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Figure 15 Cylinder head nuts
tightening sequence
10.
Clean the face of the cylinder head and remove all trace of
carbon and high spots.
11.
Clean out the waterways. If deposits exist on the piston
crowns proceed as follows:-
(a)
Turn the crankshaft until pistons 1 and 4 are at the top.
(b)
Fill the cylinders of pistons 2 and 3 with clean non fluffy rag
to stop carbon falling in to the bores. Cover the cam follower
apertures.
(c)
Carefully, without scoring the crowns, clean the carbon
deposits leaving a narrow band approximately 3.1 mm (1/8 in) around
the perimeter to maintain the gas seal. Avoid carbon deposits
entering the waterways.
(d)
Turn the crankshaft until pistons 2 and 3 are uppermost and
repeat.
Re-assembly and replacement
1.
Clean the cylinder block face removing all traces of carbon
and any high spots.
2.
Replace the valve guides in the cylinder head using special
tool R 7478 (Figure 15).
3.
Lap in the valves using fine grinding paste until a gas tight
seal is attained. Ensure valves are refitted in their original positions
and that all trace of grinding paste is removed.
4.
Lubricate the valve stems with engine oil and assemble the
cylinder head. Ensure that the valve spring collars and collets are
correctly seated. Renew the valve stem seals.
Refit the cylinder head using a new gasket.
Operation 11
Pistons, connecting rods and bearing
replacement (head and sump removed)
To remove
1.
Remove oil pump assembly (Operation 4).
2.
Turn the crankshaft to bring numbers 1 and 4 connecting
rod bolts to an accessible position.
3.
Check the identifying marks on the bearing caps and
connecting rods. Mark if necessary.
Figure 16 Valve guide removal and replacement
1.
Valve guide removal
2.
Valve guide replacement
3.
Valve guide protection sleeve
4.
Release the tab washers, unscrew the bolts and remove the
big end bearing caps complete with shells
5.
Push the piston/con rod assemblies out through the top
and carefully withdraw, keeping the end caps with their respective
con rods.
Overhaul
1.
Immerse the pistons and con rod assemblies in hot water
for a few minutes. remove the circlips retaining the gudgeon pins.
2.
Using a suitable drift, remove the gudgeon pins and
disconnect the con rods from the pistons.
3.
Check the small end bushes for wear and, if necessary,
remove the old bushes using a hand press and fit new ones. Ensure
that the oil hole in the new bush is correctly aligned with the oil hole
in the con rod.
4.
Having fitted the new bushes, check that the gudgeon pins
will fit. It might be necessary to ream out the bushes (using an
expanding reamer) to achieve a tight sliding fit.
Note: It is vital during this operation that the bush is reamed squarely
to the con rod to ensure correct alignment.
5.
Remove the piston rings and clean.
6.
Clean the pistons, removing all carbon deposits, particularly
from the ring grooves.
7.
Assemble the pistons to the connecting rods using new
circlips. It might be necessary to heat the pistons in hot water to
enable the gudgeon pins to be pushed through.
Note: Engines up to number 5K/85/100226 have angle con rods which
must be assembled with the cutaway to the camshaft side.
8.
Before fitting the piston rings to the pistons, place each ring
in its appropriate liner to measure the ring gap. This should be
between 0.17 to 0.30 mm (0.007 to 0.012 in).
9.
Fit the piston rings to the pistons, starting with the oil
scraper ring, followed by the taper compression ring, then the
compression ring.
Page 32
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