Piston: Service and Repair
WM 131020 Removing and installing pistons
Tools
Technical values
Preliminary work
Information
- Dispose of fluid in accordance with legal requirements.
1. Remove engine. -> 100119 Removing and installing 3.6-litre DFI engine - section on "Removing" 100119 Removing and installing engine
2. Remove engine from transmission. -> 100127 Removing engine from transmission and mounting engine on transmission 100127 Removing engine from transmission and mounting engine on transmission
3. Secure engine on mounting bracket. -> 1001IN Supporting V6 3.6-litre DFI engine on mounting bracket 1001IN Supporting engine on mounting bracket
4. Remove engine retaining eyebolts at the front and rear. -> 1001IN Lifting V6 3.6-litre DFI engine with a workshop crane
5. Remove the engine wire harness. -> 97522100 Removing wire harness for engine (V6) 975219 Removing and installing wire harness for engine
6. Remove bar ignition modules. -> 282020 Removing and installing DFI bar ignition modules Service and Repair
7. Remove intake-air distributor. -> 244619 Removing and installing DFI intake-air distributor - section on "Removing" Service and Repair
8. Remove oil pan. -> 175019 Removing and installing oil pan on V6 DFI engines - section on "Removing" Service and Repair
9. Remove cylinder head.
9.1. Remove and dispose of cylinder head gasket.
9.2. Pull oil retaining valve -arrow- out using an M8 screw if necessary.
Oil retaining valve
Removing pistons
Information
- The pistons are removed in turn.
- The pistons, connecting rods and connecting rod caps are marked with a felt-tip pen so that they do not get mixed up.
- Pistons and connecting rods are laid on a clean surface in cylinder order.
- Con-rod bolts must always be replaced.
- If being reinstalled, used bearing shells must not be mixed up.
- Connecting rod bearing shells should always be replaced.
1. Remove piston.
Piston
1.1. Turn the crankshaft so that the crankshaft journal of the piston to be removed is standing straight up.
1.2. Remove connecting rod bolts. Remove connecting rod bearing caps and place on a clean surface, arranged according to cylinder.
1.3. Press the piston out of the cylinder from above (using the handle of a hammer for example) and support it from below with your hand.
1.4. Remove one piston after another and mark them according to the respective cylinder. Place the pistons on a clean surface.
1.5. Repeat this procedure for all pistons.
Installing pistons
1. Install piston.
Overview of piston/connecting rod
1.1. Pull dowel sleeve -arrow- out of the bore hole so that special tool funnel T10333 can be positioned flat on the cylinder block.
Dowel sleeve on cylinder block
1.2. Oil the piston well and insert it into the funnel.
1.3. Align all pistons so that the deep valve recesses -1 and 2- are facing the middle of the cylinder block and the arrows -3- on the pistons are facing the vibration damper.
Installation direction of pistons on V6 DFI engine
1.4. Position the piston funnel on the cylinder block and align it so that the high edge -arrow- is facing the middle of the cylinder block.
Positioning piston funnel on cylinder block
1.5. Slide piston fully into the cylinder bore.
1.5.1. Turn the crankshaft back and forth if necessary.
1.6. Insert dowel sleeves back into the bore holes -arrow-.
Information
- Oil the bearing shells and bearing with engine oil.
1.7. Oil connecting-rod bearing shells -5-.
Information
- The pistons must already be pre-fitted (pistons, piston rings, connecting rods and fastening material) before performing the next step.
- Note the association between the connecting-rod big end and the connecting-rod bearing cap.
- The retaining lugs of the connecting-rod bearing shells are always located on the same side in order to prevent the bearing shells from turning.
Retaining lugs
- The connecting-rod bearing cap and the connecting-rod big end have cast lugs which must lie above one another. These cast lugs lie on the same side as the twist lock (retaining lugs) of the connecting-rod bearing shells.
- The cast lugs, twist lock (retaining lugs) and the flat side of the piston crown are on the same side.
Component overview and allocation
- The flat side of the piston crown always points to the centre of the cylinder block.
- Refit pistons according to removal markings (if being reused).
- If new connecting-rod bearing shells are used, there will be a red marking on the upper shell and a yellow marking on the lower shell.
1.8. Assign connecting rod bearing caps correctly and screw in the connecting rod bolts -7- by hand. When doing so, make sure that the locking lugs on the bearing shells are aligned.
1.9. Carefully tap the connecting rod bearing caps -6- with a plastic hammer until they are seated correctly so that the tightening torque will be accurate.
1.10. Tighten all connecting rod bearing screws -7- to the specified tightening torque.
1.11. Turn the crankshaft several times to check that it turns smoothly.
1.12. Align the crankshaft so that the gap -arrow- on the drive plate for the inductive pickup is facing downwards (rough TDC presetting).
Setting of drive plate for inductive pickup
Subsequent work
1. Position engine to the compression TDC of cylinder 1.
TDC marking on pulley and housing cover
2. Install cylinder head.
Cylinder head
2.1. Thoroughly clean all sealing faces before assembly.
2.2. Cylinder head gasket must always be replaced.
2.3. Always observe tightening sequence (1-20) for cylinder-head screws -1-20- and tighten to the specified torque.
2.3.1. Tighten cylinder-head screws to an initial tightening torque of 15 Nm (11 ftlb.).
2.3.2. Tighten cylinder-head screws to 30 Nm (22 ftlb.).
2.3.3. Then tighten all cylinder-head screws a second time to 30 Nm (22 ftlb.).
2.3.4. And finally, tighten cylinder-head screws to a torque angle of 180°.
3. Fit timing chains.
Component overview of timing chains
3.1. Install chain tensioner. -> 153619 Removing and installing chain tensioner on V6 DFI engines Service and Repair
3.2. Install camshaft controllers. -> 158419 Removing and installing camshaft controller on V6 DFI engines Service and Repair
4. Check the timing.
5. Fit upper and lower timing-case cover. -> 153319 Removing and installing timing-case cover on V6 DFI engines
5.1. Fit lower timing-case cover.
Crankshaft joint flange
5.2. Fit upper timing-case cover.
Removing and installing vacuum pump
6. Install oil pan. -> 175019 Removing and installing oil pan on V6 DFI engines Service and Repair
Removing and installing upper timing chain housing cover
7. Install cylinder head cover. -> 158219 Removing and installing cylinder head cover on V6 DFI engines Service and Repair
Removing and installing valve cover seal
8. Install fuel distributor pipe and fuel injectors.
Fuel distributor pipe for cylinders
9. Install intake-air distributor. -> 244619 Removing and installing DFI intake-air distributor Service and Repair
10. Install guide tube for oil dipstick. Sealing ring must always be replaced. -> 171719 Removing and installing guide tube for oil dipstick on DFI engines Service and Repair
11. Install bar ignition modules. -> 282020 Removing and installing DFI bar ignition modules Service and Repair
Removing and fitting ignition coils and spark plugs
12. Fit engine wire harness. -> 97522100 Removing wire harness for engine (V6) 975219 Removing and installing wire harness for engine
13. Remove engine from the mounting bracket. -> 1001IN Supporting V6 3.6-litre DFI engine on mounting bracket 1001IN Supporting engine on mounting bracket
14. Mount the transmission. -> 100127 Removing engine from transmission and mounting engine on transmission 100127 Removing engine from transmission and mounting engine on transmission
15. Install the engine. -> 100119 Removing and installing 3.6-litre DFI engine 100119 Removing and installing engine
16. Perform a test drive and check for leaks and correct function.
16.1. Clean the engine and carry out a thorough check for leaks after the test drive.