Valve Clearance: Adjustments

Operation number: 21433-3

Valve clearance check, adjustment

Note! Some variation in the illustrations may occur, but the essential information is always correct.






Removal

Note! Removal steps in this procedure may contain installation details.

Replace the valve cover as necessary. Refer to: Valve cover, B6324S5 Service and Repair

Preparations




To ensure that the valves lie correctly in their seats, carefully tap on the valve stem ends. Use a drift made of plastic, brass or aluminum to protect the valve and the surface of the valve lifter. The sound that arises during tapping will indicate if the valve is properly positioned.





999 7257 Wrench 999 7257 Wrench
Rotate the engine 30 degrees (clockwise) to prevent the valves from colliding with the pistons when the camshaft is rotated.





Refit all exhaust valve lifters following the markings made during removal.
If the markings are gone or if a new cylinder head is to be adjusted, use a valve tappet with a 2.905 mm thickness as base.





999 7281 Press tool 999 7281 Press tool
Position the exhaust camshaft and screw it down toward its bearing seats. Start in the center and screw the bearing caps down alternatingly. Do not tighten.

Measuring valve clearance





Note! Measurements should only be taken on a cold engine. A suitable temperature is approximately 20°C (68°F).

The camshaft cams on the cylinder whose valves are to be measured should point straight up in the direction of the valves.
Tighten the screws of the press tools. M7. Refer to: Tightening torque, B6324S5 Tightening Torque
999 5752 Feeler gauge 999 5752 Feeler gauge
Press with your finger so that the feeler gauge lies parallel with the top of the lifer (see figure). In order to obtain as correct a reading as possible, move the feeler gauge laterally when measuring clearance.
Valve clearance measured on a cold engine (approx. 20°C/68°F) should be: Exhaust valve: 0.45 ± 0.05 mm.










999 7261 Position sensor 999 7261 Position sensor
Repeat the work by loosening the screws of the press tools and rotating the camshaft until the next cam pair is correctly positioned. Tighten and continue measuring until all exhaust valves have been measured.
Note the results carefully.

Correcting measured clearance
Remove the press tools. Lift off the camshaft. Adjust clearance by replacing the lifter. Alternative lifters are available as a spare part/spare part kit. Reinstall the camshaft and press tool. Tighten to 17 Nm. Check valve clearance again on the adjusted valves.

When correct valve clearance has been measured
Remove the press tools.

Install the valve cover. Refer to: Valve cover, B6324S5 Service and Repair.