Part 1
WM 1001Z1 Disassembling engine
Tools
Preliminary work
1. Remove the engine. -> 100119 Removing and installing engine 100119 Removing and installing engine
2. Remove the transmission. -> 343527 Removing and mounting transmission 343555 Replacing transmission
3. Secure engine on assembly support. -> 1001IN Securing engine on assembly support (mounting bracket) 1001IN Securing engine on assembly support (mounting bracket)
4. Drain engine oil. For details, see -> 170117 Draining and filling engine oil (changing engine oil) Removal and Replacement
Disassembling engine
NOTICE
Interchanged or dirty bucket tappets
- Scoring on cylinder head
-> Since the bucket tappets have been run in in the fitting bores, do not interchange them.
-> Absolute cleanliness is essential.
Information
Please observe the following for the V6 =>
- The repair concepts for the V6 are the same as for the V8.
- The special features and component deviations are listed and shown in -> 1001IN Tightening torques, tightening sequences and assembly overviews [1][2]Specifications.
- More significant deviations are shown in separate descriptions.
- If no special features are specifically highlighted, the assembly and adjustment instructions for the V8 apply.
Information
- Particular care and attention must be paid to the combined V6 oil pump balance shaft module during disassembly and assembly work. This is completely different from the V8 oil pump concept.
- The V6 oil pump balance shaft module with the balance weight is installed at a defined position with respect to the crankshaft.
- The balance shaft in the V6 oil pump balance shaft module is fixed to the crankshaft. Non-observance of this requirement results in strong vibrations in the engine.
- For details, see -> 172019 Removing and installing oil pump Removal and Replacement.
Information
Have a collection pan and some cloths ready before starting work on the engine block. Close off open hoses immediately after opening them using suitable stoppers. Residual fluid can leak out.
Information
For many components, it is only necessary to partially disassemble the engine. The extent of disassembly depends on the damage and scope of repairs to be carried out.
When replacing the cylinder head gasket, many components, such as the vacuum pump, injectors and exhaust manifolds, remain on the cylinder head. In this case, the cylinder head can be lifted from the crankcase with all components intact.
1. Remove drive belt. -> 137819 Removing and installing drive belt 137819 Removing and installing drive belt
2. Remove power-steering pump and air-conditioning compressor if necessary.
3. On 4WD engines with all-wheel drive, remove the front-axle final drive and the cross-shaft engine carrier. For a detailed description, see -> 398819 Removing and installing all-wheel final drive
3.1. First remove the cross-shaft engine carrier and cross shaft and carefully pull them out of the crankcase.
3.2. Remove front-axle final drive.
4. Remove spark plugs. -> 287020 Removing and fitting spark plugs Service and Repair
5. Remove tank vent line -3- and engine ventilation lines -1 and 2-.
Ventilation on naturally aspirated engines
6. Remove oil mist separator. -> 105519 Removing and installing oil mist separator Service and Repair
7. Remove intake-air distributor. -> 244619 Removing and installing intake-air distributor Service and Repair
8. Remove fuel distributor pipe. -> 243019 Removing and installing fuel distributor pipe Removal and Replacement
9. Remove high-pressure pump at cylinder 8. -> 246319 Removing and installing high-pressure pump Service and Repair
10. Remove vacuum pump at cylinder 4. To do this, loosen the three screws. => Vacuum pump
Vacuum pump
11. Remove low-pressure line -4- at the cylinder head.
High-pressure pump, naturally aspirated engine
12. Detach and remove the coolant hose assembly -5-. Remove coolant pipe -4-.
Coolant return on naturally aspirated engine
13. Remove water pump. -> 195019 Removing and installing coolant pump Service and Repair
Coolant pump
14. Remove vent line.
14.1. Unscrew fastening screws -1-.
14.2. Unclip vent line -2- from the cable duct and remove it -arrow-.
Removing vent line
15. Remove the generator. Expose the peripheral equipment and unscrew the generator.
15.1. Remove support bracket (crash support) -10- from the generator (two screws) -9-.
Auxiliary units
15.2. Remove fastening screws on the generator -2 and 3-.
Generator
15.3. Carefully remove the generator and disconnect B+ cable. To do this, remove nut on the rear of the generator.
16. Disconnect the cable plug at the coolant regulator (thermostat insert) using pointed-nose pliers. Remove engine wire harness. For details, see -> 975219 Removing and installing wire harness for engine 975219 Removing and installing wire harness for engine
16.1. Unscrew fastening screws.
16.2. Lift engine wire harness up and out -arrow-
Loosening engine wire harness at the engine housing
17. Disconnect coolant pipe -1- at the collection pipe. To do this, remove the screws -2-.
Coolant guide
18. Remove thermostat housing.
18.1. Pull out thermostat insert (coolant regulator) -5-. Pull out thermostat insert (coolant regulator) using a solid electric cable. For a detailed description of how to remove the thermostat insert, see -> 195819 Removing and installing coolant regulator Service and Repair.
18.2. Detach thermostat housing and remove with the coolant pipe fitted.
Thermostat housing and coolant regulator
19. Remove metal pipe for coolant supply -2-. Remove coolant hoses and metal pipe -5 and 6-.
Coolant supply on naturally aspirated engine
20. Remove high-pressure line -2-. To do this, remove union nut -5-.
High-pressure pump, naturally aspirated engine
21. Remove the starter -1-. To do this, remove the screws -2-.
Starter
22. Remove exhaust manifold on both sides on 2WD engine. => Exhaust manifold seal and mount on naturally aspirated engine, cylinders 1 to 4 => Exhaust manifold seal and mount on naturally aspirated engine, cylinders 5 to 8
Exhaust manifold seal and mount on naturally aspirated engine, cylinders 1 to 4
Exhaust manifold seal and mount on naturally aspirated engine, cylinders 5 to 8
23. Remove engine carrier with engine mountings on both sides on 2WD engine. => Left bracket for auxiliary units and 2WD engine mounting => Engine mounting, right
Left bracket for auxiliary units and 2WD engine mounting
Engine mounting, right
24. On 4WD vehicles, remove cross shaft cover -1- on both sides.
Cross shaft cover
24.1. Unscrew fastening screws -arrows- on both sides.
24.2. Remove one cross shaft cover -1-.
24.3. The second cross shaft cover will be removed with the cross shaft pipe -1-.
Cross shaft pipe with cover
It does not matter whether the cross shaft pipe -1- is removed with the left or right cover.
24.4. Remove housing sealant -2- under both cross shaft covers.
25. Remove belt tensioner and deflection rollers. To do this, carefully lever off the covers on the rollers and unscrew the components. -1, 2, 3, 4-
Belt drive
26. Unscrew oil pressure sensor -3- with adapter -1- from the crankcase. To do this, remove the screws -4-.
Oil pressure sensor and oil pressure measuring point
27. Remove both cylinder head covers (valve covers). => Bar ignition modules and valve covers, cylinder row 1 to 4 => Bar ignition modules and valve covers, cylinder bank 5 to 8
Bar ignition modules and valve covers, cylinder row 1 to 4
Bar ignition modules and valve covers, cylinder bank 5 to 8
WARNING
Objects or loads falling down
- Risk of squashing or crushing
-> Secure components to prevent them from falling down.
Information
Support the engine at the oil pan or engine carrier using suitable lifting equipment and a wide wooden block.
28. Loosen screw on vibration balancer by two turns -4 and 3-. To do this, hold a brace brace 9679/1 at the vibration balancer with the help of a second worker. Support the brace on the floor if necessary. A very high torque is required to loosen the screw (more than 800 Nm/592 ftlb.). A long 3/4-inch tool is the best tool to use for this. The engine should be supported to prevent it from tipping over.
Supporting engine (illustration shows V8 4.5-litre engine supported on assembly support)
Pulleys
29. Turn the crankshaft at the vibration balancer so that the staking bore of the vibration balancer is located approx. 45° degrees in front of the lower staking point on the timing-case cover. => Staking bore 45 degrees before TDC
Staking bore 45 degrees before TDC
30. Remove chain tensioner for timing chain from the timing-case cover. -5-
Chain tensioner
31. Loosen camshaft controller and sprockets on the four camshafts by 2 turns. Always counter at the hexagon on the components when doing this. => Sprocket => Camshaft controller
Sprocket
Camshaft controller
32. Remove vibration balancer.
33. Turn the engine around. The oil pan must be facing upwards.
34. Unscrew oil pan -1-. To do this, remove all the screws -5-. The seal must be replaced.
