GMC 19151861 Reman Alternator (Delco 12Si 78 Amps)

The alternator used in all models is a Delco-Remy Delcotron, with three types available, the 5.5 inch Series 1D and the 10DN Series 10OB and Series 10SI, and one must note that while the types 5.5 inch Series 1D and 10DN require an external voltage regulator, the type Series 10SI has an internal regulator. Care involves now and then removing dust or oil with a soft cloth, checking the tightness of the driving belt, and the fact that no greasing point has ever been needed because the alternator bearings are permanently lubricated for their life. A lot of caution must always be exercised while making the following circuit connections on a car carrying an alternator: whenever charging through an alternator from a battery, always observe correct polarity. When using electric-arc welding equipment, for welding repair, it is necessary to unscrew the connector from the alternator, and the positive terminal of the battery. Never start the vehicle with a battery charger connected, and always remove both battery leads before using such a charger. If charging from another battery, connect in parallel with fat conducts. It is not safe and wise to perform an alternator test at home because it involves use of special testing tools and may lead to damage; thus it is better to let automotive electrical experts in this task.

Disconnect both leads from the battery terminals and the leads from the rear face of the alternator, marking them first to ensure correct installation. Loosen the alternator mounting and adjuster link bolts, push the unit in towards the engine as far as possible, and slip off the drivebelt. Remove the mounting bolts and lift the alternator from the engine compartment. Installation is a reversal of removal, adjusting the drivebelt tension as needed. New alternators typically do not come with pulleys, so the old one should be removed if a new unit is to be purchased; to do this, hold the alternator shaft still with an Allen wrench while unscrewing the pulley nut.

To install an alternator, reverse the removal steps and adjust the belts accordingly.

Begin by removing the alternator and pulley, then secure the alternator in a vice, applying pressure to the mounting flange.

Remove the mounting bolts and lift the alternator from the engine compartment.

Extreme care is necessary; always match the correct polarity when connecting the alternator to a battery, disconnect the connector from the alternator and the positive battery terminal before using electric-arc welding equipment, never start the vehicle with a battery charger connected, and ensure both battery leads are disconnected.

Due to the critical nature of disassembling and testing various alternator components, it may be advisable for the home mechanic to replace a faulty unit with a new or factory rebuilt model.

Install the through-bolt and nut and tighten it securely. Tighten the alternator bracket bolt securely.

Both battery leads must be disconnected before using a mains charger.

Loosen the alternator mounting and adjuster link bolts, push the unit in towards the engine as far as possible, and slip off the drivebelts.

The pulley on the alternator is flat

This alternator is 78 amps