Alternator

Hi, this is Bo, an auto expert on RepairPal's Car Genius team! The cylinder-looking piece attached to the ground on your 1991 Nissan D21's alternator is likely a capacitor (or noise suppressor). Its job is to reduce electrical noise that can interfere with the radio and other electronics. While your truck may run fine without it, you might experience more static or interference on your radio if it’s removed. If your new alternator doesn't have one, you can usually transfer it from the old one if you want to keep things quiet. If you need any further advice or want help finding a trusted RepairPal shop in your area, please feel free to call us at 877-913-1554.