engine ISUZU KB P190 2007 Workshop Repair Manual

Engine Mechanical – V6 Page 6A1–166

10 Remove the cylinder head oil gallery expansion
plugs (1).

Figure 6A1 – 285
11 Remove the cylinder head coolant threaded plugs (1).

Figure 6A1 – 286
Clean
CAUTION
Due to the aluminium alloy construction of
the cylinder head, wire brushes and steel
scrapers must not be used during the
cleaning process, as damage to sealing
surfaces may occur. Use a wood or plastic
scraper as an alternative.
1 Remove any old thread sealant, gasket material or sealant using commercially available plastic or wooden scraper.
2 Clean all cylinder head surfaces with non-corrosive solvent.

Safety glasses must be worn when using
compressed air.
3 Blow out all the oil galleries using compressed air.
4 Remove any carbon deposits from the combustion chambers.
5 Clean any debris or build-up from the lifter pockets.

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ISUZU KB P190 2007

Engine Mechanical – V6 Page 6A1–167

Inspect
Visual Inspection
1 Inspect the cylinder head (1) camshaft bearing
surfaces for the following conditions:
• excessive scoring or pitting,
• discoloration from overheating, and
• deformation from excessive wear.
2 If any of the above conditions exist on the camshaft bearing surfaces, replace the cylinder head. Do not
machine the camshaft bearing journals.

Figure 6A1 – 287
3 Inspect the cylinder head for the following: • Cracks, damage or pitting in the combustion chambers.
• Debris in the oil galleries. continue to clean the galleries until all debris is removed.
• Coolant leaks or damage to the deck face sealing surface. if coolant leaks are present, measure the surface
warpage as described under Cylinder Head Measurement within this Section.
• Burrs or any defects that would degrade the sealing of a new secondary camshaft chain tensioner gasket.
• Damage to any gasket surfaces.
• Damage to any threaded bolt holes.
• Burnt or eroded areas in the combustion chamber.
• Cracks in the exhaust ports and combustion chambers.
• External cracks in the water passages.
• Restrictions in the intake or exhaust passages.
• Restrictions in the cooling system passages.
• Rusted, damaged or leaking core plugs.
4 If the cylinder head is cracked or damaged, it must be replaced. No welding or patching of the cylinder head is recommended.
Cylinder Head Measurement
NOTE
For all cylinder head and associated component
specifications, refer to 5 Specifications.
Camshaft Journal Clearance
1 Install the camshaft bearing cap in the cylinder head without the camshaft.
2 Install the camshaft cap bolts and tighten to the correct torque specification
Camshaft bearing cap attaching bolt........8.0 – 12.0 Nm.
3 Measure the camshaft bearings using an inside micrometer.
4 Subtract the camshaft journal diameter from the camshaft bearing diameter. This will provide the running clearance. If the running clearance exceeds specifications and the camshaft journals are within specification, replace the
cylinder head.
Camshaft Journal Alignment
1 Ensure the camshafts are serviceable, refer to 3.19 Camshaft for measuring procedures.

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ISUZU KB P190 2007

Engine Mechanical – V6 Page 6A1–168

2 Inspect the cylinder head camshaft bearing surfaces for any imperfections or scratches that could inhibit correct
camshaft clearances. Repair minor imperfections or scratches.
3 Install the camshafts in the cylinder head.
4 Install the camshaft bearing caps.
5 Install the camshaft cap bolts and tighten to the correct torque specification.
Camshaft bearing cap attaching bolt........8.0 – 12.0 Nm.
6 Ensure the camshafts spin freely in the cylinder head. If the camshaft does not run freely, replace the cylinder head.
Deck Flatness Inspection
1 Ensure the cylinder head decks are clean and free of gasket material.
2 Inspect the surface for any imperfections or scratches that could inhibit correct cylinder head gasket sealing.
3 Place a straight-edge (1) diagonally across the cylinder head (2) deck face surface.
4 Measure the clearance between the straight-edge and the cylinder head deck face using a feeler gauge
at four points along the straight-edge.
5 If the warpage is less than 0.05 mm, the cylinder head deck surface does not require resurfacing.
6 If the warpage is between 0.05±0.20 mm or any imperfections or scratches that could inhibit correct
cylinder head gasket sealing are present, the cylinder
head deck surface requires resurfacing.
7 If resurfacing is required the maximum amount that can be removed is 0.25 mm.
8 If the cylinder head deck surface requires more than 0.25 mm material removal the head must be
replaced.
Figure 6A1 – 288

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ISUZU KB P190 2007

Engine Mechanical – V6 Page 6A1–169

Valve Guide Measurement
1 Measure the valve stem (1) to-guide (2) clearance.
Excessive valve stem-to-guide clearance may cause
excessive oil consumption and may also cause a
valve to break. Insufficient clearance will result in
noisy and sticky functioning of the valve and will
disturb the engine assembly smoothness.
2 Clamp a dial indicator to the cylinder head at the camshaft cover rail.
3 Locate the dial indicator so the movement of the valve stem from side to side, crossways to the cylinder
head, will cause a direct movement of the indicator
stem. The dial indicator stem must contact the side of
the valve stem just above the valve guide.
4 Drop the valve head about 0.064 mm off the valve seat.
5 Use light pressure when moving the valve stem from side to side to obtain a clearance reading, refer to 5
Specifications.
• If the clearance for the valve is greater than
specified and a new standard diameter valve
stem will not bring the clearance within
specifications, the valve guide may be oversized
by 0.075 mm using the valve guide reamer, Tool
No. J 42096 or by 0.375 mm using the valve
guide reamer, Tool No. EN-46120. Two sizes of
oversized valve stems are available for service.
• Valve guide wear at the bottom 10 mm of the
valve guide is not significant enough to affect
normal operation.
• If over sizing the guide does not bring the
clearance within specifications, replace the
cylinder head.
Figure 6A1 – 289
Valve Spring Inspection and Measurement
Inspection Procedure
1 Clean the valve springs in solvent.

Safety glasses must be worn when using
compressed air
2 Dry the valve springs with compressed air.
3 Inspect the valve springs for broken coils or coil ends.

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ISUZU KB P190 2007

Engine Mechanical – V6 Page 6A1–170

Measurement Procedure
1 Use a commercially available valve spring tester to
measure the valve spring tension, refer to 5
Specifications.
CAUTION
Do not use shims to increase spring load.
The use of shims can cause the valve spring
to bottom out before the camshaft lobe is at
peak lift.
2 If low valve spring load is found, replace the valve springs.



Figure 6A1 – 290
Valve and Seat Grinding
Valve Cleaning Procedure
CAUTION
Do not use a wire brush on any part of the
valve stem. The valve stem is chrome plated
to provide enhanced wear characteristics.
Wire brushing the stem could remove the
chrome plating.
1 Use soft bristle brush to clean any carbon build-up from the valve head.
2 Thoroughly clean the valve with solvent and wipe dry.
Valve Visual Inspection Procedure
1 Inspect the valve for damage from the head to tip for the following conditions:
• pitting in the valve seat area (1),
• lack of valve margin (2),
• bending in the valve stem (3),
• pitting or excessive wear in the stem (4),
• worn valve key grooves (5), and
• worn valve tip (6).
2 Replace the valve if any of these conditions exist.

Figure 6A1 – 291
Valve Measurement and Reconditioning Overview
Correct valve service is critical to engine performance. Therefore, all detailed measurement procedures must be followed
to identify components that are out of specification. If the measurement procedures reveal the valve or valve seat must
be reconditioned, it is critical to perform the measurement procedures after reconditioning.

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ISUZU KB P190 2007

Engine Mechanical – V6 Page 6A1–171

Valve Seat Width Measurement Procedure
1 Measure the valve seat (1) width in the cylinder head
using a scale (2).

Figure 6A1 – 292
2 Measure the seat width on the valve face (1) using a correct scale.
CAUTION
The seat contact area must be at least
0.5 mm from the outer diameter (margin) of
the valve. If the contact area is too close to
the margins, the seat must be reconditioned
to move the contact area away from the
margin.
3 Compare the measurements with the specifications, refer to 5 Specifications.
4 If the seat widths are acceptable, check the valve seat roundness, refer to Valve Seat Roundness
Measurement Procedure in this Section.
5 If the seat width is not acceptable, grind the valve seat to bring the width back to specification. Correct
valve seat width is critical to providing the correct
amount of valve heat dissipation, refer to Valve and
Seat Reconditioning Procedure in this Section.

Figure 6A1 – 293
Valve Seat Roundness Measurement Procedure
1 Measure the valve seat roundness using a dial indicator attached to a tapered pilot installed in the guide. The pilot should have a slight bind when installed in the guide.
CAUTION
The correct size pilot must be used. Do not
use adjustable diameter pilots. Adjustable
pilots may damage the valve guides.
2 Compare your measurements with the specifications, refer to 5 Specifications.
3 If the valve seat exceeds the roundness specification, grind the valve and valve seat, refer to Valve and Seat Reconditioning Procedure in this Section.
4 If new valves are being used, the valve seat roundness must be within 0.05 mm.

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ISUZU KB P190 2007

Engine Mechanical – V6 Page 6A1–172

Valve Margin Measurement Procedure
1 Measure the valve margin using an appropriate scale.
2 Refer to 5 Specifications for minimum valve margin and compare them to your measurements.
3 If the valve margins are beyond specification, replace the valves.
4 If the valve margins are within specification and do not require refacing, test the valve for seat
concentricity, refer to Valve-to-Seat Concentricity
Measurement Procedure in this Section.

Figure 6A1 – 294
Valve-to-Seat Concentricity Measurement Procedure
Checking the valve-to-seat concentricity determines whether the valve and seat are sealing correctly.
Measure the valve face and the valve seat to ensure correct valve sealing.
1 Coat the valve face lightly with blue dye (3).
2 Install the valve in the cylinder head.
3 Turn the valve against the seat with enough pressure to wear off the dye.
4 Remove the valve from the cylinder head.
5 Inspect the valve face.
NOTE
• If the valve face is concentric, providing a
correct seal, with the valve stem, a continuous
mark (1) will be made around the entire face (2).
• The wear mark must be at least 0.5 mm from
the margin of the valve. If the wear mark is too
close to the margin, the seat must be
reconditioned to move the contact area away
from the margin.
• If the face is not concentric with the stem, the
mark will not be continuous around the valve
face. The valve should be refaced or replaced
and the seat must be reconditioned, refer to
Valve and Seat Reconditioning Procedure in
this Section.
Figure 6A1 – 295
Valve and Seat Reconditioning Procedure
If the valve seat width, roundness or concentricity are beyond specifications, grind the seats in order to ensure correct
heat dissipation and prevent the build up of carbon on the seats.
If valve seat reconditioning is required, reface the valve face, unless a new valve is used.

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ISUZU KB P190 2007

Engine Mechanical – V6 Page 6A1–173

1 Grind the valve seats (2) to the correct angle
specification, refer to 5 Specifications.
2 Using the correct angle specification, grind and relieve the valve seats (1) to correctly position the
valve seating surface (2) to the valve.
3 Using the correct angle specification, grind and undercut the valve seats (3) to narrow the valve seat
widths to the specifications, refer to 5 Specifications.
4 If the original valve is being used, grind the valve to the specifications, refer to 5 Specifications.
Measure the valve margin again after grinding, refer
to Valve Margin Measurement Procedure in this
Section. Replace the valve if the margin is out of
specification. New valves do not require grinding.
5 W hen grinding the valves and seats, grind off as little material as possible. Cutting valve seat results in
lowering the valve spring pressure.
6 Install the valve in the cylinder head.
Figure 6A1 – 296
CAUTION
If using refaced valves, lap the valves into the
seats with a fine grinding compound. The
refacing and reseating operations should
leave the refinished surfaces smooth and true
so that minimal lapping is required. Excessive
lapping will groove the valve face and prevent
a good seat when hot.
NOTE
• Clean any remaining lapping compound from
the valve and seat with solvent and
compressed air prior to final assembly.
• If fitting new valves, do not lap the valves
under any condition.

7 After obtaining the correct valve seat width in the cylinder head, measure the valve stem height, refer to Valve Stem Height Measurement Procedure in this Section.
8 If the valve stem height is acceptable, test the seats for concentricity, refer to Valve-to-Seat Concentricity Measurement Procedure in this Section.

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ISUZU KB P190 2007

Engine Mechanical – V6 Page 6A1–174

Valve Stem Height Measurement Procedure
CAUTION
To determine the valve stem height
measurement, measure from the valve
spring seat to the valve spring retainer.
1 Install the valve into the valve guide.
2 Ensure the valve is seated to the valve seat.
3 Install the valve stem oil seal.
4 Install the valve spring retainer and valve stem keys.
5 Measure the distance (1) between the cylinder head to the bottom of the valve spring retainer, refer to 5
Specifications.
6 If the maximum height specification is exceeded, a new valve should be installed and the valve stem
height re-measured.
Figure 6A1 – 297
CAUTION
Do not grind the valve stem tip. The tip of the
valve is hardened and grinding the tip will
eliminate the hardened surface causing
premature wear and possible engine damage.
CAUTION
Do not use shims to adjust valve stem height.
The use of shims will cause the valve spring
to bottom out before the camshaft lobe is at
peak lift and engine damage could result.
7 If the valve stem height still exceeds the maximum height specification, the cylinder head must be replaced.
Assemble
1 Install the cylinder head coolant threaded plugs (1) and tighten to the correct torque specification.




Cylinder head threaded plug ..............................31.0 Nm

Figure 6A1 – 298

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ISUZU KB P190 2007

Engine Mechanical – V6 Page 6A1–175

2 Install the cylinder head oil gallery expansion
plugs (1).
Figure 6A1 – 299
CAUTION
• Never reuse a valve stem oil seal. Always
use new seals when assembling the
cylinder head.
• Force should only be applied to the valve
spring contact area of the new valve stem
oil seal during installation.
3 Fit the valve stem oil seals onto the guides using Tool No. EN-46116 (1).
4 Push and twist the valve stem oil seal into position on the valve guide until the seal positively locks on the
guide using Tool No. EN-46116.
5 Lubricate the valve stem and valve guide ID with clean engine oil.

Figure 6A1 – 300
CAUTION
The valve stem oil seal must not come loose
from the valve guide when the valve (1) is
installed.
6 Insert the valve into the valve guide until it bottoms on the valve seat.


Figure 6A1 – 301

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