Opel Zafira B MPV 2006 Owners Workshop Manual page 118

20•14 1.9 litre DOHC diesel engine in-car repair procedures
12.19 Cylinder head gasket thickness
identification hole (arrowed)
are damaged easily. Also, make sure that
the carbon is not allowed to enter the oil and
water passages - this is particularly important
for the lubrication system, as carbon could
block the oil supply to any of the engine's
components. Using adhesive tape and paper,
seal the water, oil and bolt holes in the cylinder
block/crankcase. To prevent carbon entering
the gap between the pistons and bores, smear
a little grease in the gap. After cleaning each
piston, use a small brush to remove all traces
of grease and carbon from the gap, then wipe
away the remainder with a clean rag. Clean all
the pistons in the same way.
15 Check the mating surfaces of the cylinder
block/crankcase and the cylinder head for
nicks, deep scratches and other damage. If
slight, they may be removed carefully with a
file, but if excessive, machining may be the
only alternative to renewal.
16 Ensure that the cylinder head bolt holes
in the crankcase are clean and free of oil.
Syringe or soak up any oil left in the bolt holes.
This is most important in order that the correct
bolt tightening torque can be applied and
to prevent the possibility of the block being
cracked by hydraulic pressure when the bolts
are tightened.
17 The cylinder head bolts must be discarded
and renewed, regardless of their apparent
condition.
12.21 Using a dial test indicator to
measure piston protrusion
18 If warpage of the cylinder head gasket
surface is suspected, use a straight-edge to
check it for distortion. Refer to Part E of this
Chapter if necessary.
19 On this engine, the cylinder head-to-
piston clearance is controlled by fitting
different thickness head gaskets. The gasket
thickness can be determined by looking at the
holes stamped on the edge of the gasket (see
illustration).
Number of holes Gasket thickness
No holes 0.77 to 0.87 mm
One hole 0.87 to 0.97 mm
Two holes 0.97 to 1.07 mm
The correct thickness of gasket required is
selected by measuring the piston protrusions
as follows.
20 Mount a dial test indicator securely on the
block so that its pointer can be easily pivoted
between the piston crown and block mating
surface. Turn the crankshaft to bring No 1 piston
roughly to the TDC position. Move the dial test
indicator probe over and in contact with No 1
piston. Turn the crankshaft back-and-forth
slightly until the highest reading is shown on the
gauge, indicating that the piston is at TDC.
21 Zero the dial test indicator on the gasket
surface of the cylinder block then carefully
move the indicator over No 1 piston. Measure
its protrusion at the highest point between the
valve cut-outs, and then again at its highest
point between the valve cut-outs at 90° to the
first measurement (see illustration). Repeat
this procedure with No 4 piston.
22 Rotate the crankshaft half a turn (180°)
to bring No 2 and 3 pistons to TDC. Ensure
the crankshaft is accurately positioned then
measure the protrusions of No 2 and 3 pistons
at the specified points. Once all pistons have
been measured, rotate the crankshaft to
position all the pistons at their mid-stroke.
23 Select the correct thickness of head
gasket required by determining the largest
amount of piston protrusion, and using the
following table.
Piston protrusion Gasket thickness
measurement (mm) required
0.020 to 0.100 0.77 to 0.87 (no holes)
0.101 to 0.200 0.87 to 0.97 (one hole)
0.201 to 0.295 0.97 to 1.07 (two holes)
Refitting
24 Wipe clean the mating surfaces of the
cylinder head and cylinder block/crankcase.
Place the new gasket in position with the words
ALTO/TOP uppermost (see illustration).
25 Carefully refit the cylinder head assembly to
the block, aligning it with the locating dowels.
26 Apply a thin film of engine oil to the bolt
threads and the underside of the bolt heads.
Carefully enter each new cylinder head bolt into
its relevant hole (do not drop them in). Screw all
bolts in, by hand only, until finger-tight.
27 Working progressively in sequence,
tighten the cylinder head bolts to their Stage 1
torque setting, using a torque wrench and
suitable socket (see illustration). Working
again in the same sequence, go around and
tighten all bolts through the specified Stage 2
torque setting.
28 Once all bolts have been tightened to the
Stage 2 torque, working again in the same
sequence, go around and tighten all bolts
through the specified Stage 3 angle, then
through the specified Stage 4 angle, and
finally through the specified Stage 5 angle
using an angle-measuring gauge.
12.24 Place the new gasket in position with the words ALTO/TOP
uppermost
12.27 Cylinder head bolt tightening sequence