How to Remove & Install Water Pump for ISUZU 4JJ1 Engine Truck

Here is a instruction show you guide on how to remove and install water pump for ISUZU engine 4JJ1 Euro 4 N-series truck.More about ISUZU truck case,please refer to ISUZU Trouble Repair.



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1.Drain the engine coolant.

2.Remove the fan guide.


3.Remove the fan guide bracket.

4.Remove the fan.

a.Loosen the fan clutch installation nut.

b.Remove the fan clutch together with the fan.

Take care not to damage the radiator.


5.Remove the generator drive belt and water pump pulley.

a.Loosen the generator mounting bolt and generator drive belt adjustment bolt.

b.Remove the generator drive belt and water pump pulley.

6.Remove the water pump assembly.

a.Remove the water pump installation nut and bolt.

b.Remove the water pump assembly and gasket.




1.Inspection of the bearing unit

Rotate the fan while pushing the fan center to the radius direction and inspect for any significant looseness or abnormal sounds.

When you find a problem, replace the water pump assembly.


2.External inspection

Inspect the pump body for cracks and damage.

Inspect the impeller for cracks and corrosion.

Inspect for water leaks from the seal unit.

When you find a problem, replace the water pump assembly.




1.Install the water pump assembly.

Install a new gasket, aligning it with the front cover stud.

Install the water pump by aligning to the front cover stud.

Tighten the installation bolt and nut at their specified torque.

Tightening torque:25 N-m (2.5kg-m/18 Ib-ft)


2.Install the water pump pulley and the fan with the fan clutch.

a.Take care not to damage the radiator when installing the fan together with the fan clutch.

b.Tighten the installation nut at the specified torque.

Tightening torque:8 Nm (0.8 kg-m/69 lbin)


3.Install the drive belt, and tighten the generator adjust bolts to adjust the tension of the belt.

4.After adjusting the drive belt, tighten the generator at the specified torque.

5.Install the fan guide bracket and tighten it at the specified torque.

Tightening torque: Left side and lower side:25 N-m (2.5kg-m/18 lb-ft)

Right side:51 N-M (5.2 kg-m/38 Ib-ft)

6.Install the fan guide.

Ensure a clearance of 3.0 mm(0.12 in) or more between the fan and the fan guide.


7.Refill the engine coolant.

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