If necessary, before removing the camshaft, measure the clearances. Specified axial clearance (free movement in the direction of the shaft axis): 0.15-0.33 mm; radial clearance (free movement in the direction perpendicular to the axis of the shaft) - 0.02-0.054 mm.
Withdrawal
Remove cylinder head.
Unscrew the pins.
Note: To remove the camshafts, BMW tool 11 3 260 is required. The tool is designed to hold the camshaft bearings in the mounting position when their caps are released. The work steps are the same for both camshafts, the sequence of steps for removal is arbitrary.
Remove spark plugs.
Fit the tool and, using the threaded holes of the spark plugs for cylinders 1 and 4, tighten the tool to 25 Nm.
Turn the eccentric shaft of the tool to press the bearing caps.
Loosen all bearing caps.
Attention: The intake camshaft cover 1 is centered by the guide sleeve. To avoid distortion of the camshaft, unscrew the fastening of the cover and remove the cover.
Loosen and remove the tool.
Remove bearing caps and camshaft. Place the removed covers in accordance with their numbers; during installation, they must be installed again in their original places. The exhaust camshaft bearing caps are marked A1 to A7, and the intake camshaft bearing caps are marked E1 to E7.
If required, for example, when it is necessary to remove the valves, then remove the bearing bed block -2- from the cylinder head -1- complete with valve lifters. Pay attention to dowel sleeves -3-. In the position indicated by the arrow -4-, the bearing bed of the exhaust camshaft is marked "A", and the bearing bed of the inlet shaft - a mark "E".
Caution: If no action is taken, the valve lifters will slide down from the bearing block. The BMW car repair shop uses suction cups that are attached to the pushrods from above and prevent them from slipping out of the bearing bed. Put marks on the pushers. The pushers, if they were removed from the block, must be installed in their original places.
Attention: The removed valve lifters must not be kept upside down for more than 10 minutes, as this will cause engine oil to pour out of them, albeit slowly, and the automatic clearance compensation in the valve drive will stop.
Installation
Attention: If the distribution lead was removed, please pay attention to the following. Hydraulic firebox! The fir-trees without load from the distribution line expand, and after their installation, it takes some time for them to shrink again. Therefore, the valves may open for a longer time than determined by the valve timing adjustment and collide with the piston. Therefore, it is necessary to ensure that a certain time is kept between the installation of the camshaft and the installation of the cylinder head: at +20°C (room temperature) — 4 minutes, at +10°С — 11 minutes. After installing the cylinder head, wait another 30 minutes before turning the engine crankshaft.
If the camshaft was removed with the cylinder head removed, turn the engine crankshaft approx. 30°past TDC in the direction of rotation (to the right, behind the hexagon on the belt pulley). This ensures that no pistons are at TDC and the valves cannot touch the pistons. Install the distribution lead and wait the time indicated above. Only then return the crankshaft to the TDC position and install the camshaft drive chain, see chapter "Removal and installation of a head of cylinders".
Check valve tappets for wear and scratches, replace if necessary.
Lubricate the camshaft bearings with engine oil and insert the camshafts so that the tops of the cams for the intake and exhaust valves of the first cylinder face each other.
Place the bearing bed assembly with the tappets installed on the cylinder head. Make sure that the centering sleeves -3- are in place, see drawing W-10195.
Install the bearing caps in accordance with the markings. The covers must not be installed in the same places they were before removal.
Fit tool and tighten bearing caps.
Tighten the camshaft bearing caps to 15 Nm.
Loosen and remove the tool, screw in the spark plugs.
Install cylinder head.