BMW 11120721008 Cylinder Head

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If the engine is in the car, disconnect the battery, drain the cooling system, remove the air cleaner, and disconnect the throttle and choke linkages. Disconnect the downshift cable for automatic transmission and electric choke leads where applicable, along with emission control hoses. Disconnect the fuel inlet pipe at the fuel pump and plug it, and for fuel injection models, disconnect the fuel line at the injection pump. Disconnect the radiator hose from the thermostat housing, the hoses from the inlet manifold and branch pipe connection, and the heater hose from the cylinder head. Pull the leads from the water temperature sender and oil pressure switch, then remove the distributor cap with HT leads and the induction transmitter from the coil for fuel injection models. Remove the oil dipstick support bracket and disconnect the exhaust downpipe and support bracket from the manifold and transmission. Remove the seven nuts retaining the rocker cover, noting the wiring harness clips under certain nuts, and lift off the cover. Remove the eight securing bolts to take off the timing gear upper cover, noting the alternator earth wire under bolt no. 4. Turn the crankshaft by applying a spanner to the crankshaft pulley nut until no. 1 piston is at TDC on its compression stroke, ensuring both valves on no. 1 cylinder are closed and the marks on the distributor rotor arm and body rim are aligned, with the second notch on the crankshaft pulley rim opposite the pointer on the timing chain cover. Mark the relationship of the distributor body to the distributor drive housing, release the clamp bolt, and withdraw the distributor. Unscrew the chain tensioner plug and extract the spring and plunger. Flatten the lockplates and remove the camshaft sprocket bolts while maintaining tension on the chain to prevent disengagement from the crankshaft sprocket teeth, retaining the chain by wiring it to a convenient point on the crankcase. Unscrew the ten cylinder head bolts, releasing them a turn at a time in diagonal sequence, then lift the cylinder head complete with manifolds, carburettor, or fuel injection components as applicable. If the cylinder head is stuck, gently tap it all around with a soft-faced mallet or a heavy hammer using a block of hardwood as an insulator instead of levering it off. To dismantle the cylinder head completely, remove the camshaft and rocker shafts, and to remove the valves, compress the valve springs using a compressor with an extension to reach the deeply recessed valve spring cap. Compress the valve spring, remove the split cotters, and gradually release the compressor until the cap and valve spring can be extracted, then withdraw the valve from its guide. Remove all the valves in turn, retaining them and their components in strict sequence for exact replacement, using a sheet of stout card with holes punched in it and numbered 1 to 4 for the left (inlet) and 1 to 4 for the right (exhaust), with No. 1 at the front of the engine and left and right defined from the driver's seat perspective.

Install the camshaft sprocket, ensuring that the mark on the sprocket flange is correctly aligned to avoid valve damage to the piston crowns.

If the camshaft end float exceeds 0.0005 in (0.127 mm), renew the thrust plate.

Use a blunt scraper to eliminate all traces of carbon and deposits from the combustion spaces and ports, taking care not to damage the aluminum alloy.