This procedure applies to M10 and M30 engines.
The top cover of the timing chain can be removed separately. If you need to remove both the top and bottom covers, you will need special tools. Before starting work, read points 8 and 9.
Withdrawal
1. Disconnect the negative battery cable.
If your car's radio is equipped with an anti-theft system, make sure you have entered the correct code before disconnecting the battery.
If, after connecting the battery, the inscriptions on the instrument panel appear in the wrong language, refer to Section Anti-theft audio system and instrument panel language, for instructions on how to set the desired language.
2. If you remove the bottom cover of the timing chain (top cover can be removed separately), remove the cooling fan and fan shroud, radiator and fan drive belt pulley (see chapter Cooling system).
3. Only on the M10 engine, remove the water pump (see chapter Cooling system).
4. On engines where the distributor cap is mounted directly on the timing chain cover, remove the distributor cap, slider and black plastic cover under the slider (see chapter Car maintenance).
5. On the M30 engine equipped with the L-Jetronic fuel system, remove the distributor from the top cover of the distribution chain (see chapter Ignition system).
6. Remove the cylinder head cover (see Section Removal and installation of a cover of a head of cylinders).
7. If you are removing the lower timing chain cover from the M30 engine, remove the crankshaft pulley from the vibration damper/hub. Hold the pulley stationary on the center bolt with a replacement head, and drive the pulley bolts with another replacement head.
8. If you are removing the lower timing chain cover, remove the damper/hub by blocking the crankshaft and loosening the large center bolt. Since this bolt is very tight, you will need a long collar and a replacement head. On M30 engines, BMW recommends using a 3/4 inch socket and collar, as the center bolt is especially tight on them. To block the crankshaft while loosening the bolt, use the original BMW tool no. 11 2 100 (or its equivalent).
9. On M10 engines, if you could not purchase the special tool described in the previous paragraph (8), you can try to block the crankshaft by removing the flywheel / drive plate cover and inserting a wide-blade screwdriver into the teeth of its crown. On M30 engines, after the center bolt has been released, it may be necessary to use a puller with a hook to remove the vibration damper from the crankshaft. Place the grip on the inside groove of the pulley and very slowly tighten the center bolt of the puller, all the while checking that the pulley is not bent.
If the pulley is stuck to the crankshaft, you can try lubricating the hub area with a little penetrating oil and then lightly tap it with a hammer.
10. Unscrew the plug and remove the timing chain tensioner spring.
11. The tensioner plunger may come out with the spring. If not, remove the plunger from the tensioner spring hole. To check the operation of the plunger, see Section Removal, inspection and installation of the distribution chain and sprockets of its tensioner.
The spring is in a compressed state, and this can cause the plug to be thrown out of the hole abruptly. Hold the plug while unscrewing and release the spring slowly.
12. On M30 engines, if you remove the upper distribution cover, unscrew the thermostat cover and remove the thermostat (see chapter Cooling system).
13. On M30 engines, if you remove the lower distribution cover, loosen the alternator mounting bolts and move the alternator to the side. Loosen the front lower mounting bracket bolt and loosen the remaining bolts. Also unscrew the mounting bracket of the power steering pump and move it to the side.
14. Give nuts and bolts of fastening of the top cover of a distributive chain to the block of cylinders and remove a cover. Draw a simple bolt pattern to install them in the same holes they were removed from when reassembling. Remove the upper timing chain cover. If it sticks to the cylinder block, gently tap it with a rubber-faced hammer, or attach a block of wood to it and tap it with a hammer. On M30 engines equipped with the L-Jetronic fuel system, remove the distributor drive shaft.
15. Give nuts and bolts of fastening of the bottom cover of a distributive chain to the block of cylinders. Don't forget to give the bottom three bolts securing the front of the oil pan to the bottom of the front cover.
16. Loosen the rest of the oil pan bolts.
17. Pass a thin, sharp knife between the oil pan gasket and the lower timing chain cover, thus separating the gasket from the cover. Be very careful not to damage or stain the gasket so that you can use it again later.
18. Destroy the gasket sealant between the lower timing chain cover and the cylinder block by tapping the cover with a rubber-faced hammer or a regular hammer with a block of wood. Do not poke anything between the cover and the block to avoid damaging the gasket surfaces.
19. Using a scraper, remove all traces of the old gasket material from the mating surfaces of the covers and cylinder block.
Be extremely careful not to damage or scratch the soft aluminum surfaces. Also, be careful not to damage or stain the oil pan gasket. There are commercially available, and may be useful, special solvents for removing gaskets. Once the gasket material has been completely removed, the gasket surfaces can be degreased by wiping them with a cloth soaked in a suitable solvent.
Installation
1. Replace front oil seals (see Section Replacing the front seals). It is not worth the risk of leaving the old oil seals, because. replacing them with the covers removed is not difficult. Don't forget to put some oil on the lips of the front seals.
2. Apply a light coat of RTV type sealant to the oil pan gasket surface mating with the lower timing chain cover. Apply more sealant to the edges where the gasket meets the cylinder block.
If the oil pan gasket is damaged, then instead of completely replacing the gasket, you can try cutting off the front of the gasket where it meets the cylinder block, then cutting off the front of the new gasket so that it is exactly the same size.
3. Cover the inside surface of the sump with a piece of rag, then clean off all traces of the old gasket material from the mating surfaces. Attach a piece of new gasket to the sump with special adhesive, then apply RTV sealant as described at the beginning of this paragraph.
4. Lubricate both sides of the new gasket with RTV sealant, attach the lower timing chain cover to the front of the engine. Fit the bolts and tighten them to the required torque. Tighten the bolts one by one in a crosswise pattern to do so evenly.
First tighten the bolts securing the lower cover to the cylinder block, then the bolts securing the oil pan to the cover. If the gasket is protruding over the lid-to-block connection or is wrinkling at the lid-to-sump connection, cut it to fit properly.
Once the RTV sealant has been applied, assembly must be completed within 10 minutes to allow the sealant to cure.
5. Install the top timing chain cover in the same way as the bottom cover. If the gasket protrudes above the cover-to-cylinder block connection, cut off the excess with a razor.
6. Perform the rest of the installation procedure in the reverse order of removal.