How to Replace the Alternator in a Chevy Cobaltby Robert Moore; Updated November 07, 2017
Items you will need
Memory saver unit
That alternator on your 2010 Cobalt is located on the front, passenger side of the engine. You can follow the same procedure regardless of what engine you have. You'll need basic hand tools and a torque wrench to complete the procedure. To prevent premature wear to the alternator, make sure the battery is fully charged before starting the engine for the first time after completing this repair.
Install a memory saver unit to the vehicle according to its manufacturer's instructions. Open the trunk. Remove the trunk floor mat and set it aside. Loosen the negative battery cable nut, using a socket and ratchet. Disconnect the negative cable from the battery and place it aside.
Open the hood. Loosen the clamp that secures the air intake tube to the air filter housing and the engine, using a Phillips screwdriver. Slide the tube off the housing and remove it from the engine. Disconnect the wiring harness from the MAF sensor. Remove the two nuts for the air filter housing, then lift the air filter housing out of the engine bay.
Make a sketch of the belt routing, using a pen and paper. Locate the square hole in the belt tensioner arm, and slide the head of a 3/8-inch-drive ratchet into the hole. Rotate the tensioner arm counterclockwise. Remove the belt from the pulleys, then slowly release the tensioner arm.
Disconnect the wiring harness from the alternator. Remove the terminal nut, then remove the battery cable from the alternator. Support the alternator by hand, then remove the three alternator bolts. Remove the alternator from the engine bay.
Hold a new alternator in position and install the mounting bolts. Tighten the bolts to 16 foot-pounds, using a torque wrench. Install the battery cable to the alternator terminal, then tighten the nut to 15 foot-pounds. Plug the wiring harness into the alternator.
Turn the tensioner pulley and air-conditioning compressor pulley by hand. Replace either one if there is any resistance or play in the pulleys. Inspect the serpentine belt. Replace the belt if there is any lengthwise cracking, fraying or glazing of the present.
Route the serpentine belt around all of the pulleys except the alternator pulley -- follow the sketch you made. Rotate the tensioner arm counterclockwise and slip the belt onto the alternator pulley. Slowly release the arm to apply tension to the belt. Make sure the belt sits between the outer walls of each pulley. Adjust the belt by slightly releasing tension, if needed.
Install the air filter housing. Tighten the retaining nuts to 13 inch-pounds. Install the air intake tube to the air filter box and the engine, then tighten the clamp. Connect the wiring harness to the MAF sensor. Shut the hood.
Connect the negative battery cable to the battery. Tighten the battery cable nut to 13 foot-pounds. Install the trunk floor mat. Shut the trunk lid. Disconnect the memory saver device.