Opel Frontera UBS. Manual - part 443

6A – 62 ENGINE MECHANICAL

3. Spring tension

1) Use a spring tester to compress the springs to

the installed height. Measure the compressed
spring tension.

2) Replace the springs if the measured tension is

below the specified limit.

Standard: 236.0 N (24 kg/53 lb)
Limit: 205.0 N (21 kg/46 lb)

Valve Guide

CAUTION: Taking care not to damage the valve seat
contact surface, when removing carbon adhering to
the valve head.
Carefully inspect the valve stem for scratching or
abnormal wear. If these conditions are present, the
valve and the valve guide must be replaced as a set.

1. Valve Guide Clearance

1) Measure the valve stem diameter with a

micrometer.
If the valve stem diameter is less than the
specified limit, the valve and the valve guide
must be replaced as a set.

Diameter of Valve stem:Inlet

Standard: 6.959 – 6.977 mm (0.2740 – 0.2747 in)
Limit: 6.92 mm (0.2724 in)

Diameter of Valve stem:Exhaust

Standard: 6.952 – 6.97 mm (0.2737 – 0.2744 in)
Limit: 6.90 mm (0.2717 in)

2) Measure the inside diameter of the valve guide

with a micrometer.

3) Subtract the measured outer diameter of the

valve stem from the measured inner diameter of
the valve guide.
If the valve exceeds the specified limit, the valve
and the valve guide must be replaced as a set.

Inlet clearance

Standard: 0.023 – 0.053 mm (0.0009 – 0.0021 in)
Limit: 0.19 mm (0.0075 in)

Exhaust clearance

Standard: 0.03 – 0.063 mm (0.0012 – 0.0025 in)
Limit: 0.20 mm (0.0079 in)

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ENGINE MECHANICAL 6A – 63

Valve Guide Replacement

1. Using the special tool, drive out the valve guide

from the combustion chamber side.
Valve guide replacer: 9-8523-1212-0

2. Apply engine oil to the outside of the valve guide.

Using the special tool, drive in a new valve guide
from cylinder head upper face side, and check the
valve guide height.
Valve guide replacer: 9-8523-1212-0

Height: 8.0 mm (0.315 in)

NOTE: If the valve guide has been removed, both the
valve and the valve guide must be replaced as a set.

Valve Thickness

1. Measure the valve thickness.
2. If the measured value is less than the specified

limit, the valve and the valve guide must be
replaced as a set.

Inlet

Standard: 1.2 mm (0.0472 in)
Limit: 1.1 mm (0.0433 in)

Exhaust

Standard: 1.2 mm (0.0472 in)
Limit: 1.1 mm (0.0433 in)

Contact surface angle on valve seat on
valve

1. Measure contact surface angle on valve seat.

2. If the measured value exceeds the limit, replace

valve, valve guide and valve seat as a set.

Standard: 68°

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6A – 64 ENGINE MECHANICAL

Valve Depression

1. Measure the valve stem height from the upper

surface of the cylinder head as shown in the
illustration.

Standard: 
Intake side

35.59 mm (1.4012 in)

Exhaust side 35.49 mm (1.3972 in)

Limit:
Intake side

35.74 mm (1.4071 in)

Exhaust side 35.64 mm (1.4031 in)

Legend

(1) Intake Side
(2) Exhaust Side

Valve Contact Width

1. Check the valve contact faces for roughness and

unevenness. Make the valve contact surfaces
smooth.

2. Measure the valve contact width.

If the measured value exceeds the specified limit,
the valve seat insert must be replaced.

Inlet
Standard: 2.1 mm (0.0827 in)
Limit: 2.6 mm (0.1024 in)

Exhaust
Standard: 2.0 mm (0.0787 in)
Limit: 2.5 mm (0.0984 in)

Valve Seat Insert Replacement

Valve Seat Insert Removal

1. Arc weld the entire inside circumference of the

valve seat insert.

2. Allow the valve seat insert to cool for a few minutes.

This will invite contraction and make removal of the
valve seat insert easier.

3. Use a screwdriver to pry the valve seat insert free.

Take care not to damage the cylinder head.

4. Carefully remove carbon and other foreign material

from the cylinder head insert bore.

1

2

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ENGINE MECHANICAL 6A – 65

Valve Seat Insert Installation

1. Carefully place the attachment (1) (having a smaller

outside diameter than the valve seat insert) on the
valve seat insert (2).

Legend

(1) Attachment
(2) Valve Seat Insert
(3) Bench Press

NOTE: The smooth side of the attachment must contact
the valve seat insert.

2. Use a bench press (3) to gradually apply pressure

to the attachment and press the valve seat insert
into place.

Note: Do not apply an excessive amount of pressure
with the bench press. Damage to the valve seat insert
will result.

Valve Seat Insert Correction

1. Remove the carbon from the valve seat insert

surface.

2. Use a valve cutter (15°, 45° and 75° blades) to

minimize scratches and other rough areas. This will
bring the contact width back to the standard value.
Remove only the scratches and rough areas. Do
not cut away too much. Take care not to cut away
unblemished areas of the valve seat surface.

Valve Seat Angle: 45°

NOTE: Use an adjustable valve cutter pilot.
Do not allow the valve cutter pilot to wobble inside the
valve guide.

3. Apply abrasive compound to the valve seat insert

surface.

4. Insert the valve into the valve guide.
5. Turn the valve while tapping it to fit the valve seat

insert.

6. Check that the valve contract width is correct.
7. Check that the valve seat insert surface is in

contact with the entire circumference of the valve.

3

2

1

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150

°

90

°

30

°

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