Valve Clearance: Adjustments

Valve clearance

Operation number: 21433-3

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.

Remove the valve cover if necessary.

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 for the valve lifter. The sound made when tapping indicates whether the valve is correctly 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 have disappeared or if adjustments are to be made on the new cylinder head, use valve lifters of 2.905 mm in thickness as a base.





999 7281 Press tool 999 7281 Press Tool
Position the exhaust camshaft and screw it down towards its bearing mounting. Start in the middle and screw the bearing caps down alternating. Do not tighten.

Measuring valve clearance





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

Camshaft nodes on the cylinder whose valves are to be measured should point straight up in the direction of the valve.
Tighten the screws of the press tools.
Torque: M7, 17 Nm

999 5752 Feeler gauge 999 5752 Feeler Gauge
Press with your finger so that the feeler gauge is parallel to the top of the lifter (see figure). To ensure that measuring is as correct as possible, move the feeler gauge laterally when measuring clearance.
Valve clearance as measured on a cold engine (approx. 20°C): Exhaust valve: 0.45 ± 0.05 mm










999 7261 Position sensor 999 7261 Position Sensor
Repeat the work by slackening the screws of the press tools and rotating the camshaft until the next node pair is in the correct position. Tighten and continue measuring until all exhaust valves have been measured.
Carefully note the results.

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 tools. Tighten to 17 Nm. Recheck valve clearance on the adjusted valves.





When the correct valve clearance to the exhaust camshaft is reached.
Remove the press tools.
Repeat the steps on the intake camshaft.
Valve clearance as measured on a cold engine (approx. 20°C): Intake valve: 0.20 0+/-0.05 mm.






When the correct valve clearance to both camshafts is reached.
Remove the press tools.

Install the valve cover.