Timing chain parts on M 123 engine
28 - crankshaft sprocket; 53 - camshaft gear; 85 - right guide; 89 - upper guide; 93 - lower guide; 94 - limit pin; 98 - intermediate gear; a - tensioner
Timing chain parts on M 110 engine
1 - exhaust camshaft gear; 2 - upper guide; 2a - intermediate gear; 2b - lower on the guide; 3 - intake camshaft gear; 4 - guide wheel; 5 - limit pin; 6 - intermediate gear; 7 - distribution chain; 8 - crankshaft sprocket; 9 - rolling axis; 10 - right guide; 11 - hydraulic chain tensioner
Removing the timing chain link
1. Remove the spark plugs and valve cover (right side of engine M 110).
2. If necessary, the cam followers can be removed to make it easier to turn the engine.
3. Rotate the engine two full turns and check that the chain has a connecting link. If there is no such link, place a rag on the cam sprocket and sand down the ends of the axle of one single link.
4. Remove the chain tensioner.
5. Place the replacement link on the cam sprocket, remove the link, and attach the new camshaft chain using the new link. Keep the chain engaged with the sprocket and have an assistant crank the engine while seating the new chain on the sprockets.
6. With the free ends of the chain on the sprocket, insert the link from the back and replace the washers and clamps. If there is only one clamp, its closed end should face the direction of rotation.
7. Install the chain tensioner.
8. Install the cam followers and check the timing.
9. Install the valve cover and spark plugs.