Cylinder Head

Remove air cleaner, spark plug wire tube and valve cover. Disconnect battery ground cable and drain cooling system. Disconnect fuel line at fuel pump and accelerator linkage.
Disconnect all fuel and vacuum lines, along with all wiring from injection system and cylinder head. Disconnect accelerator linkage.
Remove upper front cover. See ENGINE FRONT COVER & OIL SEAL . Bend back lock tabs and remove camshaft sprocket bolts and sprocket. Remove timing chain tensioner plug, spring and piston. Disconnect water hoses at base of intake manifolds.
Disconnect exhaust pipes. Remove cylinder head bolts and install aligning pins to keep rocker arm shafts from moving. Remove cylinder head.

Fig 1: Cylinder Head Tightening Sequence
Courtesy of BMW OF NORTH AMERICA, INC.
To install, reverse removal procedure. Thoroughly clean mating surfaces and install a new gasket with sealer. Tighten bolts to specifications in sequence shown in illustration.
NOTE: Tighten bolts in 3 stages. See Tightening Specifications .

Never loosen bolts during tightening sequence; turn only in tightening direction.
Install camshaft sprocket and timing chain in correct position. See TIMING CHAIN REPLACEMENT . Install valve cover and tighten nuts to specification.
After installation is complete and engine has run for a short time, shut off and allow to cool to approximately 100°F (38°C). Retighten cylinder head bolts to specification in same sequence.