I just replaced my alternator the day before I went to summit point. The whole way driving there and at idle my voltage is a rock solid 14V. When I was on the track on the main straight (at 5-7grand) I noticed that my voltage would swing pretty rapidly between 14 and ~16V. After I got off the track, and the entire drive home I once again had rock solid 14V. I’m assuming that since the alternator was changed that it is the cause of this voltage fluctuation but before I go return it (because it is working at cruising rpm) I wanted to see what you guys thought. Any thoughts?
Voltage fluctuations at high rpm
- Thread starter NJSHO
- Start date
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jelloslug
Digital
It sounds like a bad regulator. I had one that would do that and before long it would not put out over 13 volts.
Storm-Chaser
New Member
Two on the - "had the same thing".
First noted periods of 'brighter' headlights and some dash lights (most notably the clock) when the regulator would go into one of it's "high-fit" modes. The alternator didn't last a week - but did pass every at-the-auto-parts-store-test every time I went back with my "Lifetime Warranty" unit, until it physically failed. Hmmm.....
And for those of you that weren't aware....
Most alternator (re)manufacturers only fix what is bad/broke at the time they receive the core for rebuild. They [non-OEM remanufacturers] don't completely rebuild the alternator (hence how they undercut a Ford remanufactured unit which is completely overhauled). The unit is tested and (partially) disassembled. Those items that fail to pass their minimum-level tolerance tests are reworked or replaced, those that pass are simply put back into the rebuilt unit as is. This is why so many alternators and starters are either bad-out-of-the-box, or fail within a very short period of time.
First noted periods of 'brighter' headlights and some dash lights (most notably the clock) when the regulator would go into one of it's "high-fit" modes. The alternator didn't last a week - but did pass every at-the-auto-parts-store-test every time I went back with my "Lifetime Warranty" unit, until it physically failed. Hmmm.....
And for those of you that weren't aware....
Most alternator (re)manufacturers only fix what is bad/broke at the time they receive the core for rebuild. They [non-OEM remanufacturers] don't completely rebuild the alternator (hence how they undercut a Ford remanufactured unit which is completely overhauled). The unit is tested and (partially) disassembled. Those items that fail to pass their minimum-level tolerance tests are reworked or replaced, those that pass are simply put back into the rebuilt unit as is. This is why so many alternators and starters are either bad-out-of-the-box, or fail within a very short period of time.
jelloslug
Digital
Werd, I went through 4 NAPA "Gold" alternators before I had one that would work more that 2 weeks (and it only lasted a year). One of them had bad bearings right out of the box. I think the biggest problem with the "rebuilt" alternators is the factory ones last so long that every part is so close to failing one one part fails you are left with 15 other "almost broken" parts. The "rebuilder" only replaces the totally failed part and boom you have a 2 week old alternator crap out.Storm-Chaser said:
Smittysshoplus
New Member
I had that problem before the first one was fine for a long time and then out of no where my battery was making bad noises lol, went and got a brand new one and put it in and it worked great then the battery started making noises and I figured I would wait and then two days later nothing battery light came on and had to put another one in. Pain in the A$$ but, the brand new one was bad got it exchanged for free and the 2nd new one works just great so far. Good luck!!!
Well Im on my 3rd alternator the first 2 were the same manufacturer, and this one is different. Same problem is occuring. I want to check other things besides the alternator just as a sanity check. Could this be a grounding problem? I should also mentiont that my battery is in the trunk if that might bring up other things to check.
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Scrap the last post. I did some testing on the way home from work just after washing my car (might be a clue.)
1. Headlights off no voltage wiggle at any rpm any amt of throttle
2. Headlights on voltage wiggle
3. Headlights off, parking lights on. If im light on the throttle and just cruise up to 7000 rpm, there is no voltage wiggle. If Im at say 5500 and nail it i get the wiggle, but it does it slower than when I have all the headlights on.
My headlights are on harnesses.
1. Headlights off no voltage wiggle at any rpm any amt of throttle
2. Headlights on voltage wiggle
3. Headlights off, parking lights on. If im light on the throttle and just cruise up to 7000 rpm, there is no voltage wiggle. If Im at say 5500 and nail it i get the wiggle, but it does it slower than when I have all the headlights on.
My headlights are on harnesses.
HotRodKid
mmmmm ... turbo
the fix:
hit alternator with sledgehammer
take back to napa
...or is it only somedude that has that good of a warranty ? lol
hit alternator with sledgehammer
take back to napa
...or is it only somedude that has that good of a warranty ? lol
I finally got a new, not rebuilt, alternator and it fixed the problem. None of the alternator shops around here would even attempt to rebuild my old one. One guy described it as a "Pandora’s box," once you open them they never work right. I guess that explains why there are so many problems with rebuilt alternators for the sho.
edit: The new alternator was from a mom and pop store. Advanced just refunded my money since none of the brands they had worked right.
edit: The new alternator was from a mom and pop store. Advanced just refunded my money since none of the brands they had worked right.
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FWIW Advance Auto Palladium alternators can be had 100% new, the rebuilds are all new except for the case. Still I had one that only lasted 5 months before there were pieces clanking around in it. They still insisted that the need to test it. Locked up their testing machine though. 
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