The Screaming Jaguar
 

HellO Good People...

Looking for some leads or to be pointed in some directions.

Warm weather or cold every time I start up my 1990 XJS 5.3 the alternator will scream for the first 20 to 30 seconds. Maybe more. I keep my eye on the gauge, it starts LOW then quickly climbs out of LOW and into the normal range (a little higher than mid "normal" in fact). Then, screaming stops... At the battery I have 14.10 - 14.15 steady and easy.

Battery is new. Well, it was not long ago. I have replaced the negative terminal clamp at bat... I have cleaned grounds at battery to chassis and others that I have found under the bonnet. At the firewall and around the rad. Then others, thinking that might be it. I have also removed the connects to the alt and no change. Maybe I noticed brighter lights here and there?

What's else could it be? I don't want to buy a new alternator,,, lol. I just dont!

Hi Jay

I have had the same problem myself about 3 Years ago, which turned out to be the bearings binding in the Alternator (which had probably gone dry)

So what I did was to get a long screwdriver and dip it in some oil, then dropped a few drips just behind the Alternator Pulley Wheel so that it got onto the Alternator Drive Shaft

Where it eventually worked its way into the bearings and its been running Silent ever since!

Also check the Tension on the Drive Belt, although I think dry bearings are the problem

The most obvious thing I would check is the tension on the drive belt as OB says.
The belts wear as they get older and slip on the pulley until sufficient heat builds up to make it grip again; usually about 20-30 seconds......
You can check the belt tension by pushing inwards on the belt; there should only be about 1/2 to 3/4 of inch movement, any more and it is too slack and you need to move the adjuster to take it up.
I have a slightly different problem which I think is the bearing in that my alternator chirps every second or so and the lights dim and brighten in time with it.
Either that or the hamster on the treadmill is getting old.

So - I checked the belt tension last night and it seemed fine... Maybe tonight after work I will give it a few turns and try the few drops oil approach. Its an odd thing...

I was thinking,,, maybe it has something to do with the ground on the starter....? Or main engine to chassis ground? Something's gotta give!

Oh and,,,, Yes - them hamsters do be getting old, lol... Just hate when they all get woreD out at the same time. AARP for the XJS hamsterz!