Engine body Stripping of cylinder head I nspection of cylinder head The flatness tolerance for the cylinder head is max. 0.12 mm (.00472"). Check in six positions ("A-F" as per Fig. 15 and 16). Use a feeler gauge and a ruler the sides of which are precision rubbed as per DIN 874/Normal. 1. Valve lock 4. Valve 2. Valve spring washer 5. Valve cap* 3. Valve spring *MD2040 and later versions of MD2010 , 2020, 2030 Fig. 14. Dismantling the valves Fig. 15. Checking of cylinder head flatness 1. Remove the valves and valve springs. Press the springs together with a valve spring tensioner and remove the valve lock. Place the valves in order in a marked valve rack. Remove the valve stem seals. 2.
Clean all parts. Observe special care with the channels for oil and refrigerant. Fig. 16. Checking of cylinder head flatness 3. Remove residual soot and impurities from the cylin- der head's sealing surfaces. Note: Do not use use steel brush to clean the cylin- der head screw threads or under the screw heads. I f the flatness is not within the permissible tolerance the cylinder head should be replaced. If leakage or blow marks are confirmed it is not necessary to check for flat- ness since the cylinder head must be replaced. Check the valve seats and that the pin screws are tight. For replacement of the valve seats (inlet) see next page. 2 7