Disassembling/Assembling Engine

Component overview - engine

Component overview - engine

Note: The overview graphics are shown schematically and may be different to how the components actually look.

Intake system, belt drive





^ 1 - Intake distributor
^ 2 - Belt drive
^ 3 - Belt guide and belt tensioner

Engine - lubrication





^ 4 - Oil pumps, heat exchanger, coolant guide housing
^ 5 - Oil pan, oil separator

Cylinder head, crankcase





^ 6 - Cylinder-head cover, camshafts, flat-base tappet housing, cylinder head
^ 7 - Cylinder head, flat-base tappets
^ 8 - Crankcase halves

Crank drive, pistons





^ 9 - Pistons, connecting rods
^ 10 - Bearing housing with intermediate shaft
^ 11 - Bearing housing halves with crankshaft

Disassembling engine down to crankcase

Disassembling engine down to crankcase

Caution: Risk of damage due to particles of dirt.
^ Danger of material damage due to blocked oil bores/oil ducts.

-> Absolute cleanliness is essential when working on the engine.
-> Lay removed engine parts on a clean base and make sure to cover them.
-> Use the cover for dust protection when fitting the engine NR.165 on the engine assembly support.

Warning: Coolant is corrosive and hazardous to health.
^ Risk of skin and eye irritation.

-> Wear protective gloves and goggles.
-> If you come into contact with coolant, wash off immediately with plenty of warm water.

Warning: Pentosin is hazardous to health
^ Danger of material damage and injury

-> Wear protective gloves and goggles.
-> If the eyes or skin come into contact with the fluid, wash immediately with water.
-> Collect emerging Pentosin. Clean hoses which come into contact with Pentosin thoroughly.
-> Use caps to protect the wiring against soiling and damage.

Note: The bearing housing remains screwed to the retaining device when the bearing housing and intermediate shaft are disassembled.

1. Engine support 9589 must be secured to the crankcase using special tool mounting elements 9590. Refit engine with support on the engine assembly support.





2. Drain engine oil. Unscrew the oil drain plug (hexagon socket a/f 8).





3. Remove engine carrier. Unscrew 4 M10 collar nuts and 1 M6 x 20 Torx screw.





4. Undo 3 M8 x 12 fastening screws on the belt pulley for the servo pump (do not remove).
5. Remove drive belt. Mark the running direction with a colored pen, turn the tensioning roller (a/f 24) clockwise, hold still and simultaneously remove the belt from the drive pulleys. Check the belt for damage, replace if necessary.





6. Only for Tiptronic: remove guide for drive belt, to do this, unscrew two M6 x 20 Torx screws.
7. Unclip hose assembly on the intake distributor, cylinder side 1 - 3:





8. Unplug crankcase ventilation line on pre-separator, cylinder 4-6.





9. Remove shields for ignition coils on the left and the right, unscrew 2 M6 x 16 fastening screws.





10. Disconnect electric plug connections (engine wire harness) on engine and unclip wire harness on the fuel collection pipes.





^ Three injection valve plugs per cylinder side -1-
^ Three ignition coil plugs per cylinder side -2-
^ Two plugs for camshaft adjustment hydraulic valves, two for valve lift adjustment hydraulic valves -3-
^ Plug for engine coolant temperature sensor, two plugs for oil pressure sensor on cylinder head cover 4 - 6 -4-
^ Two hall sender connectors
^ Plugs for speed sender
^ Plug for electric switch-over valve (intake distributor 1-3)
^ Ground cable for front face of cylinder 4-6 (one M6 x 12 Torx screw)
^ Plug for engine compartment temperature sensor (intake distributor 4-6)

11. Unclip fuel ring pipe on the engine eyelet and unscrew two M6 x 16 Torx screws, remove engine eyelet.
12. Detach holder for the throttle body on the servo pump. To do so, unscrew an M6 hexagon nut. Unplug cable plug for potentiometer and line for crankcase venting.
13. Undo holder for servo supply tank on intake distributor 4-6.
14. Only for 3.61 engine: Remove the relevant six M6 x 35 (micro-self-locking) fastening screws for the intake distributor on the intake pipe supports on the left and the right. Pull off one vacuum line and remove the intake distributor completely.





15. Only for 3.61 engine: Remove intake pipe support. Unscrew four M6 x 35 screws, unscrew one M6 x 12 screw for ground strap on cylinder bank 4 - 6. Take off intake pipe support, seal intake openings on cylinder head (e.g. with adhesive tape).





16. Only for 3.81 engine: Unscrew the four M6 x 35 Torx screws. Completely remove the intake distributor. Seal intake openings on cylinder head (e.g. with adhesive tape).





17. Remove belt pulley from servo pump. Unscrew three fastening screws and remove belt pulley.
18. Remove generator. Undo the fastening screw on the deflection roller -1- and unscrew approx. three turns. Using an aluminum mandrel, tap lightly on the screw head to undo the pilot bushing in the generator swivel arm. Unscrew the screw and remove with the deflection roller. Unscrew the second screw -2- and carefully take out the generator.





19. Lift the generator out of the bracket and disconnect the two electric connecting lines -Arrows-.





20. Remove mount for the coolant vent line. Unscrew one M6 x 16 (micro-self-locking), remove mount, replace screw.
21. Unplug all vent lines for oil mist collector.





22. Unscrew the two M6 x 20 Torx screws on the 3.8 l oil mist collector mount and pull off collector. Replace two O-rings during installation. The screws tighten the secondary air line on cylinder head 4-6 at the same time.





23. The oil mist collector on a 3.6 l engine is removed in the same way as the 996 unit.





24. Unscrew one fastening screw for the wire harness guide on the bracket for the secondary air pump -1-and unclip the guide -2- on the bracket -Arrow-.





25. Remove the secondary air pump. Unplug cable plug, unscrew three M6 x 20 Torx screws on the bracket -1- and completely take out the pump with bracket and line. Use new seals when installing.





26. Release the wire harness on the holder before the heat exchanger. Then unscrew the plastic holder.





27. Undo the wire harness on the center of engine (connections to starter) -Arrow- and unclip on the heat exchanger -1-. Unplug cable plug for knock sensors -2- and oil-level sensor. Then completely remove the engine wire harness.





28. Remove the oil filler neck. Unscrew 2 M6 x 16 Torx screws (micro-self-locking), pull out oil filler neck, check the O-ring and replace if necessary.





29. Remove oil/water heat exchanger. Unscrew the four inner M6 x 16 Torx screws, take off heat exchanger. Replace O-rings during installation.
30. Remove hydraulic pump with servo line and supply tank. Undo servo line (a/f 16) -1-, counter on large hexagon when doing this (a/f 27). Unscrew four Torx screws (3 M8 x 30 at the front -Arrows-, one M8 x 12 at the back), take the servo pump with line and supply tank out of the bracket.





31. Remove bracket for servo pump. Unscrew 4 M8 x 35 Torx screws, remove bracket.





32. Remove one M8 x 60 screw for deflection roller -1- and six M6 x 20 Torx screws for closure cap -2- with bleeder lines for coolant system.





33. Only in manual transmissions: Remove the starter. Unscrew two M10 x 35 Torx screws -1-, take off starter -2-.





34. Remove oil-level sensor (a/f 19), remove knock sensor, to do this, mark the installation position with a paint marker, then unscrew one M8 x 35 Torx screw each and take off the sensors.
35. Remove canister for additional volumes of crankcase venting to the cylinder heads 1-3 and 4-6. Unscrew two M6 x 25 Torx screws each, take off canister. Use new O-rings when installing.
36. Remove the holder for the main muffler on the left and right. Unscrew two M8 x 30 Torx screws each on the intake side and two M8 x 25 each on the exhaust side and take off mount.





37. Remove mount and sealing cap for hydraulic valves for camshaft adjustment -2-. Unscrew two M6 x 20 Torx screws each, take off mount and sealing cap.





38. Remove three ignition coils per cylinder side -1-. Unscrew 12 M6 x 25 Torx screws, pull off ignition coils.
39. Remove six spark plugs. Use only approved tool spark plug socket wrench 14 from Snap-On (in case ceramic body breaks).
40. Pull off hydraulic valves for camshaft and valve lift adjustment. To do this, the special tool relay puller 9235 can be used. Pull the oil strainer for the camshaft adjustment valve out of the valve bore -1- with a magnet, replace the oil strainer.





41. Remove the exhaust manifold. Unscrew six M8 x 28 screws each, remove manifold and seal.
42. Remove coolant pipe for heating. Side 1-3: unscrew two M6 x 12 Torx screws, side 4-6: unscrew three M6 x 12 Torx screws, remove coolant pipe.
43. Remove oil pressure sensor on cylinder head cover 4 - 6 (a/f 19).
44. Remove the mount for the air conditioning compressor. Unscrew two M8 fastening screws, and remove bracket.
45. Remove hall sender. Unscrew 1 M6 x 16 pan-head screw (hexagon socket a/f 5, micro-self-locking) and pull off hall sender, replace screws.
46. Remove knock sensors. Mark installation position (plug connection) with a paint marker, unscrew one M8 x 35 Torx screw each, pull sensors out of crankcase.
47. Remove speed sender, unscrew one M6 x 16 pan-head screw (hexagon socket a/f 5, micro-self-locking), remove sender, replace screw.
48. Pull coolant hose assembly out of plastic holder on crankcase. Undo spring band clamps on water pump and thermostat and take off hoses. Remove mount, to do this, unscrew one M6 x 16 Torx screw (micro-self-locking), replace screw.





49. Remove all plastic closure caps on the cylinder heads, and replace closure caps.
50. Turn engine on the belt pulley of the crankshaft clockwise to the overlapping TDC of cylinder bank 1 - 3. To check cylinder 1-3, insert the special tool adjusting gauge 9686 in the camshaft slots. If the gauge cannot be inserted, the engine must be turned an additional 360°.
51. Remove oil extraction pump cylinders 1-3. Unscrew four M6 x 20 Torx screws (micro-self-locking), carefully pull the oil extraction pumps out of the fitting bore. Replace screws.
52. Remove tandem pump on cylinder side 4-6. Unscrew four M6 x 30 fastening screws -1-, pull vacuum line -2- out of the connection fitting on the pump, take out the pump. Replace O-rings.





Note: The central screws of the camshaft adjustment elements must be undone before removing the cylinder head cover.

53. The central screws of the camshaft adjuster must be undone before removing the cylinder head covers. To do this, place special tool retaining tool 9685 on the large hexagon of the central screw and cylinder head cover and undo the screws.

Removing camshafts, cylinder bank 1-3:

54. Remove cylinder head cover 1-3.
55. Remove all chain tensioners and replace aluminum sealing rings during installation.
56. Remove upper M6 screw (hexagon socket a/f 5) for guide rail cylinder 4-6.
57. Remove camshaft side 1-3.

Caution: Interchanged or dirty bucket tappets.
^ Damage to engine components.

-> The components have been run in the fitting bores in the housing, therefore do not interchange them.
-> Absolute cleanliness is essential.

58. Remove the flat-based tappets. Pull the components out with a strong magnet out of the flat-base tappets housing. To avoid confusing the individual flat-based tappets, lay them on a labelled, clean surface (see example) and cover.





59. Place engine on the belt pulley of the crankshaft clockwise to the overlapping TDC of cylinder bank 4-6. To do this, turn the engine a further 360° clockwise. To check cylinder 4-6, insert the special tool adjusting gauge 9686 in the camshaft slots.

Removing camshafts, cylinder bank 4-6:
60. Remove cylinder head cover 4-6.
61. Unscrew the top M6 guide rail screw (hexagon socket a/f 5) on cylinder 4-6.
62. Remove camshaft side 4-6.
63. Remove flat-base tappet housing. Unscrew 11 M6 x 35 Torx screws per housing, one 1/4-inch E10 socket is necessary for this. Take flat-base tappet housing out of the cylinder head. It is absolutely necessary to replace O-rings for spark-plug recesses when installing.
64. Unscrew the top M6 guide rail screw (hexagon socket a/f 5) on cylinder 1-3.
65. Unscrew four M6 x 30 Torx screws -Pos 1 - 4- per cylinder bank.





66. Remove cylinder head. Undo and unscrew 12 M10 x 230 Torx screws from inside to outside on each cylinder head. Lift the cylinder header and seal off the crankcase.
67. Remove all carbon deposits and other residues on all six pistons with a brass brush, which will make the engraved markings -Arrow facing flywheel side- visible. Before removing, number and mark the pistons in the installation position.





68. Unscrew M27 aluminum screw plug for the assembly bore (piston pin).
69. Remove coolant closure cap (with connection for coolant ventilation). Unscrew six M6 x 20 inner Torx screws, remove cover, and replace the seal.
70. Remove connection supports for coolant hose on the top of the coolant guide housing. Unscrew two M6 x 20 Torx screws and remove cover.
71. Remove coolant temperature sensor (a/f 22).
72. Remove coolant closure cap at the bottom of the coolant guide housing. Unscrew four M6 x 20 Torx screws and remove cover.
73. Remove coolant pump. Unscrew seven hexagon-head bolts (two M6 x 30 and five M6 x 25) and remove pump.
74. Remove thermostat housing. Unscrew four M6 x 20 Torx screws and remove housing, including thermostat.
75. Remove coolant guide housing and oil pump. Unscrew ten Torx screws, namely eight M6 x 20 and two M6 x 70, and carefully lift off housing with seal (press lightly with an assembly lever if necessary). Pull out the driver for the oil pump. Remove the drive belt guide in Tiptronic vehicles.





76. Remove lower M6 guide and tensioning rail screws (hexagon socket a/f 5), remove the guide and tensioning rails from the chain spaces.
77. Remove oil filter with special tool release key 9204.
78. Unscrew 13 M6 x 20 Torx screws on the oil pan cover. Tap cover gently on the sides using a plastic hammer, then carefully lift it at the leverage bar -see Figure- using a plastic-coated mounting lever and remove the oil pan.





79. Remove air/oil separator (swirl pots) and oil suction pipe. To remove each separator, unscrew two M6 x 20 Torx screws and pull out the separator. Unscrew two M6 x 20 Torx screws on the oil suction pipe and remove the oil suction pipe.





80. Remove bearing cover for intermediate shaft.
81. Undo M16 x 1.5 x 60 hexagon-head bolt for belt pulley or vibration damper with special tool socket wrench insert 9594, while countering with special tool retaining device 9593 -> Screw on belt pulley - 3.6 l engine or holding wrench 9732. Do not unscrew the screw.





Assembling engine - starting with the crankcase

Assembling engine - starting with the crankcase

Caution: Risk of damage due to particles of dirt.
^ Danger of material damage due to blocked oil bores/oil ducts.

-> Absolute cleanliness is essential when working on the engine.
-> Lay removed engine parts on a clean base and make sure to cover them.
-> Use the cover for dust protection when fitting the engine NR.165 on the engine assembly support.

Note: All O-rings and seals (shaft seals), micro-encapsulated, coated screws or lock nuts must be replaced.

The engine is assembled in reverse order to the disassembly. Components that are not replaced must be cleaned.

Markings on crankcase:

Engine number





Cylinder arrangement





Note: Replace M6 micro-encapsulated screws and M8 hexagon collar nut for intermediate shaft bearing cap.

1. Fit bearing cover for intermediate shaft with new sealing ring.
2. Install guide rail for cylinder 4-6. Insert guide rail with slot into the crankcase. Fit screw with new O-ring, grease the O-ring with Optimol MP3. -> Tightening torque: 10 Nm (7.5 ftlb.)
3. Install tensioning rail for cylinder 4-6. Fit screw with new O-ring, grease the O-ring with Optimol MP3. -> Tightening torque: 10 Nm (7.5 ftlb.)
4. Remove auxiliary screw for gear carrier.
5. Fit air/oil separator (swirl pots) and suction pipe. Replace two micro-self-locking M6 x 20 Torx screws and O-rings for the suction tube. -> Tightening torque: 10 Nm (7.5 ftlb.)





6. Install oil pan. Apply a bead of sealant, Loctite 5900, to the cleaned and greased oil pan and secure with 13 M6 x 20 Torx screws from the inside out. -> Tightening torque: 10 Nm (7.5 ftlb.)
7. Fit oil filter, grease new O-ring with Optimol MP3. -> Tightening torque: 25 Nm (19 ftlb.)
8. Fit thermostat with new seal. Tighten four M6 x 20 Torx screws. -> Tightening torque: 10 Nm (7.5 ftlb.)
9. Fit tensioning rail for cylinder 1-3. Fit screw with new O-ring, grease the O-ring with Optimol MP3. -> Tightening torque: 10 Nm (7.5 ftlb.)

Note: Replace O-rings for the oil pump and sealing rings for coolant guide housing.

10. Install coolant pump. Position pump with the new seal (a single part in conjunction with the seal for the oil pump housing). Position and tighten seven M6 Torx screws (two M6 x 30 screws on the dowel sleeves, five M6 x 25 screws). -> Tightening torque: 10 Nm (7.5 ftlb.)
11. Remove centering mandrel for intermediate shaft. Position oil pump with new seal and two new O-rings. Grease the O-rings with Optimol MP3. Pull timing chain 4-6 outward so that the intermediate shaft is centered. Align driver for the oil pump and then push the housing together with the oil pump into the bearing seat. It is advisable to get a second person to assist to make the assembly easier.





12. Coat the thread of two M6 x 70 Torx screws with Loctite 574 and position on oil pump housing. Position the remaining eight M6 x 20 Torx screws, tighten all screws. -> Tightening torque: 10 Nm (7.5 ftlb.)
13. Fit coolant connection piece with new seal and two M6 x 20 Torx socket screws. -> Tightening torque: 10 Nm (7.5 ftlb.)
14. Fit coolant breather adapter with new seal and six M6 x 20 Torx socket screws. -> Tightening torque: 10 Nm (7.5 ftlb.)
15. Fit pulse sender with new, micro-self-locking M6 cheese head bolt. -> Tightening torque: 10 Nm (7.5 ftlb.)
16. Fit belt pulley/vibration balancer.
17. Fix timing chains with chain sprockets, e.g. with the old O-rings from the oil suction pumps.





18. Install temperature sensor for coolant (M14 a/f 22). -> Tightening torque: 25 Nm (19 ftlb.)± 5 Nm (± 3.5 ftlb.)

Note: Cylinder-head gaskets are identical parts, lay them down with the TOP identification facing upwards.

19. Fit new cylinder-head gaskets, the TOP marking is legible from above.
20. Fit cylinder heads. Observe tightening sequence and tightening specification of cylinder-head screws. -> Initial tightening: 30 Nm (22 ftlb.), loosen all screws, 2nd initial tightening: 20 Nm (15 ftlb.); -> 2 x torque angle (final tightening): 70°





21. Tighten external M6 (Torx) cylinder-head screws. -> Tightening torque: 13 Nm (9.5 ftlb.)





22. Install guide rail for cylinder 1-3. The slot is positioned in the crankcase, the sealing lip towards the outside. Fit screw with new O-ring, grease the O-ring with Optimol MP3. -> Tightening torque: 10 Nm (7.5 ftlb.)

The threaded pin for guide rail 4-6 (belt pulley side) on the cylinder head is inserted only after the timing chain has been fitted on the camshaft wheels.

Note: The O-rings for the spark-plug recesses must be replaced.

23. Insert three new O-rings in the spark-plug recesses, lightly coat with high pressure grease. Fit flat-base tappet housing with 11 M6 x 35 Torx screws and tighten screws from the inside out. -> Tightening torque: 10 Nm (7.5 ftlb.)





Note: Re-insert flat-base tappets in the fitted bores in which they were positioned before the disassembly. The flat-base tappets have been run in the fitting bores in the housing and therefore may not be switched.

24. Coat flat-base tappets with new engine oil and insert in the fitted bores in the flat-base tappet housing (operating plunger with dowel pin on the inlet side).





25. Install camshafts and adjust controls as for engine type M96/03-3, 6l as of model year 2002.
26. Fit cylinder head cover. Eight new, coated screws -1- must be used for the threaded joints on the camshaft bearing surfaces. For each one, tighten 20 M6 fastening screws according to the tightening sequence. Of each of the sets of 20 screws, only position two screws on the oil suction side (or tandem pump) and only perform the final tightening after fitting the pumps. -> Tightening torque: 13 Nm (9.5 ftlb.)





Sealant application on cylinder head cover





Tightening sequence for cylinder head cover





27. Install tandem pump and oil suction pump with new, micro-self-locking screws and new O-rings. Fit the line on the tandem pump with two new O-rings. Grease O-rings with Optimol MP3. -> Tightening torque: 10 Nm (7.5 ftlb.)

Install engine accessories in the reverse sequence to that in which they were removed. Some additional instructions follow.

- Install six spark plugs: -> Tightening torque: 30 Nm (22 ftlb.); -> Tightening torque: 25 Nm (19 ftlb.)
- Six ignition coils: tighten two M6 Torx socket screws for each of them. -> Tightening torque: 10 Nm (7.5 ftlb.)
- Hall sender: use two new M6 micro-self-locking screws. -> Tightening torque: 10 Nm (7.5 ftlb.)± 0.5 Nm (± 0.5 ftlb.)
- Exhaust manifold: use new M8 x 28 hexagon-head bolts. -> Tightening torque: 23 Nm (17 ftlb.)
- Support for coolant ventilation: replace one M6 x 16 (micro-self-locking) screw. -> Tightening torque: 10 Nm (7.5 ftlb.)
- Fit oil separator with new O-rings. Screw in M6 x 20 fastening screws on support bracket (3.8 l engine) or crankcase (3.6 l engine). -> Tightening torque: 10 Nm (7.5 ftlb.)
- Install secondary air pump three M6 x 20 Torx screws on the bracket -> Tightening torque: 10 Nm (7.5 ftlb.)
- Intake pipe support in the 3.6 l: install with four M6 x 35 Torx screws and new seals. -> Tightening torque: 10 Nm (7.5 ftlb.)
- Intake-air distributor in the 3.6 l: install with six M6 x 35 Torx screws and new moulded seals on intake pipe support. -> Tightening torque: 10 Nm (7.5 ftlb.)
- Intake-air distributor in the 3.8 1: four M6 Torx screws. -> Tightening torque: 10 Nm (7.5 ftlb.)
- Install generator: tighten M8 hexagon nut for B+ cable to the specified torque. -> Tightening torque: 15 Nm (11 ftlb.).

Assembling engine, subsequent work

Assembling engine, touching up
1. Fit flywheel.
2. Fit clutch.

or

3. Fit converter housing.
4. Fit drive plate for converter.
5. Mount transmission.
6. Install engine.