From reading through the discussions on troubleshooting a questionable heat soaked alternator there appears to be a few basic steps that continue to be repeated. Please chime in to add your comments and any recommendations -
1) Clean all the major Ground Points
2) Clean/Replace Battery, Jumper post and Alternator Cables
3) Clean the 14 Pin Connector Plug Pins (Razor Blade Spreads Male Term Pins Perfectly)
4) Replace Motor to Frame Ground Strap
5) Check Alt Drive Belt for Condition and Tightness
6) Test Alt Charging Light Circuit
Volt Meter Light On - Key On Engine Not Running
Volt Meter Light Off - Engine Running
7) Alt Not Charging Until RPM @ 2K
Check Voltmeter Light Wiring - Bulb and It's Parallel Resistor
Check D+ Connection @ Alternator
8) Compare Alt Output Voltage @ Battery and Jumper Post
9) Test Alt Voltage @ Idle, Then @ 2K Rpm (Headlights On- Engine Warm)
10) Alt Voltage 13-14 Volts, Loaded Head Lights On - Only When @ 2K RPM
Replace Voltage Regulator
Smaller Pulley
11) Replace Alternator
I had replaced my VR with a Huco Unit, added an insulated heat shield between the alt and engine, refreshed cooling air ducting to the alternator and installed a smaller serpintine pulley on my old Paris-Rhone 90 Amp alternator several years ago.
The most important pulley spec's were the stand off distance measured from the back of the pulley to the 1st groove, the 17mm shaft diameter and the surpintine belt surface diameter @ 48mm - my original pulley dia was 52mm.
So far, this has kept the charging system on Miss Purdy doing fine even at idle without having to replace the std 90 amp alternator with a larger unit.
Michael