Cylinder Head And Valves; Using Valve Spring Compressor, Compress Valve Spring; Extract Two Split Collets By Hooking Them Out Using Small Screwdriver; Remove The Valve Spring Cap - Opel Zafira B MPV 2006 Owners Workshop Manual

4 Extract the two split collets by hooking them
out using a small screwdriver, then slowly
release the compressor tool
(see illustration).
5 Remove the valve spring cap and the
spring, then withdraw the valve through the
combustion chamber. Using pliers, remove the
valve stem oil seal, which also incorporates
the spring seat on most engines (see
illustrations).
If the spring seat is not part of
the valve stem oil seal, hook it out using a
small screwdriver.
6 Repeat the procedure for the remaining
valves, keeping all components in strict order
so that they can be refitted in their original
positions, unless all the components are to
be renewed. If the components are to be kept
and used again, place each valve assembly
in a labelled polythene bag or a similar small
container
(see illustration).
Note that as with
cylinder numbering, the valves are normally
numbered from the timing chain (or timing
belt) end of the engine. Make sure that the
valve components are identified as intake and
exhaust, as well as numbered.
1
Thorough cleaning of the cylinder head and
valve components, followed by a detailed
inspection, will enable you to decide how
much valve service work must be carried
out during the engine overhaul.
Note: If the
engine has been severely overheated, it is best
to assume that the cylinder head is warped -
check carefully for signs of this.
Cleaning
2 Scrape away all traces of old gasket
material from the cylinder head.
3 Scrape away the carbon from the
combustion chambers and ports, then wash
the cylinder head thoroughly with paraffin or a
suitable solvent.
4 Scrape off any heavy carbon deposits
that may have formed on the valves, then
use a power-operated wire brush to remove
deposits from the valve heads and stems.
Inspection
Note:
Be sure to perform all the following
6.5c ... then withdraw the valve through
the combustion chamber
Engine removal and overhaul procedures 2E•9
6.2 Using a valve spring compressor,
compress the valve spring to relieve the
pressure on the collets
inspection procedures before concluding
that the services of a machine shop or engine
overhaul specialist are required. Make
a
list of
all items that require attention.
Cylinder head
5 Inspect the head very carefully for cracks,
evidence of coolant leakage, and other
damage. If cracks are found, a new cylinder
head should be obtained.
6 Use a straight-edge and feeler gauge blade
to check that the cylinder head surface is
not distorted (see illustration). If it is, it may
be possible to resurface it, provided that the
cylinder head is not reduced to less than the
minimum specified height
7 Examine the valve seats in each of the
combustion chambers. If they are severely
pitted, cracked or burned, then they will need
to be recut by an engine overhaul specialist.
If they are only slightly pitted, this can be
6.5a Remove the valve spring cap ...
6.5d Using pliers, remove the valve stem
oil seal, which also incorporates the spring
seat on most engines
6.4 Extract the two split collets by hooking
them out using a small screwdriver
removed by grinding-in the valve heads and
seats with fine valve-grinding compound, as
described below.
8 If the valve guides are worn, indicated by
a side-to-side motion of the valve, oversize
valve guides are available, and valves with
oversize stems can be fitted. This work is best
carried out by an engine overhaul specialist. A
dial gauge may be used to determine whether
the amount of side play of a valve exceeds the
specified maximum.
9 Check the tappet bores in the cylinder head
for wear. If excessive wear is evident, the
cylinder head must be renewed. Also check
the tappet oil holes in the cylinder head for
obstructions.
Valves
10 Examine the head of each valve for pitting,
burning, cracks and general wear, and check
the valve stem for scoring and wear ridges.
6.5b ... and the spring ...
6.6 Place each valve assembly in a
labelled polythene bag or similar container