Engine body MD2040: Place the expander (2, Fig. 52 on page 38) to the oil scraper rings in the piston ring groove. Check that the ends on the expander do not over- l ap each other. Fit the top scraper ring (1) over the the expander. Put in one end of the ring in the groove and hold it in place with your thumb. Push the ring in position with your other thumb. Fit the lower scraper ring (3) in the same way. Fig. 53. Number marking on connecting rod and cap Check that the scraper rings run easily in both di- rections and that the ends on the expander and the rings are in the correct position (Fig. 52). 3. Check that the marking on the piston top, alt.
in the piston and on the connecting rod, correspond with Fig. 53. Use a piston ring compressor and fit the piston with connecting rod in the respective cylinder, beginning with cylinder No. 1 (first). Note: The connecting rod with the l owest number should be fitted first (to cylinder No. 1) and subse- quently the connecting rod with the highest number closest to the flywheel. i ng (number/colour marking) turned "towards the in- jection pump" (camshaft side). The arrow on the piston top alt. at the gudgeon pin hole should there- by point forwards. The connecting rod should be turned with the mark- Fitting of piston in cylinder Note:
After replacing a connecting rod, piston or gudg- eon pin the weight difference between the connecting rod complete with piston and piston rings must not ex- ceed 10 g (0.35 oz) between the different cylinders. 4. Fit the bearing cap and tighten the connecting rod screws. See "Technical data" for tightening torque. Note: The main bearing cap should be fitted so that the number/colour marking on the crankshaft and cap correspond (Fig. 53). Undamaged connecting rod screws do not need to be changed and can be re-fitted. 1. Lubricate the piston and piston rings with engine oil and turn the rings so that the oil penetrates the pis- ton ring groove.
Turn the piston rings so that the piston ring gaps are divided by 900 from each other. Note: Make sure that no piston ring gap is posi- tioned opposite the piston bolt or at right angles to i t. MD2040: Check that the ends on the expander and scraper rings are in the correct position (Fig. 52). 2. Place the bearing cups in their positions in the con- necting rod and cap. Check that the hole in the bearing cups comes opposite the hole in the con- necting rod. Oil in the crank pin with engine oil. 3 9