All BMW gasoline engines except for the S14 and S38 dual overhead camshaft designs and the hydraulic lifter equipped M42 and M50, are equipped with an overhead camshaft operating the intake and exhaust valves through rocker arm linkage.
Valve lash on these engines should be adjusted at intervals determined by the Service Interval lights. See Routine Maintenance and your service manual. It is important to adjust the lash to make up for wear in the valve train, which will cause noisy valve operation and reduced power, or, in some cases, excessive tightness in the valve train, which can cause the valves to burn and may even reduce compression. The BMW features a unique adjuster design that makes it easy to hold the required dimension while tightening the locknut; thus, valve adjustment is unusually easy.