issues with my alternator

[Raceit]

I think my alternator is going out. Opinions?
In the morning when the engine is cold there doesn't seem to be any problems with voltage. During this time I can run my head lights, stereo, and amp.
Once it warms up I can't have it in drive and come to a full stop without the voltage gauge in the dash dipping down. But if I put it in netural or park the needle pops back up. All of that was with the head lights, stereo, and amp going.
As far as I know the alternator is factory with over 170K miles on the engine. I have a new (less then 4 months old) 900 cold cranking amp battery. Also, according to the temp gauge, the engine doesn't seem to get very hot. So I assume there isn't excesive heat in the engine compartment.
I was looking at the 130amp alternators from Mr.Alternator.com for $155. Is there any reason I shouldn't get it from there? Plus I couldn't find any on carparts.com, if somebody knows where, point me in the right direction. And if there are any good spare coupons floating around that would help too.
Thanks for letting me sit in the Doctors 'couch' and explain my problems. Or at least my Explorer's problems.

 

[Big Al]

Raceit,
I've got similar problems with my '94. Don't notice it related to the cold ,but my voltage gauge drops when I put on heavy draw accessories like the defogger or fog lights. However I'm still getting over 14 volts at the battery so the alternator is probably going but not shot. Battery is a few years old but of good quality. One sol'n is to strip it out and take it to a parts store to be bench tested. I'll also pick up the 130 amp vs something like a 175 amp . Prices at my local parts stores are pretty close to online places. You'll have to pay to ship the old one back to them since they all charge a core fee.

 

[mattadams]

funny you should mention that... mine was doing the same thing... I just replaced it last night, so far it seems to be working... I'm not sure if mine was temperature dependant because the only time I drove it was when it was cold and snowy out! but I drove it around fo ra while last night and it seemed to be getting enough juice... even turned on some fog lights and the voltage didn't drop lik ebefore. Before voltage was dropping almost to 8 amps and hte lights got so dim inside that I could barely see them, and the windshield wipers would take about 6-7 seconds to make one full sweep across. Then if I'd sit there gassing it, it would be back up to nromal juice. It did appear to be the altenator.

 

[01EB5.0]

sounds like it is normal. As long as tyhe needle doesn't drop out of the "normal" zine it is OK. The reason it doesn't do it when cold is the engine runs a little big faster when cold until it reachesa a certin temp., then it will idle a bit lower. also when it is in drive the endine will idle a bit slower too..in neutral or park there is no load on the engine and then the alternator can spin faster. It is just because the alternator isn't spinning as much as it needs to. as long as the gauge is in the normal zone it's good..my mom's 94 ford econoline van has had the voltage gauge dip down when the blower is on and headlights since it was brand new.

 

[Raceit]

Thanks for all the feedback. At this point I think I'm going to get a new one. Despite what you said 95XLT
Something about the needle moving around like that when stopped gets me worried being on a trail or something. Not moving very fast, stuff like that. Then running lights and other crap.
So I may try to find a local 130amp alternator from a local place here so I don't have to pay shipping on my core.
Again, thanks for the help. I sure love this board!