I just upgraded my wifes 77 MGB with a new rebuilt GM internal regulated alternator from a later Chevy application. It's the same one I have on the 68 Camaro. While finishing up the job, I found that the alternator pully gets extreamely hot after just a few (30) seconds of running while the body of the alternator seems to be normal. The belt runs very true, and is not too tight. It puts out about 14.5 volts and keeps the battery fully charged. The Camaro's pully doesn't get hot at all. Do I have a problem?? Thanks Kevin

Your belt is slipping. No other cause for this that I know of. Tighten her up.

A deep grove pully will run a little hotter than a standard one. How hot is it getting? If you spit on it, will it sizzle? Is it a segmented belt or solid? The key factors you described are the main issues - (true and correct tightness).

It got hot enough to leave a red mark. I don't think it would sizzle, but I sure don't want to touch it again if it stays like that. It doesn't smoke squeak or smell. It's just a regular solid belt, but with a deep groove pully. The longest run is about 18 inches with about 1/2 to 3/4 inch flex. I hope that would be enough. I'll try tightening it up a little. I was thinking bearing or something like that. Wish me luck. Thanks Kevin

Kevin, I also think that the belt might be too loose. If it's a new belt as well, they will stretch after a bit and require retightening. Grab a hold of the belt (while the engine is off of course!!!) and the pulley and see if you spin the alternator pulley. If you can spin it, the belt is too loose.

Could the pulley be too wide for the MG belt?