How to remove the timing gear of Isuzu engine (4JH1 type)
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1. Disconnect the battery cable negative terminal.
2. Drain the coolant.
3. Remove the radiator.Refer to “Radiator”in Section 6B Engine Cooling.
4. Remove the power steering pump and bracket assembly.
Refer to “Engine Assembly”in this Section.
5. Remove the AC generator drive belt.
Loosen AC Generator mounting bolt (under size) and adjust plate lock bolt, and remove the drive belt.
6. Remove the cooling fan assembly.
Remove clamp nut, and remove cooling fan assembly, distant pipe, and fan pulley.
7. Remove the crankshaft damper pulley.
8. Remove the timing gear case cover.
9. Remove the idler gear.
a. Measure the camshaft timing gear backlash and the crankshaft timing gear backlash before removing the idler gear.
b. Measure the idler gear end play before removing the idler gear.
LNWC1BSH006401
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NOTE:
Refer to the following items for details on the backlash and end play measurement procedures.
10. Timing Gear Backlash Measurement
a. Set a dial indicator to the timing gear to measured.
Hold both the gear to be checked and the adjoining gear stationary.
03 
b. Move the gear to be checked as far as possible to both the right and the left.
Take the dial indicator reading.
If the measured value exceeds the specified limit, the timing gear must be replaced.
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11. Idler Gear “A”End Play Measurement a. Insert a feeler gauge between the idler gear and the thrust collar to measure the gap and determine the idler gear end play.
b. If the measured value exceeds the specified limit, the thrust collar must be replaced.
12. Removeheidlegear.
13. Remove the fuel supply pump.
Refer to “Fuel Supply Pump”in Section 6C, Engine Fuel.
14. Remove the camshaft timing gear a. Use a dial indicator to measure the camshaft end play. This must be done before removing the camshaft gear.
If the camshaft end play exceeds the specified limit, the thrust plate must be replaced.
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b. Remove the camshaft timing gear bolt from the camshaft.
NOTE: Hold the camshaft stationary to prevent the camshaft from turning.
c. Use the universal puller (1) to pull out the camshaft timing gear (2).
Special tool: Universal Puller: 5-8521-0002-0d. Remove the thrust plate (3).
https://www.heavydutydiag.com/product/isuzu-linkone-epc-css-net-05-2020/
Use the crankshaft timing gear remover (1) to remove the crankshaft gear (2).
SST Crankshaft Timing Gear Remover: 5-8840-
2057-0
