad said okay but how do you know they are good. On close examination found out the points were bad. lesson learned young. Also if you got a new alternator why couldn't you get one that fit? Quote Link to comment Share on other sites More sharing options...
Guest Norman Rogers Posted July 13, 2008 Share Posted July 13, 2008 Thanks Roger, But I did put a VOM across the battery and it shows 12v at rest, 14 or so (it's an analog meter) at 2000rpm (when first started) -- and with no accessories turned on. If I put on the lights and A/C and radio, we're down to 11.5v at 2000 rpm And, after about ten minutes, we're down to about 12.2v without accessories at 2000rpm. I want to know if these are normal readings. I'm concerned that the battery won't be charging with the lights on. Thanks. Quote Link to comment Share on other sites More sharing options...
280zx 2by2 Posted July 13, 2008 Share Posted July 13, 2008 are you sure the alternator you got dosent have a lower charge rate? cause the correct 14v out put from start could just be the car warming up with a higher rpm and when it cools your rpm drops and your voltage drops... i could be wrong and i probly am i dont realy understand elecretiocity... Quote Link to comment Share on other sites More sharing options...
woldson Posted July 13, 2008 Share Posted July 13, 2008 Excuse me for butting in. I found that some of the local battery/parts stores have some pretty good gear to help. Your problem may be more extensive but it is a good start. Quote Link to comment Share on other sites More sharing options...
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