1966 loose alternator belt

[nobadlie]

I changed the alternator and tighten the belt, but after driving for a while I noticed the belt loose. So, I got under and tighten the belt again and drove it for awhile and again noticed the belt loose. Any suggestion on what is causing this?

[Rusty57]

First look at the basics.

Mark the position of the alternator bracket/adjuster arm when the belt is tight. That way you can determine if it slipped or the belt stretched if it becomes loose again.

Did you tighten the pivot bolt for the alternator after you made the adjustment?

Are you using a belt tension gauge or just tightening it by feel? If so you might be getting it too tight and stretching the belt.

The next time it is loose remove the belt from all the pulleys. Check each one to determine if it has any looseness or wobble. For example, if the water pump bearing is going bad it will just get worse and relieve the tension on the belt.

[David Langhorne]

First of all belts do stretch a little when new. Also I read that alternator belts need to be tightened more than the old dynamo belts. I tighten mine using leverage on the alternator to get it as tight as possible. If I don't then it squeals under load.

[Rt.146]

The long alternator bolt with spacer, can become stripped, though it will tighten to a point not as exactly as it should, this could be a problem you are having, with the loosening.

[nobadlie]

Thanks for all the good info.