'67 alternator 'screech'

[Tom Merkel]

This phenomina occurs occasionally on my '67 L-79. The alternator will start 'screeching', as if the bearings dried-up, or some such thing. But it won't do it for long, and always goes away. Occurs at any speed, although it is far more prominent at low speed.

I haven't isolated it to environmental conditions, i.e. hot, cold, rain, etc.

Visually, it shows no wear, tear, burn, etc.

Anyone can shed some light on this, would be appreciated. By the way, it's the original one, never been serviced in any way, and always worked.

Tom

[Donald O.]

Re: '67 alternator 'screech'

Tom,
Are you sure that it is the alternator? It could be a loose belt. I'd check it's tension. If the belt is tensioned properly, then see if you can make it screech with the hood up to help locatye the noise.
Don

[Tom Merkel]

Re: '67 alternator 'screech'

Don - No, I'm not positive it's the alternator, but the screech certainly has a metallic ring to it.

I'll try an pop hood when I hear it next, and see if it is indeed the alternator.

Also, will check belt tension per John H's recommendation, and schedule a re-built/re-furbishment in near term.

Thanks.

Tom

[Duke W.]

Re: '67 alternator 'screech'

When belts get old they can make noise. Check that tension is reasonable - the old one-half to one inch deflection test with your thumb, then, with the engine idling, give the backside of the belt about a two second shot of silicone spray lube, and see what happens. You should also carefully inspect the backside of the belt(s) for tiny cracks or tears. It might just be time for a replacement.

Back in the sixties I recall something called "fan belt lubricant". It was a stick of wax like substance that we would drag along the backside of the belt for a few seconds, and it usually made the squeak go away, but I haven't seen any of that stuff for years.

Duke

[Mike McKown]

Re: '67 alternator 'screech'

Tom:

I have heard this before. Bearing or bushing noise. Sounds as you described, a "screech"! I don't know why it would be intermittent unless it is dependent on the alternator charging to make the noise kick in. Take your belt loose and spin the alternator by hand. If you hear "any" roughness, you have probably found your problem.

Mike

[Tom Merkel]

Re: '67 alternator 'screech'

Mike - Good suggestion. I'll give it a try, and let you know.

Tom