In case of removal of the power unit, disconnect the gearbox from the engine.
Disconnect wires from spark plugs. By BMW «525» And «528» remove the wire attachment tube on the cylinder head cover and the ignition distributor assembly.
Remove the ignition distributor bracket mounted on the end of the camshaft.
Remove the carburetor and intake manifold.
On the model «520i» (with fuel injection engine «KugeHischer») disconnect the fuel supply pipelines to the injectors from the injection pump, disconnect the fuel line from the starting injector and the starting system power supply wire.
Remove the protective casing and exhaust manifold, alternator, starter, cylinder head cover, fuel pump and its pusher.
Remove the camshaft timing chain tensioner spring and plunger while holding the spring in place.
Remove the top cover of the timing mechanism drive, unscrew the bolts securing the camshaft sprocket by removing the locking plates.
Move the sprocket and chain forward away from the engine.
Loosen and remove the cylinder head bolts in the reverse order of tightening.
Remove the cylinder head and gasket.
Remove the water pump assembly.
Remove the protective cover of the flywheel ring gear, block the flywheel from turning with lock 6069.
Unscrew the nut securing the crankshaft pulley, remove the pulley.
Remove the bottom cover of the distribution mechanism drive by unscrewing the bolts of its fastening to the block and the oil sump. At the same time, push the cover forward to remove it from the dowel pins on the cylinder block.
Remove the camshaft sprocket and timing chain by marking the front side with paint. Remove the chain guide and chain tensioner shoe.
Loosen the bolts securing the flywheel housing to the flywheel and remove it complete with the pressure plate. This releases the clutch disc. Pay attention to its position: the protruding part of the hub is directed towards the pressure plate.
Loosen the flywheel mounting bolts, remove the retainer 6069, remove the flywheel.
Remove the crankshaft rear oil seal holder, then press out the oil seal.
Drain the engine oil, turn the engine upside down and remove the oil sump.
Remove the oil pump (see above).
Check the markings of the connecting rod caps and main bearings (caps are counted from the camshaft drive side) and, if necessary, label them.
Loosen the nuts of the connecting rod bolts, remove the connecting rod caps and the lower connecting rod bearing shells and put them in order.
Carefully remove the pistons with connecting rods through the cylinders and place them next to the corresponding connecting rod caps and connecting rod bearing shells.
Remove the main bearing caps along with the lower bearings. Remove the crankshaft from the bearing seats. Remove the upper main bearing shells and put them in order.
Disassemble the cylinder head (see above).