Isuzu 4HK1 — Cylinder head assembly disassembly

Repair & overhaul

For the Isuzu 4HK1, from the Isuzu service manual.

Applies to: Isuzu 4HK1

Procedure

1. Remove the front and rear engine hanger brackets from the cylinder head assembly.
2. Remove the inlet cover from the cylinder head assembly together with the EGR pipe D.
3. Remove the exhaust manifold bracket and the exhaust manifold from the cylinder head assembly.
4. Remove the water outlet pipe, then the thermostat and the gasket from the thermostat.
5. Remove the overheat switch from the cylinder head assembly.
6. Remove the engine coolant temperature sensor from the cylinder head assembly.
7. Remove the CMP sensor from the cylinder head assembly without subjecting the sensor to shock.
8. Tap and tilt the idle gear C cover, remove it with pliers, then remove idle gear C.
9. Press the valve spring with the special tool, remove the split collar, then the valve spring seat and valve spring.
10. Remove the inlet valve and exhaust valve, organizing them according to the cylinders.
11. Remove the valve stem oil seal with pliers (do not reuse) and the valve spring seat.
12. Remove the valve guide using the special tool, tapping out from the bottom surface of the cylinder head.
13. Heat the valve seat insert with the gas burner, cool naturally, then remove it using the driver.
14. Remove the injector sleeve using the special tool, tapping out from the bottom surface of the cylinder head.
15. Weld a nut to the bridge guide, remove it with the sliding hammer, then remove the oil seal.

Full service-parts list: Isuzu 4HK1 →

Source: Isuzu service manual. Steps and values are as documented; always cross-check against the official manual and any later revisions for your exact serial number before servicing.

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