Hi guys. This is one real pile that GM came up with. Repair parts are available now from aftermarket suppliers but it's a huge waste of time trying to fix it. By the time you unsolder the stator windings from the flimsy tabs on the diode block, that block will be junk. You can't test the voltage regulator so to be safe, you might as well replace it too. At that point you've spent more on parts than a rebuilt one costs. Most of the early generators were sealed too. Snapon, and probably the other tool truck guys, have tools to get the sealed ones apart.
Evey year in my Automotive Electrical class, I had my kids disassemble alternators to see how they worked, and to test parts. We don't do that in the real world anymore because time is too valuable and if we mess something up, we have to warranty our own repair. Unit replacement is faster, more efficient, and saves the customer money in the long run.
Every year I made sure at least one of my students tried to disassemble an '87 or newer GM generator to see how long it would take before they were ready to throw the pile on the floor and stomp on it! They had probably the world's second best generator up through the '86 model year, so they had to change it.
I should mention too that repeat failures of these generators is extremely common, not for locked up bearings, which are also common, but for shorted diodes and failed regulators. The cause is the huge voltage spikes these units develop due to their design. To reduce the repeat failures, many professionals are finding out replacing the perfectly good battery at the same time is the solution. As they age, they lose their ability to dampen and absorb those spikes. Besides taking out the diodes and voltage regulator, those spikes can radiate into computer sensor signal wires and make the many computers do strange things. Very often you'll hear that someone's car runs better when the small plug on the generator is disconnected. Usually a new battery solves that.
Wednesday, August 10th, 2011 AT 4:55 AM