Installing Piston
WARNING: This page is about a different variant/trim than selected.
Information
- Connecting rod bolts and bearing shells must always be replaced.
- The marking on the main bearings is located on the flywheel flange of the crankshaft.
Information
Surface with cylinder number marking
Allocation
Installed DFI piston in crankcase
- The pistons must already be pre-fitted (pistons, piston rings, connecting rods and fastening material) before performing the next step.
- Fit the number on the connecting rod -A- facing the exhaust side.
- When installing the piston in the crankcase, the direction of travel arrow on the piston crown must point in the direction of travel.
- The code on the connecting-rod big end and connecting rod cap must be on the same side -A- .
- The direction of travel arrow is on the same side as the connecting rod code -A- on the piston shown. Fit the number on the connecting rod -A- facing the exhaust side.
- The direction of travel arrow must be pointing forwards (in direction of travel) when installed -inset- . The combustion chamber recess -1- on the DFI piston is facing the inner V (center of the engine) when installed -Up arrow- .
Information
Surface with cylinder number marking
- The piston connecting rods are cracked and only fit in one position (in conjunction with the matching numbers).
- Install con-rod code towards exhaust side -A- .
Information
The tightening specifications for the basic engine are stored centrally.
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or
> 1001IN TIGHTENING TORQUES, TIGHTENING SEQUENCES AND ASSEMBLY OVERVIEWS .
Tightening torques and assembly instructions for other assemblies (e.g. chassis, electrics, transmission or body) or for peripheral engine equipment can be found in the corresponding documents.
- Turn the engine in the engine support so that the crankshaft is at the bottom.
- Fit piston. To do this, turn the crankshaft with a wrench (a/f 27) until the corresponding crank pin is pointing straight down.
- Lightly oil the cylinder, piston and > 9784/1 - funnel (-1-
).
Oiling the piston funnel
1 Oil the inside of the funnel 2 Piston with connecting rod ready for installation - Align piston ring gaps (offset by 120°) and clamp piston rings together using > 9784/1 - funnel. Ensure that all piston rings are correctly tensioned by the special tool and check that they are not jammed. When doing this, slide the piston with connecting rod fitted into the funnel -2-
. The collar of the funnel must be facing the crankcase -1-
. Slide the piston into the funnel until the piston shank protrudes approx. one centimeter down out of the funnel. > Piston inserted in piston funnel
Inserting piston into piston funnel
Piston inserted in piston funnel
- Place piston onto cylinder from above and push into the cylinder using the handle of a hammer if necessary. When doing so, make sure that the direction of travel arrow is pointing forward. If you are using the > 9784/1 - funnel, position it flush on the crankcase -3-
. Check the position of the combustion chamber recess -1-
and the direction of travel arrow when doing this.
Fitting piston
- Push the piston downwards until the connecting rod bearing is sitting on the crank pin. Push it down further using the handle of a hammer if necessary - see figure-
. Do not use force. If the piston is jammed in the tool, oil the tool again if necessary or carefully loosen and turn the piston.
Pressing in piston
- Oil connecting-rod bearing shells and crank pins.
- Then fit the connecting rod cap with bearing shell (twist lock aligned) > Retaining lugs for connecting-rod bearings -B and C-
. The connecting rod numbers must be facing each other > View of matching numbers -A-
. Fit connecting rod bolts by hand.
Retaining lugs for connecting-rod bearings -B and C-
View of matching numbers -A-
- Fit the opposite piston (cylinders 1 and 4).
- Fit other pistons using the procedure described above.
- Turn the crankcase on the assembly support until the crankshaft is on top.
- Tighten connecting rod bolts that were replaced. Turn the crankshaft until the corresponding crank pin is pointing straight up.
- Once all pistons have been correctly fitted and secured, turn the crankshaft in a clockwise direction to check it using a ring wrench (a/f 27). Check for stiffness and irregularities while doing so. If the crankshaft cannot be turned or if it is very stiff, check whether the installation direction (arrow) of the pistons, the pistons and the cylinders (markings) and the connecting rod caps and connecting-rod big end all match.