Technical Bulletin
Mitsubishi 4D56/T Valve Clearance: Essential adjustment between valve and rocker arm.
In older applications that do not have a self-adjusting hydraulic tappet / lifter, such as the 4D56, manual adjustment between the rocker arm and valve is a necessity.
When rebuilding the rocker shaft, please adhere to the manufacturer clearance specifications. Step 1. With engine at operating temperature. Ensure timing marks are aligned correctly by rotating the crank manually.
Step 2. When done correctly you will see that following valves in the raised position:
Cylinder 1: Inlet & Exhaust
Cylinder 2: Inlet
Cylinder 3: Exhaust
Adjust clearances according to these steps: Release tension on the rocker nut in preparation for the gauge. Place the correct feeler gauge between the valve and rocker (size specified by the manufacturer). Begin tightening the screw whilst ensuring that the feeler gauge is met but not pinched. Tighten nut to secure setting.
Remove feeler gauge, then reinsert it to check there is a slight interference between the valve and the rocker arm.
Step 3. Manually turn the crankshaft 360 degrees clockwise. Now repeat the method of step 2 whilst focusing on:
Cylinder 4: Inlet & Exhaust
Cylinder 2: Exhaust
Cylinder 3: Intake
Step 4. To ensure the correct clearances are set and maintained, please follow these steps:
Replace rocker cover
Run the engine for 10 minutes
Remove rocker cover and check tolerances are still correct using the same gauge(s).
If necessary, repeat steps 1 to 3.