Contents: Checking, adjusting and replacing…↓ Examination ↓ Adjustment ↓ Replacement ↓ Replacing the automatic tensioner ↓
Checking, adjusting and replacing the accessory drive belt
Examination
1. The drive belts for the alternator, power steering pump and air conditioning compressor are located on the right side of the engine. Good condition and correct adjustment of the alternator drive belt play a major role in engine performance. During operation, drive belts are subject to high loads, which causes them to stretch and fail. Based on the above, the condition of the drive belts must be checked periodically.
2. On models produced before 2000, to transmit torque from the crankshaft to the generator, power steering pump and air conditioning compressor (if it is installed) separate drive belts are used; on models produced since 2001, the transmission of torque from the crankshaft to all auxiliary units is carried out by means of a common ("serpentine") drive belt.
3. Without starting the engine, open the hood and locate the drive belt(s). Using a flashlight, inspect the condition of each belt along its entire length. To do this, you need to turn the engine crankshaft, holding the pulley mounting bolt with a head and a ratchet. When unrolling the belt between the pulleys, check its back side as well. The check should be done not only visually, but also by running your fingers over each area. Make sure there are no various types of delamination or cracks. Cracks usually start on the inside and work their way outward. Also, check for any abrasions—they're usually shiny (see figure 9.3).
Figure 9.3. Signs of wear on a poly V-belt - if present, the belt must be replaced.
At the same time, check the condition of the pulleys: there should be no cracks, bending or rust. If any of the above damages is present, the belt must be replaced.
4. The tension of the drive belts on models produced before 2000 is adjusted mechanically, and on later models - automatically. Toyota technicians measure belt tension in pounds of force (lbf) using a specialized dynamometer. Nippondenso and Borroughs dynamometer testers are available from dealers in parts departments. The tester is attached to the short arm of the drive belt, and when tensioned, a reading is read from the scale (see figure 9.4).
Figure 9.4. Installing Nippondenso and Burroughs devices on a drive belt when measuring its tension.
This method is considered the most accurate and purchasing such a tester is highly recommended. When adjusting the belt tension, follow the manufacturer's instructions and Specifications. given in this Guide. The tension values for new belts are slightly higher than for those that have already been used.
Note: A belt is considered "new" if it has not been in use under load for more than five minutes. The remaining belts are considered "used".
5. If you do not have the opportunity to measure the tension of the drive belts with the devices mentioned above, then use the following rule: press hard with your thumb on the middle of the belt between the two pulleys (see Figure 9.5).
Figure 9.5. Press firmly on the belt and check the amount of deflection (models produced before 2000).
The belt is considered to be normally tensioned if you managed to deflect it by approximately 6 mm when the distance between pulleys is 30 cm or less, and about 12 mm when the distance between pulleys is more than 30 cm.
Adjustment
Models produced before 2000
6. When adjusting the tension of the alternator/air conditioner compressor drive belt, loosen the alternator pivot bolt and adjusting lock bolt (models with air conditioning) or an adjusting bolt (models without air conditioning) on the generator bracket. On models with air conditioning, rotate the adjusting bolt and measure the belt tension using one of the methods described above. On models without air conditioning, use a pry bar or other suitable lever to push the alternator up in its bracket. Once the desired tension has been established, securely tighten the pivot and adjusting bolts.
Figure 9.6. Loosen the locking and pivot bolts and turn the adjusting bolt to set the desired tension of the alternator/air conditioner compressor drive belt.
7. When adjusting the tension of the power steering pump drive belt, loosen the pivot and adjusting bolts that secure the pump in the bracket slot and, by moving the pump along the slot in the desired direction, achieve the required belt tension. Tighten the lock bolt and pivot bolt securely.
Models produced since 2001
8. Here the tension of the common auxiliary drive belt is adjusted automatically by means of a spring tensioner.
Replacement
Models produced before 2000
9. When replacing the belt, follow the tension adjustment procedures described above, with the only difference being that after loosening the pivot and adjusting bolts, the driven unit should be tilted toward the center of the engine so as to loosen the tension as much as possible, then remove the belt from the crankshaft pulley and remove it. When replacing the power steering pump drive belt, you will first have to remove the other belts to gain access to it. Since all drive belts are subject to wear at almost the same rate, it makes sense to replace them as a set. Remember or mark the belts and the corresponding grooves on the pulleys to avoid mistakes when installing new belts.
[The material is republished from an online website: TOYOTAMAN]
10. When purchasing a new belt, take the old one with you so that you can directly compare them in length, width and design features.
11. When installing a new belt, make sure that all of its wedges are placed in the corresponding grooves of the pulleys and that the centering is not disturbed when the belt is tensioned (see Figure 9.11).
Figure 9.11. After installing the poly V-belt, check its centering - there should be no displacement in one direction or another.
12. Adjust the tension of the belt(s) in accordance with the above procedures. Please note that the new belt will stretch a little over time - be sure to tighten it after a few hundred kilometers.
Models produced since 2001
13. Loosen the drive belt tension by turning the tensioner clockwise (see Figure 9.13), then remove the belt from the pulleys.
Figure 9.13. To loosen the drive belt tension (models produced since 2001) place an extended open-end wrench or socket with a ratchet on the hexagonal projection of the tensioner and turn it clockwise.
Slowly release the tensioner.
14. Place the belt on the pulleys (see Figure 9.14) and, turning the tensioner clockwise, tighten it, then release the tensioner.
Figure 9.14. Drive belt installation diagram for models produced since 2001.
15. Make sure that the belt is centered and all its wedges are placed in the corresponding grooves of the pulleys.
Replacing the automatic tensioner
Caution: Disconnect the negative (ground) cable from the battery before performing this procedure.
16. If the tensioner does not provide the required tension of the drive belt, jams, or the bearing and/or pulley are worn, it must be replaced. Remove the drive belt (see point 13 and figure 9.13), then unscrew the mounting bolt and nut (see Figure 9.16).
Figure 9.16. Automatic drive belt tensioner on later models, starting from 2001; years, fastened with a nut and bolt.
17. Installation of a new tensioner is carried out in the reverse order to that described in paragraph. 16 order. Tighten the nuts and bolts to the torques specified in Specifications.
18. Install the drive belt (see paragraphs 14 and 15).