Loosen the cylinder head bolts.
Unscrew the thermostat housing and remove the housing together with the thermostat.
Unscrew the camshaft position sensor and pull it out together with the gasket.
Unscrew the top cover of the gearbox and remove the cover. Remove the rubber gasket from the bottom cover.
Cut from the inside out and remove the gasket between the cylinder head and the upper edge of the lower cover. The gasket should be replaced. A separate gasket for the upper gearbox cover is also supplied as a spare part.
Turn the engine to the right by the central bolt of the crankshaft pulley until cylinder 1 is set to the top dead center position. The arrow on the chain sprocket should point upwards.
Secure the camshafts using the BMW tool shown in the figure.
Unscrew the camshaft sprocket. Press the tension roller by the hexagon and relieve the chain. Remove the chain sprocket.
Remove the guide and tension bars from the cylinder head.
Caution: Before loosening the cylinder head bolts, turn the crankshaft back 45 degrees. This eliminates the possibility of valves and pistons touching. After installing the cylinder head, return the crankshaft to the top dead center position of cylinder 1.
Loosen the cylinder head bolts in several passes from the outside to the inside. A special Torx key is required to loosen the bolts, such as the BMW 11 2 250.
Installation
Measure the flatness of the cylinder head and engine block with a steel ruler in the longitudinal and transverse directions and, if necessary, mill it (work at a service station). The maximum permissible non-flatness is 0.03 mm.
Thoroughly clean the cylinder head holes from oil and other objects. Note: There should be no oil left in the blind holes, otherwise the bolts will not fully tighten the cylinder head, although they will be tightened to the required torque. In addition, the engine block may crack.
Install the cylinder head while pushing the pressure bar outward.
Tighten the cylinder head bolts in three passes each time in sequence 1 through 10:
- 1st pass: tighten the bolts in sequence 1 to 10 with a torque wrench to a tightening torque of 30 Nm.
- 2nd pass: tighten the bolts with a hard wrench to 90°.
- 3rd pass: tighten the bolts with a rigid wrench to 90°.
Caution: Tighten the cylinder head bolts very carefully. Before tightening the bolts, check the accuracy of the torque wrench. In addition, a protractor, such as the HAZET 6690, is required to tighten the cylinder head bolts. If you do not have a protractor, place the wrench on the bolt head, apply a square to the wrench handle and mark the desired angle with chalk. Then turn the wrench handle in one pass to the line marked with chalk.
Tighten the guide and tension bar mounting bolts on the cylinder head.
Turn the crankshaft to the top dead center position of cylinder 1, while the locking rod should be inserted.
Press the hex key and put on the sprocket with the chain. The arrow on the sprocket should point upwards. Align the slots in the middle.
Tighten the 4 sprocket bolts to 10 Nm.
Caution: Remove the crankshaft locking device.
Clean the contact surfaces under the top cover of the gearbox.
Check the integrity of the rubber gasket between the upper and lower gearbox covers and replace if necessary. The convex part of the gasket should fit into the groove in the cylinder head.
Replace the paper gasket of the gearbox covers. Cover the gasket joints on the cylinder head with sealing compound "3 Bond 1209".
Apply a thin layer of grease to the upper side of the rubber gasket and the BMW device. Before installing the gearbox cover, the device is placed on the rubber gasket. In addition, 2 BMW bolts 11 4 110 are screwed in to guide them into the upper threaded hole. Instead of BMW bolts, you can also use a thin sheet of tin and 2 studs.
Push the gearbox cover forward, insert the bolts and tighten until their heads touch. Unscrew the devices.
Put on the cylinder head cover without the gasket. Screw in the MB bolts with the large washers "arrows", while the gear box covers are pressed down until the upper edge of the gear box covers is level with the cylinder head. In this position, tighten the cover bolts with a torque of 10 Nm. Remove the guide bolts and screw in the remaining bolts instead with a tightening torque of 10 Nm.
Unscrew the cylinder head cover and screw it back on, installing the gasket. Tighten the bolts crosswise with a torque of 10 Nm.