You will need: a 17 mm open-end wrench, a 10 mm socket wrench, a special key for turning the tension roller or two drills of the appropriate diameter, a screwdriver and a mounting blade.
1. Disconnect the wire from the "-" terminal of the battery.
2. Remove the alternator belt (see "Replacing and adjusting the tension of the generator drive belt").
3. Set the piston of the 1st cylinder to the TDC position (see "Setting the piston of the first cylinder to the TDC position of the compression stroke").
4. Loosen the tension roller mounting nut.
5. …and remove the washer, and then the tension roller from the stud.
Note: There is a spacer ring installed under the roller.
6. Check the bearing for proper operation. If you feel any binding or axial play when turning the bearing, or if you see signs of grease leaking from the bearing, replace the tension roller.
7. Install the new tension roller in the reverse order of removal. The holes for the special key should be facing outward.
8. Adjust the tension of the camshaft drive belt and check the alignment of the valve timing marks on the camshaft and crankshaft pulleys (see "Replacing the camshaft drive belt and adjusting the belt tension").