Greetings folks. Been free of issues in my 86 xj6 for a while now until a week ago.
I’m pretty sure my alternator is starting to go -
my battery light come goes on and off but battery is brand new / full of juice.
The battery gauge on the dash tells another story. The dial isn’t leaving the red area. I used to tap the cover and it would move to 14-15 but now after tapping - it barely moves. It has been running a little rougher and slightly noisier in the belt area.
I’ve never checked the juice in the alternator so is there an easy way to do that before bringing it in for service ?
Any advice / feedback always greatly appreciated.
thanks in advance

 

mmm possibly the alternator

I would do a few simple tests first.

If you have a new battery I will assume the terminals are clean and tight
I would do a visual inspection of the alternator drive belt, is it tensioned properly ? (say 1/2 inch or 1 cm deflection on the longest run when you nudge it engine off)
Get a meter , start the car and measure the voltage at the +ve battery post. Should be a steady 14V (give or take) with the car running. If lower check the alternator output (stay away from the rotating fan blades) If low at the alternator , I would replace it.

I had something vaguely similar and it ended up being belt/pulley related do to my car being a conversion, and this particular area not being very well done. (bit odd with the eleventy billion options you have for small block chev accessory drives)