Voltage spikes to 17 volts

[GettinPaper]

I just replaced the alternator, the one before couldn't keep it's charge now I replaced it. It holds 14 volts for like 3minutes when I first start it and then spikes to 17 and I hear my battery sizzling. I am thinking its the alternator but it tests fine at oriellys.. This is the 3rd alternator from them, first two couldn't hold charge now it's this?? What could cause this randomly?? Any help is appreciated

 

[RamenPride]

Bad voltage regulator..... Although you may be on your 3rd one, it happens with remanufactured alternators.

 

[turbobird14]

Bad voltage regulator..... Although you may be on your 3rd one, it happens with remanufactured alternators.

+1 I went thru 4 Duracrap alternators that all "tested" good. The problem is the testers the big box auto part stores use dont test the regulated output they just test for output alone. I would go with a used OEM alternator tested good over another one from autozone, orileys ect... again.

 

[GettinPaper]

Today after work I'm going to get my money back and buying an oem alternator

 

[greekgodchaos]

IMOE (own experience) I had this problem as well, Voltage regular failed and shot up to 19v. So I ended up getting a replacement from O'Reilly's, then that wasn't fixing it, so I exchanged it, but the second time I made a heat shield to protect it from the heat coming off the downpipe. After that, not one issue. People really tend to overlook the heat factor with these alternators, shield it and it will last like it is supposed to. 10,000mi later and its still perfect.

For those who may want to make a shield for their ALT, I used (IIRC) 3/16 thick steel, bent to avoid hitting the ALT, polished on the hot side, and sprayed with black ceramic header paint on the other to dissipate the heat, and 2 holes (1 top and 1 bottom, using existing OEM bolts). After a 30 minute highway drive @ 70mph, you can touch the black side for as long as you want without worry of getting burnt. Cooler = longer life. Its true for everything! Ill try to get a picture up sometime today if anyone wants me to.