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2.1.7. Removal, survey and installation of a distributive chain and asterisks of its natyazhitel

This procedure belongs only to M10 and M30 engines.


After installation of the engine in the provision of VMT do not turn distributive or cranked shaft until the distributive chain is established. If to turn a cam-shaft or the crankshaft at the removed distributive chain, valves can strike pistons, having caused serious internal damages of the engine.

Removal

 PERFORMANCE ORDER

  1. Bring the cylinder No. 1 into the provision of the top dead point (TDP) of a step of compression (see the Section Reduction of the Piston of the First Cylinder in the provision of the top dead point (TDP)).
  2. Uncover a head of cylinders (see the Section Removal and installation of a cover of a head of cylinders). Once again make sure that the cylinder No. 1 is the provision of VMT of a step of compression and its yoke do not squeeze a spring of valves.
  3. Remove the top cover of a distributive chain (see the Section Removal and installation of covers of a distributive chain). Notice the provision of distributive tags of a cam-shaft which have to be combined now. On four-cylinder engines (M10) on a flange of a cam-shaft it is beaten usually out risk which coincides with the acting tag in the top part of a head of cylinders; besides, the opening of an adjusting pin of an asterisk of a cam-shaft will be in the lowermost point. On six-cylinder M30 engines the line drawn through two opposite bolts of an asterisk of a cam-shaft will be absolutely vertical while the line drawn through two other bolts will be precisely horizontal. Besides, the adjusting pin has to be in the bottom left corner (in situation "between the 7th and 8 hours"). Before dismantling make sure that you correctly defined the provision of VMT for a cam-shaft since correctness of a step of valves depends on whether precisely you leveled them at assembly.

As the engine is installed in a motive compartment at an angle, all installations of vertical and horizontal position have to be made in relation to the crankshaft, but not to the earth.

  1. Fix a bent shaft in an immovability on the central bolt of a damper by means of a replaceable head and a ratchet, then weaken (but do not turn off completely) four bolts of fastening of an asterisk of a cam-shaft to a cam-shaft. Be very careful not to turn the crankshaft or a cam-shaft.

On some earlier models there can be lock uvulas for cam-shaft asterisk bolts. In this case before weakening of bolts unbend uvulas down. Such uvulas are not issued producers any more, and at assembly they will not be necessary.

  1. Remove the lower cover of a distributive chain (see the Section Removal and installation of covers of a distributive chain).
  2. Give four bolts of fastening of an asterisk of a cam-shaft, then separate a chain from an asterisk of a bent shaft and carefully remove it and an asterisk of a cam-shaft from the engine. Perhaps, it will be required to hook slightly a cam-shaft asterisk the screw-driver.

Survey

Distributive asterisks

Examine teeths of asterisks of a cam-shaft and the crankshaft on existence of signs of wear. Each tooth is the turned letter "V". At wear one side of each tooth under the influence of tension will be slightly concave in comparison with other party (i.e. one party of the letter "V" will be more concave, and the letter will seem bent). If teeths look worn-out, the asterisk should be replaced.

Asterisk of the crankshaft of a napressovan on a shaft, and it can be removed by means of a stripper with capture, after removal of a segment spline and the oil pump (see the Section Removal, check of a state and installation of the oil pump). However experts of BMW recommend to napressovyvat a new asterisk on the crankshaft, its heating to temperature 80o With for M10 engines and 200o With for M30 engines. For this reason if the asterisk of the crankshaft demands replacement, we recommend to remove the crankshaft (see the Part of the Procedure of capital repairs of components of the engine of this Chapter) and to carry it in a mechanical workshop for removal of an old asterisk and a napressovka new.

Distributive chain

The chain should be replaced if asterisks are worn-out or the chain weakened (points excessive noise to it during its work). Every time at capital repairs of the engine is the best of all to replace a chain. At strongly worn-out chain on tension rollers small flutes can be formed. In order to avoid problems in the future if you have any doubts concerning a condition of a chain, replace it.

Guide and natyazhitel of a chain

 PERFORMANCE ORDER

  1. Examine a guide of a chain and a boot of a natyazhitel on existence of the deep flutes which are formed as a result of contact with a chain. If they are too worn-out, replace them. Guides can be replaced, having removed lock rings by means of any sharp tool or nippers.
  1. Shake a plunger of a natyazhitel and listen as the ball valve rattles. If it does not rattle, replace a plunger.
  2. For further check of a plunger of a natyazhitel, blow at first through his closed end, then - through the end with a cut (directing). At a purge through the closed end air should not pass through it, and at a purge through the end with a cut - opposite, has to pass freely. If the plunger did not undergo this testing, replace it.

Installation

 PERFORMANCE ORDER

  1. Establish a boot of a natyazhitel and a guide of a chain if they were removed.
  2. Temporarily spread the lower cover of a distributive chain and a damper of tortional fluctuations. To check distributive tags of the crankshaft. After check of combination of tags of VMT remove a damper and a cover.
  3. Establish a distributive chain on a crankshaft asterisk, then on a cam-shaft asterisk, and having carried out it between a guide of a chain and a boot of a natyazhitel, establish a cam-shaft asterisk on a cam-shaft. Check combination of distributive tags of a cam-shaft.
  4. You make the rest of the procedure of installation as it should be, the return to removal. Do not forget to tighten fixture with the required effort.