[Noah]

Took off my 60A Plane Power Alternator to inspect the brushes since I've gone over 500 hrs in the past year. Plenty of meat left on the brushes but I found this:

Anybody seen this sort of elongated mounting hole? This is the upper bolt hole which swivels to allow belt to be tensioned by tightening lower bolt. Not sure of the cause, I have checked and adjusted belt tension at every annual, bearings are good, haven't had any problems with this alternator.

How about a repair? I was thinking of boring oversize and making a bronze bushing. Or is there a better way?

 

[RVDan]

I have seen this before. It happens when the through bolt isn't tightened, which needs to be done after you adjust the belt tension.

 

[BillL]

I would agree to the cause - if it has good area contact on both sides, I would just tighten it back up good and check on oil changes. If tight, it won't be moving anyway, the sides keep it aligned. No harm.

Funny it has lasted so long, maybe being loose allowed it to live longer?? I wonder? . . . .. nah.

If it really bothers you, machine out the hole on original center and make a new bushing from steel.