Variable Valve Lift Mechanism Check: Notes

Required Special Tools: 

• MB992744: Vehicle communication interface-Lite (V. C. I.-Lite)
• MB992745: V. C. I.-Lite main harness A
• MB992747: V. C. I.-Lite USB cable short
• MB992748: V. C. I.-Lite USB cable long
• MB991958: Scan Tool (M. U. T.-III Sub Assembly)
  • MB991824: Vehicles Communication Interface (V. C. I.)
  • MB991827: M. U. T.-III USB Cable
  • MB991910: M. U. T.-III Main Harness A (Vehicles with CAN communication system)

1. Turn the ignition switch to the "LOCK" (OFF) position.
2. Remove the variable valve lift control motor. (Refer to VALVE LIFT CONTROL MOTOR  ).
3. Visually check the position of the worm wheel through the variable valve lift control motor mounting hole. If the gear teeth is visible as shown in figure A, go to Step 4. If the gear teeth is not visible as shown in figure B, go to Step  5.
   Fig 1: Identifying Coupling And Worm Wheel Gear (Teeth Visible)

   
   Fig 2: Identifying Coupling And Worm Wheel Gear (Teeth Not Visible)

   
   CAUTION:

   • To avoid damage to the oil seal, make sure that the circumference of the socket is not scratched.
   • To insert a socket, apply engine oil to its circumference and the oil seal lip to avoid damage to the oil seal fitted in the variable valve lift control motor mounting hole.
   • Be careful not to damage the oil seal lip when inserting and pulling out the socket.
   • Keep the socket end 5 mm from the rocker shaft holder end when turning the coupling as the tool may trap the holder. Failure to do this will cause measurement errors.
4. Insert a 12-point socket (24 mm) with a mini torque wrench into the coupling. Check rotational torque by turning the coupling counterclockwise.
   • If the rotational torque is 0.7 N.m or less, go to Step 5.
   • If the rotational torque is more than 0.7 N.m and 3 N.m or less, turn the coupling counterclockwise once while keeping the torque 3 N.m or less. After completion of the repair, perform road test to check whether the malfunction occurs again.
     Fig 3: Turning Coupling Anti-Clockwise

     
   • If the rotational torque exceeds 3 N.m, replace the rocker arm and camshaft assembly. (Refer to >> A << ROCKER COVER ASSEMBLY INSTALLATION  ).
5. Remove the rocker cover assembly. (Refer to ROCKER COVER ASSEMBLY  ).
6. Visually check the rocker arm and camshaft assembly for missing, breakage, falling off, jammed foreign matters, etc.
7. Rotate the crankshaft clockwise. Align the timing mark of the rocker shaft holder with the one circular timing mark of the V. V. T. sprocket. Therefore, the No. 1 cylinder is set at the top dead center on its compression stroke.
   Fig 4: Identifying Timing Chain Timing Mark

   
8. Insert a 12-point socket (24 mm) into the position on the coupling approximately 5 mm away from the rocker shaft holder. Connect the mini torque wrench.
   Fig 5: Checking Rotational Torque Using Tool

   
9. Perform the visual check of the worm wheel. If the jam occurs at the position where the worm wheel pushes the minimum lift stopper or the maximum lift stopper, rotate the mini torque wrench to the following direction releasing the jam. Check the rotational torque and perform the conformity determination as follows:
   Fig 6: Identifying Worm Wheel Components