ISUZU 4JJ1 Engine Valve Stem Seal and Spring Removal & Installation

This instruction show you guide on how to remove and install valve stem seal and valve spring for ISUZU Euro 4 N 4JJ1 engine truck.More about ISUZU truck cases,please refer to::ISUZU Trouble Repair.



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1.Remove the cylinder head from the engine.

2.Remove the valve stem end cap.

3.Remove the split collar.

Special Tool

Valve spring compressor adaptor:


Valve spring replacer:



4.Remove the spring upper seat.

Use a special tool to remove the upper seat.

5.Remove the valve springs.

Organize the removed valve springs in the order of the cylinder number.

6Remove the inlet and exhaust valves.

Organize the removed valves by the cylinders using tags, etc.


7Remove the valve stem oil seal.

Remove the oil seal using pliers.


NOTE: Do not reuse the removed oil seal.

8.Remove the spring lower seat.


Inspection Inspect the valve springs


Visually inspect the valve spring for damage or excess wear. Replace if necessary.

1.Free length

Measure the spring free length. If it is lower than the specified limit, replace the spring.




2.Degree of perpendicular condition

Measure the degree of perpendicular condition with a right-angle gauge.Replace the valve spring if the measured value exceeds the limit.



Using a spring tester, compress the spring to the installation height. Measure the compressed spring tension. If the measured tension is lower than the limit, replace the spring.




1.Install the spring lower seat.

2.Install the valve stem oil seal.

Apply engine oil to outer circumference of the valve guide and install the oil seal using the valve stem seal setting tool.

Special Tool Valve stem seal installer:


NOTE: After installing the valve stem oil seal, check that it issecurely inserted all the way in, and that the oil seal isnot inclined or that the garter spring will not come off.



3.Install the inlet and exhaust valves.

Apply engine oil to the valve stem and install the valve.



4.Install the valve spring

NOTE: Yellow paint is applied on the exhaust side, so be careful for incorrect assembly.

5.Install the spring upper seat.

6.Mount the split collar.

Using a replacer, compress the valve spring to install the split collar.

Special Tool

Valve spring compressor adaptor:


Valve spring replacer:




NOTE: Move it up and down to confirm that it moves smoothly.

7.Install the valve stem end cap.

8.Install the cylinder head to the engine.

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