Porshe 911 (997). Manual - part 80

Removing cylinder head

Removing cylinder head

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.

Cylinder head 1-3:

Guide rail screw for cylinders 1-3

1. Unscrew M6 threaded bolt (hexagon socket) for guide rail (flywheel side) -1- .

External cylinder head screwed connection

2. Unscrew four Torx screws with M6 x 30 captive washers (10.9) -1-4- at the chain slot. Use of a magnetic

bit is recommended so that the screw to be fitted in the slot -item 4- cannot fall into the crankcase.

3. Loosen and unscrew 12 M10 Torx cylinder-head screws from outside to inside.

4. Carefully lift off the cylinder head and remove the old cylinder-head gasket.

5. Carefully clean the sealing faces on the cylinder head and crankcase (e.g. using a nylon brush and a clean,

lint-free cloth soaked in acetone). Check the sealing face from cylinder head to crankcase for damage and

Diagnostic system: reading out fault memory and activating systems

 Removing cylinder head

477

cracks, and rework the flat surface if necessary.

The removal of cylinder head 4-6 is the same as for side 1-3 with the following change

–  The threaded bolt for guide rail 4-6 on the cylinder head (belt pulley side) -1- is removed even before

the camshaft timing gears are removed.

Guide rail screw for cylinders 4-6

Installing cylinder head

Installing cylinder head

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.

Fitting cylinder head side 1 - 3:

1. Turn the crankcase at the assembly support in such a way that side 1-3 stands vertically upwards.

2. Fit new cylinder-head gasket. The inscription 'OBEN/TOP' must be clearly

visible.

3. Carefully position the cylinder head on the crankcase. Pay attention to the dowel sleeves.

Diagnostic system: reading out fault memory and activating systems

Removing cylinder head

478

Tightening sequence for cylinder-head screws

4. Screw in 12 M10 Torx screws evenly and tighten according to the prescribed tightening sequence -1-12- .

→ Initial tightening: 22 ftlb.

 , loosen all screws in reverse tightening sequence; → Initial tightening: 15

ftlb.

 ; → Final tightening, 2 x torque angle: 70 °

External cylinder head screwed connection

5. Screw in and tighten four Torx screws with M6 x 30 captive washers (10.9) -1-4- at the chain slot. Use of

a magnetic bit is recommended so that the screw to be fitted in the slot -item 4- cannot fall into the
crankcase. → Tightening torque: 9.5 ftlb.

Guide rail screw for cylinders 1-3

6. Fit threaded bolt for guide rail -1- with a new O-ring at the cylinder head. → Tightening torque: 7.5 ftlb.

The installation of cylinder head side 4 -6 is carried out in the same way as the assembly sequence for
side 1-3 with the following change:

Diagnostic system: reading out fault memory and activating systems

Installing cylinder head

479

Guide rail screw for cylinders 4-6

–  The threaded bolt for guide rail 4-6 on the cylinder head (belt pulley side) -1- is inserted only after

the timing chain has been fitted on the camshaft timing gears.

Subsequent work for installing cylinder head

Subsequent work for installing cylinder head

O-rings on spark-plug recess seal

1. Insert three new O-rings at the spark-plug recesses -arrows- , lightly coat with high-pressure

grease.

Flat-base tappet housing bolts

Diagnostic system: reading out fault memory and activating systems

 Subsequent work for installing cylinder head

480