Isuzu 6HK1 Generator Set

⚠ Adjust valve clearance carefully so that the bridge may become level (hit the end of the 2 valve axes).

⚠ If the bridge adjusting screw is poorly adjusted, the bridge may tilt, be pushed down and seize, damaging the bridge guide.

Tools: 0.4 mm thickness gauge, flathead screwdriver

1. Loosen all bridge and rocker arm adjusting nuts and screws (4HK1: 8 nuts/8 screws, 6HK1: 12 nuts/12 screws).
2. Place a 0.4 mm thickness gauge between the No.1 cylinder rocker arm end and bridge cap.
3. Tighten rocker arm adjusting screw until the gauge is snug between rocker arm end and bridge cap.
4. Tighten the rocker arm lock nut.
5. Tighten the bridge adjusting screw until the bridge contacts the valve head.
6. Tighten the bridge lock nut.
7. Check the thickness gauge is still held snugly; if too tight loosen bridge screw and nut.
8. Remove the thickness gauge and repeat for remaining cylinders.

⚠ Adjust while cold.

⚠ Ensure bridge is level and hits both valve axis ends.

⚠ Avoid seizing bridge guide.

Tools: 0.4 mm thickness gauge, wrenches, screwdriver

1. Remove cylinder head cover and fuel injector harness ASM.
2. Remove leak off pipe and rotate crankshaft to No.1 cylinder compression TDC.
3. Insert 0.4 mm thickness gauge between rocker arm and bridge to check clearance.
4. Loosen all bridge and rocker arm adjusting nuts and screws (4HK1: 8 nuts/8 screws; 6HK1: 12 nuts/12 screws).
5. Place 0.4 mm thickness gauge between No.1 cylinder rocker arm end and bridge cap.
6. Tighten rocker arm adjusting screw until gauge is snug, then tighten lock nut.
7. Tighten bridge adjusting screw until bridge contacts valve head, then tighten lock nut.
8. Check gauge snugness; adjust if too tight.
9. Remove gauge and repeat for remaining cylinders.

⚠ Clear ECM memory after measurement because DTC is recorded when harness connector is removed.

Tools: Compression gauge 5-8840-2675-0 (J-26999-12), Compression gauge adapter EN-46722 (4HK1), Compression gauge adapter 5-8840-2622-0 (6HK1)

1. Warm up engine.
2. Remove negative battery terminal and all glow plugs.
3. Disconnect fuel injector harness connector (no fuel injected).
4. Install compression gauge adapter and gauge (4HK1: EN-46722; 6HK1: 5-8840-2622-0; gauge: 5-8840-2675-0/J-26999-12).
5. Turn starter and measure each cylinder; keep engine speed at 200 rpm or more.
6. Remove gauge, reconnect harness, install glow plugs, reconnect battery.

⚠ Adjust while being cold.

Tools: 0.4 mm thickness gauge

1. Remove the cylinder head cover.
2. Remove the fuel injector harness ASM by loosening the terminal nuts alternately.
3. Remove the leak off pipe.
4. Rotate the crankshaft so No.1 cylinder is at compression TDC.
5. Insert a 0.4 mm thickness gauge between rocker arm and bridge to check clearance.

⚠ Push connector thoroughly until claws raise.

Tools: torque wrench

1. Install gasket on lower cover.
2. Install head cover case.
3. Install fuel injector harness connector; push until claws lock.
4. Install gasket on head cover.
5. Install head cover and tighten in order.

Tools: hand tools

1. Remove head cover.
2. Remove gasket.
3. Remove fuel injector harness connector.
4. Remove head cover case.
5. Remove gasket.

⚠ Tighten bolt indicated with arrow.

⚠ Tighten stud part together with common rail.

⚠ Install within 7 minutes.

Tools: liquid gasket, torque wrench

1. Apply liquid gasket (ThreeBond 1207C or equivalent) bead diameter 2.5-5.5 mm along groove.
2. Install within 7 minutes after applying liquid gasket.
3. Install case ASM.
4. Install gasket on inlet pipe and tighten.
5. Install common rail.

⚠ Do not forget bolt inside inlet cover.

Tools: hand tools

1. Remove common rail.
2. Remove inlet pipe.
3. Remove case ASM.
4. Remove inlet cover (be careful of bolt inside).
5. Peel liquid gasket off carefully.

⚠ Do not over-tighten exhaust manifold to allow heat expansion.

Tools: torque wrench

1. Put gasket in and install exhaust manifold; tighten nuts/bolts in order (4HK1: 2 nuts/6 bolts; 6HK1: 12 nuts).
2. Install gasket and turbocharger to exhaust manifold; tighten nuts.
3. Tighten adapter bolts (exhaust manifold side).
4. Install water feed pipe to turbocharger (4HK1 only); tighten joint bolts.
5. Install pipe bracket and tighten bolts.

Tools: hand tools

1. Drain coolant (4HK1 only).
2. Remove air intake duct from turbocharger and air cleaner.
3. Remove charge air pipe from turbocharger and charge air cooler.
4. Disconnect front exhaust pipe.
5. Remove EGR pipe.
6. Remove oil feed pipe and oil return pipe.
7. Remove water feed pipe and water return pipe (4HK1 only).
8. Remove heat protector.
9. Remove exhaust adapter bolts.
10. Remove four turbocharger clamping nuts.
11. Remove turbocharger from exhaust manifold.
12. Remove exhaust manifold.