Usage:
Valve Lash
Preparing To Check Adjustment
- 1. Stop the engine.
- 2. Remove the flywheel housing timing cover(s).
REMOVING TIMING COVER(S)
- 3. Wipe the base of the valve cover(s) to keep dirt from getting into the valve mechanism.
- 4. Remove the valve cover(s).
- 5. Move the compression release lever to the START position, if engine is so equipped.
COMPRESSION RELEASE LEVER
- 6. Bar the flywheel counterclockwise. Align the "TC 1" timing mark on the flywheel with the timing pointer on the flywheel housing.
- 7. Observe the rockers for cylinder No. 1. Determine if the piston is on COMPRESSION or EXHAUST stroke:
COMPRESSION STROKE: Both inlet and exhaust valve rockers can be moved freely.
EXHAUST STROKE: Only inlet valve rocker(s) can be moved freely.
Numbering Of Cylinders And Valve Location
D342 ENGINES
D343 ENGINES ONLY
D353 ENGINES
- 8. With NO. 1 CYLINDER ON COMPRESSION STROKE, check the lash of the following valves; adjust if necessary.
- 9. With NO. 1 CYLINDER ON EXHAUST STROKE, check the lash of the following valves; adjust if necessary.
- 10. Bar the flywheel one revolution in the direction of normal rotation and align the flywheel "TC 1" timing mark with the timing pointer.
- 11. Set the remaining valves as specified in the remaining chart.
Adjusting Valve Lash
D342 and D353 Engines
- 1. Loosen the locknut on the adjusting screw.
LOOSENING LOCKNUT
- 2. Hold the locknut and turn the adjusting screw to obtain the proper lash.
ADJUSTING VALVE LASH
- 3. Hold the adjusting screw and tighten the locknut.
- 4. Recheck the lash.
D343 Engines
- 1. Insert a cross point (Phillips) screwdriver in the hole in the side of the cam follower and engage the cam follower adjuster gear.
- 2. Turn the screwdriver clockwise to increase lash or counterclockwise to decrease lash.
- 3. Recheck the lash.
ADJUSTING VALVE LASH (D343 Engine only)
CHECKING VALVE LASH
Valve Rotators
Checking Rotation
After checking all valve clearances, and before installing the valve covers:
- 1. Start the engine.
- 2. Move the governor control to low idle position.
- 3. D342 and D353 Engines: Watch the serrations on each valve retainer. Each valve retainer should turn slightly each time the valve closes.
D343 Engines: Watch the cam followers. Each cam follower should slowly rotate while the engine is running. However, cam follower rotation does not necessarily indicate valve rotation.
If it is suspected a valve is not rotating, contact your Caterpillar dealer. Repairs must be made to prevent burning the valve.
If all valves rotate, proceed as follows:
- 4. Stop the engine.
- 5. Inspect and install valve cover gaskets. Install new gaskets if necessary.
CHECK VALVES FOR ROTATION (D342 shown)
- 6. Install the valve covers.
- 7. Install the flywheel housing timing cover(s).