WATER PUMP DRIVE BELT TENSION CHECK




note An elastic stretch-type belt is used for the water pump drive belt, therefore, the tension adjustment is not necessary.
Check the water pump drive belt tension in the following procedure.

Standard value:
Item
When checked
When adjusted
When replaced
Vibration frequency Hz (Reference)
116 - 337
Deflection mm (Reference)
Less than 20.5

<When the vibration frequency is measured {Special tool (MB992080) is used}: Recommendation>


caution
  • When measuring the vibration frequency, make sure that the engine is cold.
  • Measure the vibration frequency after turning the crankshaft clockwise one turn or more.
note The vibration frequency measuring method is recommended for check of the water pump drive belt tension.

1.Connect the Special tool microphone assembly (MB992082) to the Special tool belt tension meter (MB992081) of the Special tool belt tension meter set (MB992080).
2.Press the "POWER" button to turn on the power supply.
3.Press number key 1. Check to ensure that "No. 01" appears on the upper left of the display and that the following numeric values are displayed for individual items (M, W, and S):
M 000.9 g/m
W 010.0 mm/R
S 0100 mm
If numeric values have not been entered (new tool), set them according to the belt specifications as shown below. Once you set them, you do not have to set them again. The settings remain undeleted even after battery replacement.
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.
<Setting procedure>
(1) Press down the "MASS" button till the belt mass select display appears.
(2) Press the "UP" or "DOWN" button to select "01 1.5GT 0.9" and press the "MEASURE" button to decide it.
Check to ensure that "M 000.9 g/m" is displayed.
(3) Press the "WIDTH" button to change to the belt width input display.
(4) Press number keys 0, 1, 0, and 0 sequentially, and press the "SELECT" button to apply them. Check to ensure that "W 010.0 mm/R" appears on the display.
(5) Press the "SPAN" button to change to the span length input display.
(6) Press number keys 0, 1, 0, and 0 sequentially, and press the "SELECT" button to apply them. Check to ensure that "S 0100 mm" appears on the display.
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 as possible to normal temperature.
  • Do not let any contaminants such as water or oil get onto the microphone.
  • If strong gusts of wind blow against the microphone or if there is 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 the microphone to the middle of the drive belt between the pulleys (at the place indicated by the arrow), about 10 - 15 mm away from the rear surface of the belt and so that it is perpendicular to the belt (within an angle of ± 15 °).
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.
note To take the measurement repeatedly, fillip the belt again.
8.After the completion of the measurement, press and hold the "POWER" button to turn off the power supply.
9.If not within the standard value, replace the water pump drive belt (Refer to ).

<Belt deflection check>


caution
  • When measuring the deflection, make sure that the engine is cold.
  • Measure the deflection after turning the crankshaft clockwise one turn or more.

note The belt deflection check should be just an emergency measure in case that you do not have tools for measuring the vibrational frequency.
1.Apply approximately 98 N of force to the middle of the water pump drive belt between the pulleys (at the place indicated by the arrow) and check that the amount of deflection is within the standard value.
2.If not within the standard value, replace the water pump drive belt (Refer to ).