Suzuki Grand Vitara JB416 / JB420 / JB419. Manual - part 145

1D-106 Engine Mechanical: For J20 Engine

Valve
Visual inspection
• Remove all carbon from valves.
• Inspect each valve for wear, burn or distortion at its 

face and stem end, as necessary, replace it.

• Inspect valve stem end face for pitting and wear. If 

pitting or wear is found there, valve stem end may be 
resurfaced, but not too much to grind off its chamber. 
When it is worn out too much that its chamber is gone, 
replace valve.

Valve head thickness
Measure thickness “a” of valve head. If measured 
thickness exceeds limit, replace valve.

Valve head thickness “a”
Intake
Standard: 1.25 – 1.55 mm (0.049 – 0.061 in.)
Limit: 0.9 mm (0.035 in.)
Exhaust
Standard: 1.45 – 1.75 mm (0.057 – 0.069 in.)
Limit: 1.1 mm (0.04 in.)

Valve head radial runout
Check each valve for radial runout with a dial gauge and 
“V” block. To check runout, rotate valve slowly. If runout 
exceeds its limit, replace valve.

Valve head radial runout
Limit: 0.08 mm (0.003 in.)

Seating contact width
Create contact pattern on each valve in the usual 
manner, i.e., by giving uniform coat of marking 
compound to valve seat and by rotatingly tapping seat 
with valve head. Valve lapper (tool used in valve lapping) 
must be used. 
Pattern produced on seating face of valve must be a 
continuous ring without any break, and the width of 
pattern must be within specified range.

Standard seating width “a” revealed by contact 
pattern on valve face
Intake and Exhaust: 1.0 – 1.4 mm (0.0389 – 0.0551 
in.)

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Engine Mechanical: For J20 Engine 1D-107

Valve seat repair
A valve seat not producing a uniform contact with its 
valve or showing width of seating contact that is out of 
specified range must be repaired by regrinding or by 
cutting and regrinding and finished by lapping.

1) Exhaust valve seat:

Use valve seat cutters (1) to make two cuts as 
illustrated in the figure. Two cutters must be used: 
the first for making 15

° angle, and the second for 

making 45

° angle. The second cut must be made to 

produce desired seat width.

Seat width for exhaust valve seat
“a”: 1.0 – 1.4 mm (0.0389 – 0.0551 in.)

2) Intake valve seat: 

Use valve seat cutters (1) to make three cuts as 
illustrated in the figure. Three cutters must be used: 
the 1st for making 25

° angle, the 2nd for making 60° 

angle, and 3rd for making 45

° angle. The 3rd cut 

(45

°) must be made to produce desired seat width.

Seat width for intake valve seat
“b”: 1.0 – 1.4 mm (0.0389 – 0.0551 in.)

3) Valve lapping:

Lap valve on seat in two steps, first with coarse size 
lapping compound applied to face and the second 
with fine-size compound, each time using valve 
lapper according to usual lapping method.

Cylinder Head Inspection

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• Remove all carbon deposits from combustion 

chambers.

NOTE
Do not use any sharp-edged tool to scrape 
off carbon deposits. Be careful not to scuff or 
nick metal surfaces when decarbonizing. The 
same applies to valves and valve seats, too.

 

• Check cylinder head for cracks on intake and exhaust 

ports, combustion chambers, and head surface. Using 
a straightedge and thickness gauge, check flatness of 
gasketed surface at a total of 6 locations. If distortion 
limit is exceeded, correct gasketed surface with a 
surface plate and abrasive paper of about #400 
(Waterproof silicon carbide abrasive paper): place 
abrasive paper on and over surface plate, and rub 
gasketed surface against paper to grind off high spots. 
Should this fail to reduce thickness gauge readings to 
within limit, replace cylinder head. 
Leakage of combustion gases from this gasketed joint 
is often due to warped gasketed surface: such 
leakage results in reduced power output.

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1D-108 Engine Mechanical: For J20 Engine

Distortion for cylinder head surface on piston side
Limit: 0.03 mm (0.001 in.)

• Distortion of manifold seating faces: 

Check seating faces of cylinder head for manifolds, 
using a straightedge and thickness gauge, in order to 
determine whether these faces should be corrected or 
cylinder head replaced.

Distortion for cylinder head surface on intake and 
exhaust manifold
Limit: 0.05 mm (0.002 in.)

Valve Spring Inspection

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Valve Spring Free Length and Preload
Referring to data, check to be sure that each spring is in 
sound condition, free of any evidence of breakage or 
weakening. Remember, weakened valve springs can 
cause chatter, not to mention possibility of reducing 
power output due to gas leakage caused by decreased 
seating pressure.

Valve spring free length
Standard: 51.13 mm (2.013 in.)
Limit: 50.13 mm (1.974 in.)

Valve spring preload
Standard: 219 – 241 N (21.9 – 24.1 kg) for 37.60 mm 
(48.3 – 53.1 lb/1.480 in.)
Limit: 208 N (20.8 kg) for 37.60 mm (45.9 lb/1.480 in.)

Spring Squareness
Use a square and surface plate to check each spring for 
squareness in terms of clearance between end of valve 
spring and square. Valve springs found to exhibit a 
larger clearance than limit must be replaced.

Valve spring squareness
Limit: 1.6 mm (0.063 in.)

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Engine Mechanical: For J20 Engine 1D-109

Pistons, Piston Rings, Connecting Rods and Cylinders Components

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Pistons, Piston Rings, Connecting Rods and 
Cylinders Removal and Installation

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Removal

1) Remove engine assembly from vehicle referring to 

“Engine Assembly Removal and Installation: For J20 
Engine”.

2) Remove oil pump with oil pump strainer. Refer to “Oil 

Pump Removal and Installation: For J20 Engine in 
Section 1E” for removal.

3) Remove cylinder head. Refer to “Valves and 

Cylinder Head Removal and Installation: For J20 
Engine” for removal.

4) Mark cylinder number on all pistons, connecting rods 

and connecting rod caps.

5) Remove connecting rod bearing caps.
6) Clean carbon from top of cylinder bore before 

removing piston from cylinder.

7) Push piston and connecting rod assembly out 

through the top of cylinder bore.

Installation

1) Apply engine oil to pistons, rings, cylinder walls, 

connecting rod bearings and crank pins.

NOTE
Do not apply oil between connecting rod and 
bearing or between bearing cap and bearing.

 

2) When installing piston and connecting rod assembly 

into cylinder bore, point front mark (3) on piston head 
to crankshaft pulley side (1).

 1. Top ring

: “TOP” mark provided on piston ring comes to facing up.

8. Piston pin

 2. 2nd ring

: “TOP” mark provided on piston ring comes to facing up.

9. Piston pin circlip

3. Oil ring

10. Connecting rod bolt

: Check connecting rod bolt, plastic deformation tightening bolt, for deformation when 
reuse it due to plastic deformation tightening referring to “Connecting Rod Bolt” under 
“Pistons, Piston Rings, Connecting Rods and Cylinders Inspection and Cleaning: For 
J20 Engine” if it is reused.

4. Piston

: 15 N

⋅m (1.5 kgf-m, 11.0 lb-ft) 45° and 45° by the specified procedure.

 5. Connecting rod

: Apply engine oil to sliding surface of each part.

 6. Connecting rod bearing cap

: See “A”

: Do not reuse.

 7. Connecting rod bearing

: See “B”

“A”: Point arrow mark on cap to crankshaft pulley side. Do not apply engine oil to inner surface of bearing cap.
“B”: Do not apply engine oil between con-rod big end and bearing, between cap and bearing.

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2. Flywheel side

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