alternator swap

[mike d in md]

hi. i have an 86 safari ( guess it's stock--salvage title) 4.3 my alt bearings are going bad & i have 2 cs alts at my disposal. can i swap a cs type into my 86? what changes in wiring? if i can do this, it'll save $100 i can use elswhere. tia. mike

[Astro95]

I don't know exactly the year GM went to the CS series alternator, but I wouldn't pull a SI and replace it with a CS. They are junk. If you over tighten the BATT terminal nut on the back the slightest amount, it breaks the rectifier bridge and the alternator will fail.

I don't think it would be an easy swap anyway. The case is smaller and the connector on the side is a weatherpack, so you would have to change that.

On the other hand, your old SI alternator bearings are easy to service. The nut that holds the pulley comes off with an impact wrench. Then there are four screws that hold the case together. (Match mark it first because it can go on in any of four different ways.) You pull the front off first, then remove the rotor. The front bearing is held in with three screws. It's a dirt common number 6203. I always keep several on hand because they are used in so many different GM cars for things like accessory drive belt tensioner and idler pulleys. Pack a small amount of heavy grease in the rear shaft bearing. (The rear bearing almost never goes bad unless it's run dry enough to blue the shaft.) Straighten out a large paper clip and run it through the back frame and the brush holder to hold the brushes in while you drop the rotor back into the rear frame. Reinstall the front frame over the rotor and install the four case screws. Use an impact wrench to reinstall the pulley nut and you're done.

[mike d in md]

thanks for the reply. that's the motivation i need to go beyond a 'quick fix' and actually repair it right. mike

[v8famvan]

If you want to upgrade overkill....