In order to un bolt the cylinder head from an N52 engine one has to note that the aluminum stretch bolts should be replaced every time they are taken out for use and the specific torque should be applied using an angle protractor. To start off, the negative terminal of the battery should be disconnected and the vehicle should be properly jack up and supported. The engine compartment splash shield can now be taken out and with the exhaust system still cold, both exhaust systems and both exhaust manifolds should now be disconnected. Siphon out the engine coolant as well as engine oil and thereafter take out the ignition coil cover, the air filter housing together with other bits such as the engine air intake ducts and the intake manifold. After that, remove the cylinder head cover and remove the coolant hoses to the cylinder head. Engage the crankshaft and then use the vibration damper bolt to turn the crankshaft until cylinder one is at TDC; check that the intake and exhaust camshaft part numbers are correctly aligned. 20 Insert the BMW special tool to lock the crankshaft at TDC through the bell housing flange port. Using a Special tool again apply the lock to the camshafts of the engine, then put out the intake and exhaust camshafts adjustment units by unscrewing the bolt and throwing away the units. taken out the timing chain tensioner avoiding any splatter of oil, and disconnect the timing chain from the camshaft adjustment unit sprockets. At the front end of the cylinder head, there are several timing chain module mounting bolts that must be removed in addition to 'unclipping' the chain module. This is in a bid to prevent the timing chain from jamming once you have removed the crankshaft locking tool. Unbolt and take out the valvetronic eccentric shaft sensor, it is dangerous if the magnet wheel non-magnetic mounting bolt falls off into the engine. Lift the eccentric shaft and take the stop screw between cylinder 1 and 2. Take out the cylinder head bolts on the timing chain housing as the rail of the timing chain housing has to be slightly pushed forward to tighten the bolts and the bolts are made up of Aluminium which have to be discarded. Take the proper BMW special tools and then, in the sequence mentioned, loosen the M9 and M10 cylinder head bolts and then remove them and always make sure to write their lengths. Finally, I formally bolt the lifting handles on the cylinder head and lift it off with help in a realization to put it on its side to prevent bending the valves and cleaned any anti-freeze from the bolts in the crankcase.