Drive Belt Tensioner: Testing and Inspection

AUTO-TENSIONER CHECK

OPERATION CHECK

Required Special Tool:

MB992278: Belt tension release wrench

1. Stop the engine from the idle state.

2. Remove the radiator condenser tank. Service and Repair).

3. Check that the drive belt is not protruding from the pulley width of the auto-tensioner.

4. Remove the drive belt (Refer to Service and Repair).





5. WARNING:
Always work from above when releasing the tension of the auto-tensioner. When you try to gain access from underneath the vehicle, you will experience difficulty, thus causing the tool to be dropped off.

CAUTION:
To work at the optimum angle, you must choose a most suitable box-type wrench is applied to the special tool.

WARNING:
Be sure to set the box-type wrench and the special tool MB992278 to the hexagonal parts securely to prevent the tool from falling off because the tension of the auto-tensioner is high.

Install special tool MB992278 and a box-type wrench at the optimum angle.
6. Check that no binding is present by turning the auto-tensioner in the left and right directions.
7. If there are any problems in the procedure 3 or 6, replace the auto-tensioner (Refer to Service and Repair).
8. Install the drive belt. (Refer to Service and Repair).
9. Install the radiator condenser tank. Service and Repair).

FUNCTION CHECK

The auto-tensioner can be checked whether it is in good condition by checking its tension.

[When the vibration frequency is measured: Recommendation]

Required Special Tools:

- MB992080: Belt Tension Meter Set
- MB992081: Belt Tension Meter
- MB992082: Mic Assembly

1. Check the tension of the drive belt. (Refer to Drive Belt Tension Check and Adjustment).









2. Check the tension of the drive belt in the following procedures.
(1) Connect special tool microphone assembly (MB992082) to special tool belt tension meter
(MB992081) of special tool belt tension meter set (MB992080).
(2) Press the "POWER" button to turn on the power supply.
(3) Press the numeral key of "1" and check that "No. 1" appears on the upper left of the display.
NOTE:
This operation is to temporarily set the preset data such as the belt specifications, because if the measurement is taken without input of the belt specifications, conversion to tension value (N) cannot be made, resulting in judgement of error.

(4) Press "Hz" button twice to change the display to the frequency display (Hz).
(5)

CAUTION:

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

Hold special tool MB992080 to the middle of the belt between the pulleys (at the place indicated by arrow) where it does not contact the belt (approximately 10 - 15 mm (0.4 - 0.59 inch) away from the rear surface of the belt) so that it is perpendicular to the belt (within an angle of ± 15 degrees angle).
(6) Press the "MEASURE" button.
(7) Gently tap the middle of the belt between the pulleys (the place indicated by the arrow) with your finger as shown in the illustration, and check that the vibration frequency of the belt is within the standard value.
Standard value (Reference): 97 - 124 Hz
NOTE:
To take the measurement repeatedly, tap the belt again.

(8) Press and hold the "POWER" button to turn off the power supply.
3. If not within the standard value, replace the auto-tensioner. (Refer to Service and Repair).

[When using a tension gauge]

1. Check the tension of the drive belt. (Refer to Drive Belt Tension Check and Adjustment).





2. Use a belt tension gauge in the middle of the belt between the pulleys shown in the figure
(at the place indicated by the arrow) to check that the belt tension is within the standard value.
Standard value (Reference): 262 - 430 N (59 - 97 lb)
3. If not within the standard value, replace the auto-tensioner. (Refer to Service and Repair).