Daewoo Nubira. Manual — part 153
1C – 70
I
DOHC ENGINE MECHANICAL
DAEWOO V–121 BL4
28. Compress the valve springs with the valve spring
compressor KM–348 and the adapter KM–653.
29. Remove the valve retainers.
30. Remove the valve spring compressor KM–348 and
the adapter KM–653.
31. Remove the valve spring caps.
32. Remove the valve springs. Maintain the original
position of the valve springs for installation.
33. Remove the valves. Maintain the original position of
the valves for installation.
34. Remove the valve stem seals.
Cylinder Head Inspection
1. Clean the sealing surfaces.
2. Inspect the cylinder head gasket and mating sur-
faces for leaks, corrosion and blow–by.
3. Inspect the cylinder head for cracks.
4. Inspect the length and width of the cylinder head
using a feeler gauge and a straight edge.
5. Check the sealing surfaces for deformation and
warpage. The cylinder head sealing surfaces must
be flat within 0.025 mm (0.001 inch) maximum.
DOHC ENGINE MECHANICAL 1C – 71
DAEWOO V–121 BL4
6. Measure the height of the cylinder head from seal-
ing surface to sealing surface. The cylinder head
height should be 133.975 to 134.025 mm (5.274 to
5.276 inches). If the cylinder head height is less
than 133.9 mm (5.271 inches), replace the cylinder
head.
7. Inspect all threaded holes for damage.
8. Inspect valve seats for excessive wear and burned
spots.
Valve Inspection
1. Inspect the valve stem tip for wear.
2. Inspect the valve retainer grooves and the oil seal
grooves for chips and wear.
3. Inspect the valves for burns or cracks.
4. Inspect the valve stem for burrs and scratches.
5. Inspect the valve stem. The valve stem must be
straight.
6. Inspect the valve face for grooving. If the groove is
so deep that refacing the valve would result in a
sharp edge, replace the valve.
7. Inspect the valve spring. If the valve spring ends
are not parallel, replace the valve spring.
8. Inspect the valve spring seating surface of the
valve rotators for wear or gouges. Replace as re-
quired.
Cleaning Procedure
1. Clean the cylinder head.
2. Clean the valve guides.
3. Clean all of the threaded holes.
4. Clean the valves of carbon, oil, and varnish.
1C – 72
I
DOHC ENGINE MECHANICAL
DAEWOO V–121 BL4
Cylinder Head Overhaul
Valve Grind–in
1. Lubricate the valve seat using a fine–grained paste.
2. Lift the valve rhythmically from the seat with a com-
mercially–available valve grinding tool in order to
distribute the paste.
3. Check the contact pattern on the valve head and in
the cylinder head.
4. Clean the valves, the valve guides, and the cylinder
head.
Valve Grind
1. Ensure that there are no crater line burns on the
valve cone.
2. The valve may be reground only two times. Do not
grind the valve stem end.
3. Ensure that the angle at the valve face is 45 de-
grees.
4. Inspect the assembly height of the intake valves
and the exhaust valves.
DOHC ENGINE MECHANICAL 1C – 73
DAEWOO V–121 BL4
Valve Guide – Ream
1. Measure the diameter of the valve guide using
gauge MKM–571–B and a commercially–available
inside micrometer.
Important : Valve oversizes may already have been fitted
in production.
2. An oversize service code is on the valve guide and
the valve stem end. The following table gives the
correct size, reamer, and production code for each
service.
Size
Reamer
Productio
n Code
Service
Code
Normal
–
–
K
0.075
KM–805
1
K1
0.150
2
K2
3. Ream the valve guide from the upper side of the
cylinder head to the next oversize.
4. After reaming, cross out the code and emboss the
valve guide with the new code.
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