[JYD71_454]

The alternator is an internal regulator type that has run fine for years. Not long ago, I noticed the battery wasn't fully charged and checking the alt shows it doesn't really kick in until the engine rpms are up over 2500. It used to kick in at just above idle. All other things being equal, anyone have any ideas as to what may be failing in the alt?

 

[MedicTed]

I know that the F(#@'s have a similar problem. When the ambulances start doing that, one of the diodes has gone bad in the alternator.

 

[Herb]

There's a number of things you can try. But if you are not comfortable tearing down the alternator, consider replacing the whole unit. The diodes, regulator, brushes, can all be replaced at little cost, but if it's old, replacing the entire unit may be the best move due to bearing wear. Replacing bearings is not recommended. Requires a press and damage can occur to the armature, etc. in the process.

What's the voltage at say, 1500rpm? I'm assuming it's an SI?