Daewoo Nubira. Manual - part 153

1C – 70

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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.

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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.

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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.

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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.