BMW 11121252130 Cover

Refit the oil pump drive chain to the rear teeth of the crankshaft sprocket, then install the double roller timing chain to the front teeth of the sprocket. Allow the oil pump chain to hang downwards pending installation and draw the timing chain upwards to hang over the top of the cylinder block. Ensure that any original chains being refitted have their marks correctly positioned.

Yes, if only the main timing chain is to be removed, this can be done without detaching the sump. However, if the oil pump drive chain is also to be removed, the sump must be detached.

Remove the radiator, lower splash guard, and belts for the alternator, power steering, and air conditioning. Take off the crankshaft pulley and vibration damper. If applicable, remove the crankshaft hub bolt using a gear puller.

Disconnect the negative battery cable and drain the cooling system. - Remove the radiator and fan. - Disconnect electrical plugs, remove the air cleaner, and airflow sensor. - Disconnect alternator wiring, unbolt and remove the alternator and drive belt. - Unbolt the power steering pump, move it aside, and remove the lower oil pan after draining oil. - Loosen oil pan bolts and front cover bolts. - Remove water pump, crankshaft pulley, and timing chain tensioner piston. - Remove timing chain sprockets, guide rail, and distributor components. - Remove upper timing chain guide and sprocket bolts. - Install timing chain, guide rail, and sprockets. - Engage chain with intake sprocket, then exhaust sprocket. - Install tensioner piston and torque it. - Rotate the engine to TDC of cylinder number 1, install upper timing chain guide, ensuring chain alignment. - File cover for smooth fit, replace gaskets with silicone sealer, install front cover and oil pan bolts with proper torque. - Install distributor components, torque oil pan bolts and drain plug, reverse removal steps, refill cooling system and oil pan.