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Drive Belt Tension Check

Generator and Air Conditioning Compressor Drive Belt Tension Check
Check the drive belt tension by the following procedure.







Required Special Tools:
MB991502: Scan Tool (MUT-II)
MB991668: Belt Tension Meter Set




1. Connect special tool MB991668 to scan tool MB991502.

CAUTION: To prevent damage to scan tool MB991502, always turn the ignition switch to "LOCK" (OFF) position before connecting or disconnecting scan tool MB991502.

2. Connect scan tool MB991502 to the data link connector.





3. Turn the ignition to the "ON" position and select scan tool MB991502 "Belt Tension Measurement" from the menu screen.
4. Hold special tool MB991668 (microphone) to the middle of the drive belt between the pulleys (at the place indicated by an arrow), about 10 - 20 mm (0.4 - 0.8 inch) away from the rear surface of the belt and so that it is perpendicular to the belt (within an angle of ± 15 degree angle).

CAUTION:
- The temperature of the surface of the belt should be as close as possible to normal temperature.
- Do not let any contaminant such as water or oil get onto the microphone.
- If strong gusts of wind blow against the microphone or if there is any source of loud noise nearby, the values measured by the microphone may not correspond to actual values.
- If the microphone is touching the belt during the measurement, the values measured by the microphone may not correspond to actual values.
- Do not take the measurement while the vehicle's engine is running.

5. Gently tap the middle of the belt between the pulleys (the place indicated by the arrow) with a finger as shown in the illustration. Check that the vibration frequency of the belt is within the standard value range.
Standard value: Vibration frequency: 134 - 159 Hz







Use a belt tension gauge to check that the belt tension is within the standard value range:
Standard value: Tension: 490 - 686 N (110 - 154 lbs.)







Apply 98 N (22 lbs.) of force to the middle of the drive belt between the pulleys (at the place indicated by an arrow) and check that the amount of deflection is within the standard value range.
Standard value: Deflection (Reference value): 8.5 - 10.9 mm (0.33 - 0.43 inch)