3BJQ60000-0 Tohatsu GEAR CASE

Valve Lash Check
A valve lash adjustment is not necessary if the measurement of the valve lash is in the acceptable range. The acceptable range is given in Table 1.
Table 1
Valve Lash Check(1)
Valves Acceptable Range
Inlet 0.52 to 0.68 mm (0.020 to 0.027 inch)
Exhaust 0.92 to 1.08 mm (0.036 to 0.042 inch)
(1) The valve lash check should only be done while the engine is stopped.Use the procedure that follows in order to check valve lash:
Rotate the No. 1 piston to the Top Center position. Refer to System Operation, Testing And Adjusting, "Finding the Top Center Position for the No. 1 Piston". With the No. 1 piston at the Top Center position of the compression stroke, check the valves.
Adjust the valve bridges. Refer to "Bridge Adjustment".
Insert the 6V-3075 Dial Indicator from the timing group into the 4C-6593 Adjustment Tool. Tighten the retaining screw finger tight. Note: Make sure that the 6V-3075 Dial Indicator is used with the short contact point.
Use the threaded hole that is nearest to the end of the rocker arm that will be adjusted in order to install the adjustment tool on the rocker base. Position the dial indicator stem over the flat area on the end of the rocker arm. Tighten the knob. Rotate the dial indicator so that the dial indicator can be easily read. Make sure that the adjustment tool is rigid and that the dial indicator stem moves freely.
Lift up firmly on the end of the rocker arm that has the adjustment screw and set the dial indicator to zero.
Lift up firmly on the valve end of the rocker arm and read the dial indicator.
Try to move the rocker arm while you are lifting up on the rocker arm. The dial indicator reading will vary. Read the dial indicator when the rocker arm is positioned in the groove of normal operation. Refer to Table 1 for the specifications regarding valve lash . If the dial indicator reading is within specifications move to the next valve.
If the dial indicator reading is not within specifications reset the valve lash. After the adjustment is complete proceed to the next valve. Refer to "Valve Lash Adjustment".
After completing all of the valve lash checks and the valve lash adjustments for this crankshaft position, remove the timing pin from the crankshaft. Rotate the crankshaft to the next position. Install the timing pin in the crankshaft. Repeat Steps 2 through 8.
Remove the timing pin from the crankshaft when all valve lash adjustments have been completed. Valve Lash Adjustment
The procedures for engine valve lash should be performed according to the information in the Service Manual.Operation of Caterpillar engines with improper valve adjustments will reduce engine efficiency. This reduced efficiency could result in excessive fuel usage and/or shortened engine component life.
Table 2
Setting The Valve Lash(1)
Valves Dimension Of The Feeler Gauge
Inlet 0.60 mm (.024 inch)
Exhaust 1.0 mm (.039 inch)
(1) The valve lash should only be adjusted while the engine is stopped. Use the procedure that follows for adjustment of the valves:
Rotate the No. 1 piston to the Top Center position. Refer to System Operation, Testing And Adjusting, "Finding the Top Center Position for the No. 1 Piston". With the No. 1 piston at the Top Center position of the compression stroke, adjust the valves.
Adjust the valve bridges. Refer to "Bridge Adjustment".
Insert the 6V-3075 Dial Indicator from the timing group into the 4C-6593 Adjustment Tool. Tighten the retaining screw finger tight. Note: Make sure that the 6V-3075 Dial Indicator is used with the short contact point.
Use the threaded hole that is nearest to the end of the rocker arm that will be adjusted in order to install the adjustment tool on the rocker base. Position the dial indicator stem over the flat area on the end of the rocker arm. Tighten the knob. Rotate the dial indicator so that the dial indicator can be easily read. Make sure that the adjustment tool is rigid and that the dial indicator stem moves freely.
Loosen the locknut on the rocker arm adjustment screw and turn the rocker arm adjustment screw clockwise until there is no valve lash. Loosen slightly. The valve lash should be zero. The valves should not be open any amount.
Set the dial indicator to zero.
Lift up firmly on the valve end of the rocker arm and turn the rocker arm adjustment screw until the dial indicator shows 0.60 mm (.024 inch) for the inlet valves, and 1.00 mm (.039 inch) for the exhaust valves.
Try to move the rocker arm while you are lifting up on the rocker arm. The dial indicator reading will vary. Read the dial indicator when the rocker arm is positioned in the groove of normal operation.
Tighten the locknut on the adjustment screw to a torque of 200 25 N m (150 18 lb ft).
Recheck the setting of the valve lash to ensure that the valve lash is correct. Reset, as required.
After completing all of the valve lash checks and the valve lash adjustments for this crankshaft position, remove the timing pin from the crankshaft. Rotate the crankshaft to the next position. Install the timing pin in the crankshaft. Repeat Steps 2 through 10.
Remove the timing pin from the crankshaft when all valve lash adjustments have been completed. The following procedure is an alternate method that can be used for adjustment of the valves:
Rotate the No. 1 piston to the Top Center position. Refer to System Operation, Testing And Adjusting, "Finding the Top Center Position for the No. 1 Piston". With the No. 1 piston at the Top Center position of the compression stroke, adjust the valves. Note: Prior to making any adjustments, tap each rocker arm at the top of the adjustment screw with a soft hammer. Tapping the rocker arm ensures that the lifter roller is seated against the base circle of the camshaft.
Loosen the locknut for the rocker arm adjustment screw. If there is not enough clearance for the feeler gauge between the rocker arm and the bridge contact