Why is this sparking? L4240 *picture*

[LADPT]

There is a small arcing here where the metal is making contact. Is there supposed to be a gap there? Supposed to be solid contact? I just noticed, but have no clue how long it’s been going on.

 

[rScotty]

I'm guessing that this alternator has carbon brushes in it and they are about worn out. It's a common maintenance repair in old generators with commutators, but not so much so in alternators.
Anyway, best take it out and to an auto-electric shop and get it rebuilt. Or see if a supplier has brushes for that alternator....always assuming it even has brushes....many alternators do not

 

[Roadworthy]

It is not clear to me where the sparks are happening. Scotty seems to be referring to sparking inside the alternator. Your description sounds more like sparks outside the alternator. You could possibly have a bad ground. Look for something loose or a missing screw.

 

[LADPT]

Ground was definitely not solid. I’ve been needing to address it. So got a new cable and fixed that.

Sparks were coming from outside, where that thin metal piece with welded on nut was contacting the alternator. As the engine vibrated there was contact and it would arc.

I bent it back away with pliers so it’s not doing that anymore, but if I bridge the gap with a screwdriver it still arcs. I don’t think it should be doing that either though.

 

[rScotty]

Ground was definitely not solid. I’ve been needing to address it. So got a new cable and fixed that.

Sparks were coming from outside, where that thin metal piece with welded on nut was contacting the alternator. As the engine vibrated there was contact and it would arc.

I bent it back away with pliers so it’s not doing that anymore, but if I bridge the gap with a screwdriver it still arcs. I don’t think it should be doing that either though.

That desciption matches a connector. Forget the brush idea. Now that you bent the piece away, is the battery still charging?

 

[LADPT]

I’m not sure. It starts stronger since I fixed the ground. However, the batter light on the dash flutters a bit now.