Note: This describes the removal and installation of the camshaft for the M51S engine (model 525tds). Instructions for the M47 engine (model 520d) given at the end of the chapter.
Since the work requires a special tool from BMW, it is recommended to perform this work at a service station for BMW cars. The distribution lead can be removed both with the cylinder head removed and installed. Below is a description of the removal of the camshafts with the cylinder head removed. This also applies to the installed cylinder head, however, in this case, it is necessary to carry out preliminary work before the operation of loosening the bolts of its fastening in accordance with the instructions in chapter "Removal and installation of the cylinder head".
If necessary, before removing the camshaft, measure the clearances. Prescribed value of axial clearance: 0.15-0.33 mm; radial clearance: 0.04-0.081 mm.
Withdrawal
Remove cylinder head, see p. 16.
To remove the camshaft, BMW tool 11 3 330 is required. The tool is designed to hold all the camshaft bearings in their mounting position when the caps are loosened. Fit the tool and screw it in with the cylinder head cover bolts, see illustration.
Turn the eccentric shaft of the tool to press the bearing caps.
Loosen all bearing caps.
Loosen and remove the tool.
Remove bearing caps and camshaft. The bearing caps on the exhaust side are marked from 1 to 7.
If you want to (e.g. when valves need to be removed), then remove the valve lifters. At service stations for BMW cars, suction cups are used to remove the pushers, which are attached to the pushers from above. Pushers, if they were removed from the block, must be installed in their original places.
Attention: The removed valve tappets must not be kept upside down for more than 10 minutes, as the engine oil slowly pours out of them, and the automatic clearance compensation in the valve drive stops.
Installation
Attention: If the camshaft was removed, the following must be observed. Hydraulic tappets expand when unloaded on the camshaft side and take some time to recompress after mounting. Therefore, the valves may open for a longer time than determined by the valve timing adjustment and collide with the piston. Therefore, it must be ensured that a certain time is maintained 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 from the cylinder head mounted on the engine, turn the crankshaft of the engine about 30°behind TDC in the direction of its 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 camshaft 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. Each pusher should not be installed in the same place where it was before removal.
Lubricate the camshaft bearings with engine oil and insert the camshaft so that the tops of the cams for the intake and exhaust valves of the first cylinder face the same upwards.
Install the bearing caps in accordance with the markings provided. The caps must be installed in the same places in which they were before removal.
Fit tool and tighten bearing caps.
In ½ turn steps, tighten evenly in a crosswise pattern in sequence "outside - inside" camshaft bearing caps with a torque of 15 Nm.
Loosen and remove the tool.
Install cylinder head.