Porshe 911 (997). Manual - part 49

4. Unscrew the central screw on the camshaft adjustment device. Position retaining tool 9685 on the

hexagon of the adapter and place the contact block as a counter on the fitting bore of the cylinder head
cover for the oil suction pump; if necessary, position the contact block by undoing and tightening the
screw. If the special tool cannot be positioned on the hexagon of the adapter in this way, the engine must
be turned further in the direction of rotation at the pulley of the crankshaft until the contact block comes
into contact with the central screw of the cylinder head cover, ready for unscrewing. Unscrew the central
screw.

5. Remove cylinder head cover. → 159119 Removing and installing cylinder head cover- chapter on

"removing".

6. Release the four Torx screws M6 x 16 on the sprocket of the respective exhaust camshaft. Do not

remove the sprocket.

Chain tensioner, cylinders 1 - 3

7. Remove chain tensioner for cylinders 1 - 3 or 4 - 6.

Chain tensioner, cylinders 4 - 6

8. Cylinder bank 4 - 6 Unscrew guide rail screw M6 on pulley side (hexagon socket a/f 5).

9. Turn the engine at the assembly support so that cylinder bank to be worked on stands vertically upwards.

10. Unscrew four Torx screws for exhaust camshaft sprocket. Lift timing chain off sprocket and remove

the sprocket. Lay timing chain on the mounting tab for the sprocket.

11. Remove the four camshaft thrust bearings and the guide rail. Unscrew eight Torx screws, six M6 x

35, two M6 x 40 (screws for guide rail). Lift the thrust bearing and the guide rail carefully off the
mounting points or timing chain.

12. Remove the camshafts. Remove exhaust camshaft, lift timing chain off the camshaft adjuster of the

inlet camshaft and remove the camshaft. Lay the timing chain in the chain housing in the cylinder
head.

Diagnostic system: reading out fault memory and activating systems

Removing camshafts - engine removed

353

Installing camshaft - engine removed

Installing camshafts, adjusting timing - engine removed

ATTENTION

Risk of damage due to particles of dirt.

Oil bores/oil ducts can become blocked up.

• 

→ When working on the engine, absolute cleanliness is essential.

→ Lay removed engine parts on a clean base and cover them without fail.

→ Use the cover for dust protection when fitting the engine NR.165 on the engine assembly support.

Identification of camshaft housing:

Identification of housings of camshafts:

Inlet camshaft:

• 

Thrust bearing:

 'E' and matching number on cylinder head/cylinder head cover

• 

Housing of bearing sleeve:

 only matching number

• 

Outlet camshaft:

• 

Thrust bearing on sprocket:

 '1A' and matching number on cylinder head/cylinder head cover

• 

2nd Thrust bearing:

 '2A' and matching number on cylinder head/cylinder head cover

• 

Diagnostic system: reading out fault memory and activating systems

 Installing camshaft - engine removed

354

Pulley fixed at 60° before TDC

1. To remove the play from the timing chain drive, turn the crankshaft by means of the pulley or

vibration balancerclockwise (running direction of engine to 60° before TDC : marking U6 on
pulley or vibration balancer coincides with fixing bore in crankcase

. Fix with locating pin

9595/1

.

Assembly of cylinder bank 4 - 6

2. Turn the engine on the assembly support until cylinder bank 4 - 6 stands vertically upwards.

3. Oil the bearing surfaces of the camshafts with new engine oil.

Inlet camshaft 4 - 6 in overlap

4. Insert inlet camshaft 4 - 6. Pull the timing chain out of the chain housing of the cylinder head with a

welding wire and position on the ring gear of the camshaft adjuster, at the same time inserting the
camshaft at overlapping TDC of cylinder 4 (the cams of cylinder 4 point towards the bulkhead of
the flat-base tappet housing -arrows- ).

Position of bearing sleeve for inlet camshaft

Note

Make sure that the bearing sleeve on the inlet camshaft is positioned correctly.

• 

Diagnostic system: reading out fault memory and activating systems

Installing camshafts, adjusting timing - engine removed

355

5. The bearing sleeve of the inlet camshaft must be positioned so that the centrally bored blind hole points

vertically upwards -arrow- (the rib of the cylinder head should also be at the centre in relation to the
bearing sleeve). In this position, the dowel pin in the bearing bore of the cylinder head will fit precisely
into the opposite off-centre blind hole bore. Any other bores are through-holes for guiding the oil.

Exhaust camshaft 4 - 6

6. Insert exhaust camshaft 4 - 6. Lay the timing chain on the flange for the sprocket, then insert the camshaft

at overlapping TDC of cylinder 4 (the outlet cams of cylinder 4 point towards the cams of the inlet
camshaft -arrows- ).

Position of sprocket 4 - 6 at 60° before TDC

7. Insert exhaust camshaft sprocket in the timing chain and position on camshaft flange. The four threaded

bores in the camshaft flange must be covered by the slots of the sprocket in the clockwise running
direction of the engine

 approximately half way -arrows- .

8. Oil the bearing surfaces of the camshafts with new engine oil.

Installation position of housing

Note

Diagnostic system: reading out fault memory and activating systems

Installing camshafts, adjusting timing - engine removed

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