How to Replace an Alternator in Pontiac Cars

by Contributing Writer

The Pontiac car alternator is designed to act as a generator, producing electrical power to keep the battery charged and running. The Pontiac car has had problems with the electrical systems in the past, with wires corroding and shorting out some of the systems. You may find yourself needing to replace the alternator due to malfunction in the charging system or because of worn parts.

Under The Hood:

 How to Replace an Alternator in a 2004 Grand Prix

Disconnect the negative cable from the battery using a wrench to loosen the terminal nut. Some engines have a cross-brace; if your car is one of those, remove the bolts and take out the cross-brace.

Remove the mounting bolts from the coolant reservoir and move it off to the side. Do not disconnect the reservoir hose.

Turn the adjusting bolt counterclockwise with a socket and ratchet and lift the belt off of the alternator pulley. Unplug the voltage regulator harness from the alternator. Remove the electrical leads from the alternator using a wrench to remove the nuts.

Remove the bolts from the alternator with a socket and ratchet and pull it off of the engine.

Put the new alternator on the engine and tighten the mounting bolts with the socket and ratchet. Connect the electrical leads and tighten the nuts with the wrench. Plug the voltage regulator into the alternator.

Attach the coolant reservoir to the car in its proper location and tighten the bolts with the wrench. If your car has the cross-brace, reinstall it and tighten the bolts with the socket and ratchet. Connect the battery terminal and tighten the terminal nut with the wrench.

Items you will need

  • Socket-wrench set

  • Open-end wrench set

 How to Replace an Alternator on a Pontiac Montana

Detach the negative battery cable from the battery of the Pontiac Montana with an open end wrench and move the cable so that it is not touching any metal objects.

Locate the alternator in the front of the engine on the passenger side of the engine compartment. The alternator will be on the top, side of the engine with a belt running to the crankshaft pulley.

Unfasten the electrical wire connector from the alternator by using a socket wrench to undo the nut and take the electrical wire connector off the terminal.

Loosen the bolts holding the alternator in place with a socket wrench just enough so that you can move the alternator on the bracket, and take the alternator belt off the pulley. Note: Do not remove the belt from the crankshaft pulley.

Undo both bolts on the alternator with a socket wrench until you can remove the bolts completely and take the alternator out of the bracket, removing it entirely from the engine compartment.

Position the new alternator in the bracket and slide the bolts back into place, tightening the bolts with a socket wrench until you can just barely slide the alternator on the bracket.

Place the alternator belt around the alternator pulley and check the position of the belt around both the crankshaft and alternator pulleys to verify that it is seated properly.

Place a crow bar between the alternator and engine block and pull back on the alternator with the bar to add tension to the belt.

Tighten the bolts on the alternator with a socket wrench while you keep the tension on the alternator belt.

Reattach the electrical wire connector to the alternator terminal by placing the connector and the nut on the terminal and securing with a socket wrench.

Connect the negative battery cable to the battery of the Pontiac Montana with an open end wrench.

Items you will need

  • Open end wrench

  • Socket wrench

  • Crow bar

 How to Replace the Alternator in a Pontiac Grand Am

Determine which alternator your Pontiac Grand Am will need. You'll want to be sure the new alternator is compatible with your Grand Am's engine. Models made from 1973 to 1975 may have a 6.5 L or 7.4 L engine. The next generation of the Pontiac Grand Am was built from 1985 to 1991 and was equipped with 2.3 L, 2.4 L, 2.5 L and 3.0 L engines.

Look at more recent versions of the Grand Am. Models made from 1992 to 1998 may have a 2.3 L, 2.4 L, 3.1 L or 3.3 L engine. The latest generation of the Pontiac Grand Am was manufactured from 1999 to 2005 and may have a 2.2 L, 2.4 L or 3.4 L engine.

Disconnect the negative battery cable with a socket wrench. Remove the air cleaner and the bolt on the oil dipstick tube so you can move the tube aside.

Remove the accessory drive belt and the electrical connectors from the alternator. If you have a 3.4 L engine, you will also need to disconnect the power steering-to-alternator line clip. Take the mounting bolts (and nuts for a 3.4 L engine) off of the alternator with a socket wrench and remove the alternator assembly.

Install the new alternator assembly and tighten the mounting bolts to 15 foot pounds with a torque wrench for most models. Torque the nuts on the alternator to 22 foot pounds and the bolts to 37 foot pounds if you have a 3.4 L engine.

Connect the power steering-to-alternator line clip if you have a 3.4 L engine. Plug in the electrical connectors to the alternator and install the drive belt. Reposition the oil dipstick tube to its original position and tighten the bolt for the oil dipstick tube with a socket wrench. Replace the air cleaner assembly and connect the negative battery cable.

Items you will need

  • New alternator

  • Socket wrench set

  • Torque wrench

 How to Replace the Alternator in a Pontiac Grand Prix

Determine which alternator your Pontiac Grand Prix will need. You'll want to be sure the new alternator is compatible with your Grand Prix's engine. Models made from 1962 to 1968 will have a 389 cubic inch (ci), 400 ci, 421 ci or 428 ci engine. Models built from 1969 to 1972 may be equipped with a 400 ci, 428 ci or 455 ci engine.

Look at later generations of the Pontiac Grand Prix. Models made from 1973 to 1977 may have a 231 ci, 350 ci, 400 ci or 455 ci engine. Models built from 1978 to 1987 have 231 ci, 252 ci, 265 ci, 301 ci, 305 ci and 350 ci engines. Models manufactured from 1988 to 1996 can be equipped with a 2.3 L, 2.8 L, 3.1 L or 3.4 L engine.

Examine the most recent versions of the Pontiac Grand Prix. Models made from 1997 to 2003 will have a 3.1 L or 3.8 L engine. The last generation was produced from 2004 to 2008 and had a 3.8 L, 3.8 L supercharged or a 5.3 L engine.

Disconnect the negative battery cable and the accessory drive belt with a socket wrench. Remove the engine sight shield if you have a 5.3 L engine.

Unplug the electrical connectors from the alternator. Unfasten the nut for the positive battery terminal with a socket wrench and remove the battery wire from the terminal.

Remove the bolts from the rear brace and mounting bolts for the alternator with a socket wrench. Remove the alternator assembly.

Install the new alternator assembly and tighten the mounting bolts to 37 foot pounds with a torque wrench. Connect the electrical connectors and battery terminal wire to the alternator and torque the retaining nut to 15 foot pounds. Install the rear alternator brace and torque the bolts to 37 foot pounds. Install the drive belt and the engine sight shield for a 5.3 L engine. Connect the negative battery cable with a socket wrench.

Items you will need

  • New alternator

  • Socket wrench set

  • Torque wrench

 How to Replace the Alternator in a Pontiac Bonneville

Determine which alternator your Pontiac Bonneville will need. You'll want to be sure the new alternator is compatible with your Bonneville's engine. The Pontiac Bonneville has a long production history of unrelated vehicles. The last generation was made from 2000 to 2005 and was available with a 3.8 L L36, 3.8 L L67 and 4.6 L LD8 engine.

Look at earlier generations of the Pontiac Bonneville. Models made from 1977 to 1981 have 231 ci, 265 ci, 301 ci, 350 ci or 400 ci engines. Options for 1982 to 1986 include a 231 ci, 305 ci, 2.8 L, 4.3 L or 350 ci diesel engine and 1987 to 1999 models have a 3.8 L engine.

Disconnect the negative battery cable with a socket wrench and the supercharger belt, if present. Remove the accessory drive belt and fuel injector sight shield, if needed, to access the alternator.

Remove the nut and bolt on the brace for the alternator and the retaining nut for the wiring harness with a socket wrench. This will allow you to disconnect the electrical wiring from the alternator. Take the two mounting bolts off of the alternator with a socket wrench and remove the alternator assembly.

Install the new alternator assembly and tighten the mounting bolts to 37 foot pounds with a torque wrench. Connect the wiring to the alternator and torque its retaining nut to 111 inch pounds. Torque the nut for the alternator brace to 37 foot pounds and the bolt to 22 foot pounds.

Attach the fuel injector sight shield and the accessory drive belt. Install the supercharger belt, if present, and the negative battery cable with a socket wrench.

Items you will need

  • New alternator

  • Socket wrench set

  • Torque wrench