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Thread: Alternator toast?

  1. #1
    Newbie ninjazombiemaster's Avatar
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    Default Alternator toast?

    My car had been driving kind of weird, stalling a little, and the head and dash lights would flicker when driving. This got worse and worse, until it was borderline undrivable, difficult to start (today it didn't start, dead battery), and running headlights seemed to make it worse. Rock Auto has several Alternators between 50-60 amps for about $30+shipping less a core charge, should I choose to send one. I could be mistaken, but I'm most likely on the 40 amp stock alternator.

    Does a dying alternator fit the bill for all this? And does anyone have a specific recommendation on the new unit? I'm not paying $100+ for an MSA one, though if I'm not already converted, it is my understanding I'll either need to purchase a external to internal regulator conversion kit, or rewire it myself in order to prevent the car from not shutting off / dying slowly from a trickle.. though I'm sure there are plenty of threads on that already.
    1973 240z w/ ztherapy round top conversion.

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    The flickering sounds like my Pathfinder alt before it died. But you have an external regulator on yours. You might just need a new regulator, your alternator might be fine.

    And your stock 73 alternator should be either 50 or 60 amps, by the FSM specs. If you already have a 60 amp, then switching to internally regulated won't get you much, if all you need is a regulator.

    Not positive, but I think a bad regulator can drain your battery also.
    1976 280Z, with some minor modifications

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    Newbie ninjazombiemaster's Avatar
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    One extra note. If the car is running, my amp meter sits dead center. Running lights, etc, push it left like normal. Normally higher RPMs pushes it to the right. However, it won't move right past the center line at all. If I idle and rev my engine really high, it goes crazy and the meter flies all over its range.
    1973 240z w/ ztherapy round top conversion.

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    Auto stores can check both separately if you take them in.
    1976 280Z, with some minor modifications

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    Barn Find Daily Driver Captain_Zeros's Avatar
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    If the ammeter goes to the left of zero, you need a bigger alternator in my book. I've got a used 280zx alternator and it runs everything like a champ. "rewiring" to use an internally regulated alt is piss easy, it's literally unplugging a connector and jumping the correct wires to each other in the chassis harness (early cars like ours like to have a diode in there to make sure the engine turns off when you take the key out, about a dollar at the local radioshark) . The 280zx alternator conversion kit plug does the same thing and looks sexy doing it, but it's not strictly required for a functional setup.

    Edit: pictures of all my car's wiring modifications to run a 280zx alternator. The blue weatherproof connector on the white wire is just because it ripped out of the 6 pin harness connector and that was easier than trying to shove it back in.
    Click image for larger version. 

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    Last edited by Captain_Zeros; 07-12-2013 at 08:16 PM.

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    Newbie ninjazombiemaster's Avatar
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    Yeah. I was gonna have it checked this morning, and then the battery died.. hah. So now its stuck in my parking space until I can find/buy a huge extension cord, or get lucky and maybe it turns over enough to start.

    Edit: Ninja'd the ninja -
    Quote Originally Posted by Captain_Zeros View Post
    If the ammeter goes to the left of zero, you need a bigger alternator in my book. I've got a used 280zx alternator and it runs everything like a champ. "rewiring" to use an internally regulated alt is piss easy, it's literally unplugging a connector and jumping the correct wires to each other in the chassis harness (early cars like ours like to have a diode in there to make sure the engine turns off when you take the key out, about a dollar at the local radioshark) . The 280zx alternator conversion kit plug does the same thing and looks sexy doing it, but it's not strictly required for a functional setup.
    I agree. typically when driving it stayed positive, but idling or driving at low RPMs for extended periods with a lot of things going on pushed it in the negative. Its been a nuisance, which is why I'm going bigger with the repair.
    Last edited by ninjazombiemaster; 07-12-2013 at 08:19 PM.
    1973 240z w/ ztherapy round top conversion.

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    Registered User 71Nissan240Z's Avatar
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    Test the output voltage at the alternator before the regulator. That should tell you what needs to be repalced

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    Newbie ninjazombiemaster's Avatar
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    Sounds like the smartest course of action is to charge it somehow and try to test it. In the long term, I'd like a bigger alternator, but right now my focus is getting back on the road, so if that means a new regulator, then so be it. They run about the same price on RockAuto. I'll check on my setup after I get off work and make sure I even have an external regulator. I'll post a picture, too.
    1973 240z w/ ztherapy round top conversion.

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    Barn Find Daily Driver Captain_Zeros's Avatar
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    If you can't find a long enough extension cord, carry your battery inside and charge it near an outlet

    I would strongly suggest the 280ZX distributor, mechanical voltage regulation is pretty objectively terrible from a performance standpoint.
    1973 240Z w/ roundtop carbs, 280zx e12-80 distributor, 280zx alternator, late model Altima junkyard electric fans. 115 Blue Metallic & white side stripes.

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    Newbie ninjazombiemaster's Avatar
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    Quote Originally Posted by Captain_Zeros View Post
    If you can't find a long enough extension cord, carry your battery inside and charge it near an outlet

    I would strongly suggest the 280ZX distributor, mechanical voltage regulation is pretty objectively terrible from a performance standpoint.
    Perhaps long term. But this is my only vehicle and I need it back on the road yesterday. At least manually charging it should suffice for the weekend.
    1973 240z w/ ztherapy round top conversion.

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    Registered User 71Nissan240Z's Avatar
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    If u need a step by step to test the output voltage before the regulator I can provide that too.

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    Z geek at large FastWoman's Avatar
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    FAIW, running your battery down that far sucks much of the life out of it and can possibly kill it. You shouldn't try starting your car on a weak battery. Charge it first.
    My last three sports cars while I still owned all three:

    2001 BMW Z3 Roadster 3.0i soft/hard top (sold)
    1966 Ford Mustang Coupe (sold)
    1978 Datsun 280Z (enjoying very much )

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    Newbie ninjazombiemaster's Avatar
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    Solid advice.
    I've been charging it at night in my place and reinstalling the battery every morning. Gets me to work and back. I'll get it to the shop Monday and test it, then order the part. At least it still runs. Its really weird how the ammeter goes nuts when my RPMS get high. I took a video, but haven't had a chance to upload it.
    1973 240z w/ ztherapy round top conversion.

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    could be over charging.
    things will only bother you if you let them.

    82 280zxt 4 spd auto
    73 240z--lsd, cv axles
    short throw info

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    Wouldn't that be more likely to cause battery and accessory failure than a dead battery though?
    1973 240z w/ ztherapy round top conversion.

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    The 280zxt i had, went to work, at lunch it was completely dead. I charged the battery and took it in to check. Idling it showed good, until I revved it high, then it showed 17+ volts. While taking it over to the shop, all the dash lights went haywire.

    Check it before it does damage to the battery. I had an optima so it didn't do much harm to it.
    things will only bother you if you let them.

    82 280zxt 4 spd auto
    73 240z--lsd, cv axles
    short throw info

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    Registered User LeonV's Avatar
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    Dead voltage regulator or alternator...

    FSM has test procedures, BTW.
    2/74 260Z

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    Details of Alternator upgrade & elimination of voltage regulator. Please note for the '73 you'll need a different jumper setup so that the fuel pump relay isn't always powered up.

    Dave's 1972 Datsun 240z: Alternator Upgrade
    Dave
    Windy City Z Club (Chicago)
    1972 240z, restoration in progress
    http://jarvas240z.blogspot.com

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    Thanks guys. It runs well enough to get it to the shop tomorrow, I'll give it all a try.
    1973 240z w/ ztherapy round top conversion.

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    Newbie ninjazombiemaster's Avatar
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    Just wanted to close this up. I tested the systems and determined it was the alternator. I was able to find an Ultima brand alternator locally, and put it in the same day. It did not fit initially.. I had to shave of a bit of metal to get it mounted. Just a warning to anyone purchasing that brand.

    I spent a little extra to get it local, but overall the cost of the repair was under $40.

    Other than the size issue, it went smooth and was a nice reminder of how easy these cars are to work on...

    For the time being, I am staying on an externally regulated system. With the new alternator, the electronics run better than they ever have since I bought it a year ago.. and the engine is actually louder! Makes me wonder if the weak alternator was actually shortchanging my ignition system.

    Either way, its running good again. Thanks for the help.
    1973 240z w/ ztherapy round top conversion.

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