Join Date: Nov 1999
Location: Palm Beach Gardens, FL
The regulated voltage DOES decrease with increase in temperature, this is normal. If the alternator gets too hot, for whatever reason, it won't destroy itself.. It shouldn't drop below 13V. If you have a '94, it's a 3G; you didn't say where you got your replacement. There's a lot of junk automotive electrical and hard to tell what's good and what isn't. I couldn't tell by looking at it and I'm an electrical engineer.
It could be your computer; if you could measure the current draw from the alternator (a DC clamp meter will do the job, if you can borrow one), you would know right away what's happening. No alternator can put out full load current for very long. The higher the load, and the longer it runs, the hotter it will get, so maybe the regulator and alternator are fine and trying to tell you something. A 130A 3G has a continuous rating of 80-100A. The lower end in the summer and the higher end in the winter.
1988 GT, 57k mi, Orig Owner
ProCharger P600B, FRPP Headers, Flowmaster F2, 3G Alt, Mk8 Fan/DCC, 3.55's, Prog Springs, ST Brace, G/Trac Bar, Subfrms, UCA, LCA, FCA, Tokico 5-ways, C/C Plates, CSA 16x8, Bridgestone RE760 Sport 225/50R16, Megasquirt DIYPNPF60, LC2 WBO2, C&L76mm MAF w/LU47's