How to replace the serpentine belt on a 1.8L Toyota Corolla, Yaris, Matrix and Pontiac Vibe

    An adjustment bolt on the alternator provides belt tension on Toyota's 1.8L engine. This belt is easier to replace than many, but does require that the alternator mounts are loosened up. This engine was used from 2009 to 2013 and is also found on the Yaris, Matrix, Scion xD and Pontiac Vibe. Shown is a 2010 Toyota Corolla.

                                                                The job at a glance

• Tools: 10, 12 and 14mm 3/8" sockets and ratchet, breaker bar (optional).  
• Materials: none
• Parts: Serpentine belt  
• Cost of parts: Belt $13-20
• Time: 30 minutes

                                                              Removal

     Make note of the belt path for reassembly. I have a drawing of it here.

1) Disconnect the battery with a 10mm socket or wrench

2) Loosen the top 12mm bolt alternator mounting bolt.

The upper 12mm alternator mounting bolt

3) Loosen the lower 14mm alternator pivot bolt. This is where a 1/2" breaker bar can be useful.

The lower 14mm alternator pivot bolt

4) Measure or make a mark on some paperboard of the length of the rearmost  thread on the tension relieving bolt above the alternator. This will help to place the near correct tension back on the belt.

5) Turn the belt tension adjusting bolt counterclockwise a number of turns, pushing the loosened alternator rearward with each several turns. Repeat until near the end of travel on the bolt or the tension is relieved enough to take the belt off the alternator.

Turn the 12mm adjustment bolt counterclockwise to release tension on the belt

6) Remove the belt. 

Re-assembly

1) Re-position the belt over the crankshaft (take care not to get it under the lip of the little timing mark) and ac compressor first, then under the idler and finally up and over the alternator.

2) Turn the adjustment bolt clockwise until the rearmost length of the thread matches up with mark on the paper made earlier. Check the tension on the belt. There should be 1/2" of deflection at the midpoint of the longest straight run of the belt. 

3) Tighten the lower 14mm pivot  bolt.

4) Tighten the upper 12mm mounting bolt, below the adjuster. 

5) Re-connect the battery.

6) Test.