Pistons — Removal and Installation (Mercedes-Benz Vario 814)

Removal

1. Remove the engine.

2. Remove the cylinder head.

3. Remove the oil pump.

4. Unscrew the bolts securing the connecting rod caps 1. Connecting rod 2 and connecting rod caps 1 are installed according to the side mark (arrow) (figure 2.40).

Text republished from the website MercedesMan.ru

Figure 2.40. Pistons: 1 - Connecting rod cover; 2 - Connecting rod; 3 - Bolts; 4 - Piston; 5 - Retaining ring; 6 - Piston pin; 7 - Tension band.

5. Remove the connecting rods 2 together with the pistons 4 through the top of the cylinder block. If the pistons are worn, their direction of movement may be invisible due to carbon deposits. Therefore, it is necessary to remove the carbon deposits in order to determine the location of the direction of movement arrow.

6. Using a screwdriver, remove the retaining ring 5 of the piston pin 6. Do not damage the piston.

7. Press out piston pin 6 and remove piston 4.

Installation

8. Check the inner diameter of the connecting rod upper head bushing. If it is more than the permissible value, replace the bushing.

9. Lubricate the piston pin 6 and the bushing of the upper connecting rod head.

10. Install the piston on the connecting rod with the arrow pointing in the direction of movement. The mark and the locking slots on the connecting rod must be located on the left (from the intake manifold side).

11. Push the piston pin in by hand.

12. Insert the retaining ring 5 into the groove (arrow) on the piston.

13. Lubricate the cylinders, crankshaft journals, liners and pistons with oil.

14. Install the tension band 7 for the piston rings and tighten it.

15. Install pistons 4 with the arrow pointing in the direction of movement.

16. Check the connecting rod cap mounting bolts. Replace them if necessary.

17. Install the connecting rod caps 1.

18. Tighten the connecting rod cap mounting bolts to a torque of 42 Nm + 90° (figure 2.41).

19. Check the clearance by rotating the crankshaft.

20. Install the oil pump.

21. Measure the piston protrusion. Install a cylinder head gasket of normal thickness or replacement thickness (1.85 mm) depending on the piston protrusion.