For fitting the cylinder head on the M54 engine, it is necessary to clean the surfaces of cylinder head and gasket for the cylinder block and the timing chain covers free from any sort of deposit, dirt, liquid or any other foreign substance which may damaging the engine block. Do not metal scrape or wire brush the aluminum components; use only a hard wood or plastic scraper or abrasive discs in drills if required. Visually inspect the cylinder head for cracks or other defects and to check the warpage position the intake and exhaust camshaft and inter midiate intake lever for reassembly. Rotate a straight edge along the length of the cylinder head sealing surface both lengthwise and sideways to check levelness, and have the head checked for leaks, and cracks especially around water jackets. If twisted but not damaged beyond the 0.3 mm off the sealing surface, machine it down to this range and use a thicker gasket obtainable from the BMW dealer only. Before assembling apply assembly lubricant on the camshafts, camshaft carriers, bearing caps, hydraulic lifters, and the friction washers. At this stage the position of the two cylinder head aligning sleeves should be correctly positioned and elastic sealing compound applied on corner joints and seam on the cylinder block to timing chain cover. Put on the new cylinder head gasket, aligning the 'UP' mark with the head up; then position the cylinder head and feed the primary chain into the gap. Do not use used cylinder head bolts, for new ones lightly oil new bolts and washers, put them on by hand rotate to cylinder head tightened, then tighten them to the final torque angle in a special sequence in three steps. The next step is to fit the intake camshaft sensor and then the lower secondary chain guide the long bolt which passes on the intake camshaft side should pass through the engine block. Replace the camshafts; be sure to keep the crankshaft in the properly aligned position so that the pistons and valves do not interfere; let hydraulic lifters drop; turn the crankshaft and pistons to TDC. Replace the double VANOS unit, fit the coolant pipe along with a new O-ring and put the oil line for VANOS unit with a new banjo bolt and seals. After that, fit the intake camshaft cover together with the cylinder head cover, exhaust manifolds together with new gaskets and nuts, applying copper paste on the studs of the manifold. Bolt the electrical harness for the oil pressure sender and coolant temperature sensor, on the intake manifold and tighten the throttle harness connector. Finish up the installation by recharging and purging the cooling system, changing the oil and filter and reconnecting the battery point as well as reconnecting all ground wires to prevent bad grounds on the engines electronics then remove crank lock prior to starting the engine.