At 11:45 PM 2/7/02, Rob wrote:
When cold my 90 S4 will hold a steady voltage of 13.5 volts at idle or in motion. As the car starts to warm up the volt gauge will intermittently drop down to 11.5 volts and primarily when the car is in gear. Radiator fans have some effect but the major contributor is the air/heater blower and air conditioner. Also if I turn my fog lights on the voltage goes up .5 to .75 of a volt, I contribute that to a better ground path being established.
I have replaced the alternator, battery and resister bridge, cleaned the grounds above the relay/fuse panel and the ones under the pod, engine to frame and the two in front of the radiator. .
When the RPM's are above 800 everything seems to be OK, no lack of power or hesitation and charging stays at about 13.25 to 13.5 volts. Another remote factor could be my bad motor mounts stretching a wiring harness someplace. Any recommendations?
Slim possibility, but belt tension or belt wear could be a factor. If you use the Porsche belt tension gauge to set the ribbed alternator belt, it is astonishingly tight. Very few people will set the belt that tight without the gauge.