New Alternator accompanied by Check Gauges Light

[Jon7I2]

So, I threw in a new alternator the other day from afterthoughts auto, and now my check gauges light comes on and off. I am not low on fuel, nor is any other gauge behaving abnormally. It will only come on when I am sitting in traffic or in a general stop and go pattern, when I am on an open road its fine. The only thing I can think is that the bolt in the rear of the alternator (where the ground wire attaches w/ a nut on the end) will not tighten completely in the alternator. The bolt will thread in good and hand tighten, but after 4 or 5 rotations w/ the wrench it just keeps spinning. It almost feels like it’s stripped, but it’s brand new and it still is more than hand tight (like I cannot spin it out by my hand at this point). Also, I don’t think this bolt has to be torqued town to some outrageous degree as long as it is snug seems like it should be fine, right? Or am I wrong here? Or did I just get a bad alternator here? Any advice or help would really be great, this stupid little problem is really driving me crazy!

[ls1alltheway]

is the voltage dropping?

[Jon7I2]

no, all the gauges read absolutely fine.

[0rion]

Yeah, have the alternator tested. Bolt sounds stripped to me. Is there any slop in the wire at all? If so it may be making partial contact. I forget if that's a bolt on the back of the alternator or a stud with a nut. If it's a bolt get a shorter bolt and if it's a stud with a nut put some washers on before putting the wire or nut on.

[ls1alltheway]

the bolt on the back of the alt is i believe a ground for the voltage regulator. and trust me they are known for stripping out very easily. if it's the little green colored screw it's just a body ground for the alt housing (to the body or frame). that should not cause that big of an issue. but the ground for the regulator will cause intermitent problems. i.e at idle or low rpm.

[Jon7I2]

how could i get the alternator tested? would u have to bring it somewhere?

[0rion]

Yeah, you'll have to pull it and take to a part store. Most parts stores will test it for free.

[Jon7I2]

shit so it probably is that bolt then. Damn, that makes sense too. I mean wen the alt. pulley is spinning (not at low rpm's, the bolt is completely contacting and sending electrical signal due to the vibration) but wen im at low rpm's the pulley is not spinning as much and some contact may be lost. That makes sense right? But i mean the bolt isn't exactly lose in the back of the alt, like i said its beyond hand loosening, so does it need to be really wrenched down good or would it b ok the way it is, so the problem may be elsewhere.

[0rion]

If you can't move the wire behind the nut I'd say that's probably good. It's free to check it out so I would probably at least check it to make sure everything is good back there. I would also double verify the part number to make sure they gave you the right one.