Head Gasket - Single

Complete cylinder head gasket replacement for the 5.9L Cummins I6 diesel engine, including cylinder head removal, inspection, surface preparation, and installation with new head gasket and bolts.

Warnings

Tools required

Parts

• Cylinder head gasket kit × 1 — Use OEM Cummins specification
• Cylinder head bolts (TTY) × 1 — Use OEM Cummins - Set of 12
• Valve cover gasket × 1 — Use OEM specification
• Exhaust manifold gasket × 1 — Use OEM specification
• Intake manifold gasket × 1 — Use OEM specification
• Fuel injector O-rings and seals × 1 — Set of 6
• Thermostat housing gasket × 1 — Use OEM specification
• Water pump bypass tube O-ring × 1 — Use OEM specification
• Anti-seize compound × 1 — High-temperature nickel-based

Fluids

• 15W-40 diesel engine oil — 12 qt
• Ethylene glycol 50/50 coolant — 28 qt

Preparation

1. Disconnect both battery cables, negative first
2. Drain engine coolant completely from radiator and block drain plugs
3. Drain engine oil and replace oil filter
4. Remove engine cover and air intake system from turbocharger to air cleaner
5. Label and photograph all electrical connections and hose routing before removal
6. Relieve fuel system pressure by loosening fuel filter drain valve
7. Place vehicle on level ground with parking brake engaged and wheel chocks in place
8. Remove intercooler and charge air piping if equipped
9. Support engine weight with hoist or engine support fixture

Procedure

1. 1

   Remove Valve Cover and Accessories
   Remove valve cover bolts in reverse order from outside to inside. Disconnect all electrical connectors from injectors, grid heater, and sensors. Remove alternator, power steering pump (leave hoses attached and secure aside), and A/C compressor (leave hoses attached). Tag all connections for reassembly.
2. 2

   Disconnect Fuel System
   Disconnect fuel supply and return lines from fuel filter housing. Remove high-pressure fuel lines from each injector using proper line wrenches - loosen at injector end first, then at pump end. Cap all openings immediately to prevent contamination. Remove fuel filter housing assembly if it obstructs access.
3. 3

   Remove Exhaust Manifold
   Disconnect exhaust pipe from turbocharger or manifold outlet. Remove turbocharger if necessary for access. Remove all exhaust manifold mounting nuts and carefully remove manifold. Inspect studs for damage and replace if necessary.
4. 4

   Remove Intake Manifold
   Disconnect all vacuum lines, breather hoses, and heater hoses from intake manifold. Remove intake manifold grid heater wiring. Remove intake manifold mounting bolts in reverse sequence from outside to inside. Lift intake manifold from cylinder head and set aside. Cover intake ports with clean shop towels.
5. 5

   Remove Rocker Arm Assembly
   Loosen rocker arm shaft bolts evenly in multiple passes from center outward to prevent bending the shaft. Remove rocker arm assembly as a complete unit and set on clean surface. Keep pushrods in order - mark or use a holder to maintain position. Inspect pushrod ends for wear.
6. 6

   Remove Fuel Injectors
   Using injector puller tool, carefully remove each fuel injector from cylinder head. Rock injector gently while pulling to break seal. Inspect injector bores for damage or carbon buildup. Cover cylinder openings immediately with clean shop towels to prevent debris entry.
7. 7

   Remove Cylinder Head Bolts
   Remove cylinder head bolts in reverse of tightening sequence (outside to inside pattern). Loosen each bolt 1/4 turn in sequence, then repeat until all are loose before complete removal. Discard all head bolts - they are torque-to-yield and must be replaced. Keep bolts in order to verify all 12 are removed.
8. 8

   Remove Cylinder Head
   With hoist or assistant support, carefully break head free from block using plastic pry points only (never between gasket surfaces). Lift cylinder head straight up to avoid damaging block surface. Place cylinder head on clean padded surface with combustion chamber side up. Immediately cover open cylinders in block with clean towels.
9. 9

   Clean and Inspect Surfaces
   Remove all old gasket material from both cylinder head and block surfaces using plastic scraper only - never metal tools. Clean surfaces thoroughly with brake cleaner. Use straight edge and feeler gauge to check head and block for warpage - maximum allowable warpage is 0.004 inches. Check for cracks in combustion chambers and between valve seats. Inspect cylinder head bolt holes in block - chase threads if necessary and ensure holes are dry and clean.
10. 10

    Install New Head Gasket
    Verify block and head surfaces are completely clean and dry. Install new cylinder head gasket on block with 'TOP' or 'FRONT' marking visible and oriented correctly. Align gasket dowel pins. Do NOT use any sealant on head gasket. Verify coolant and oil passages align correctly.
11. 11

    Install Cylinder Head
    With hoist support, carefully lower cylinder head onto block, aligning with dowel pins. Guide head straight down - do not slide across gasket surface. Ensure head seats completely on gasket. Install NEW cylinder head bolts finger-tight in sequence from center outward. Apply light oil to bolt threads and under bolt heads before installation.
12. 12

    Torque Cylinder Head Bolts
    Torque cylinder head bolts following the manufacturer sequence: Step 1 - torque all bolts to 30 ft-lb in proper sequence. Step 2 - torque all bolts to 60 ft-lb in sequence. Step 3 - rotate each bolt an additional 90 degrees in sequence using angle gauge. Verify exact specification against your specific engine variant (12-valve vs 24-valve). Allow no interruptions during torque sequence - complete all steps without stopping. - complete all steps without stopping.
    Torque spec

    Cylinder Head Bolts - Step 140 Nm (30 lb-ft)

    Cylinder Head Bolts - Step 280 Nm (59 lb-ft)

    Cylinder Head Bolts - Step 30 Nm (0 lb-ft) + 90°

    Cylinder Head Bolts - Step 40 Nm (0 lb-ft) + 90°
13. 13

    Install Fuel Injectors and Rocker Assembly
    Install new O-rings and copper seals on each fuel injector. Lubricate O-rings with clean diesel fuel. Install injectors into bores - should seat with firm hand pressure. Install pushrods in original positions. Install rocker arm assembly and tighten shaft bolts evenly from center outward in multiple passes to final torque. Verify all rocker arms move freely and contact pushrod ends properly.
14. 14

    Install Intake and Exhaust Manifolds
    Install new intake manifold gasket. Position intake manifold and install bolts finger-tight. Torque intake manifold bolts to specification in sequence from center outward. Apply anti-seize compound to exhaust manifold studs. Install new exhaust manifold gasket and position manifold. Install and torque exhaust manifold nuts to specification.
    Torque spec

    Intake Manifold Bolt25 Nm (18 lb-ft)

    Exhaust Manifold Nuts25 Nm (18 lb-ft)
15. 15

    Reconnect Fuel System and Accessories
    Reconnect high-pressure fuel lines to injectors and fuel pump. Torque fuel line fittings to specification using proper line wrenches. Install fuel supply and return lines. Reinstall all accessories including alternator, power steering pump, A/C compressor, and turbocharger if removed. Reconnect all electrical connections to injectors and sensors per photos/labels.
16. 16

    Install Valve Cover and Final Assembly
    Install new valve cover gasket. Position valve cover and install bolts, tightening in sequence from center outward. Reconnect all breather hoses and electrical connections. Install intercooler and charge air piping. Reinstall air intake system. Reconnect battery cables, positive first.

Reassembly

1. Double-check all electrical connectors are properly seated and locked
2. Verify all fuel line connections are tight and properly torqued
3. Ensure no tools or rags remain in engine compartment
4. Verify all hoses and wiring are routed correctly and secured with proper clips

Verification

• Refill cooling system with proper 50/50 coolant mixture and bleed air from system using bleeder valves
• Refill engine with 12 quarts of 15W-40 diesel engine oil and new filter
• Cycle ignition key several times without starting to prime fuel system
• Start engine and verify no fuel, oil, or coolant leaks - check all connection points
• Allow engine to reach operating temperature and verify cooling fan operation
• Check for exhaust leaks at manifold connections while engine is running
• Verify proper oil pressure on gauge (minimum 10 psi at idle when warm)
• Check coolant level after engine cools and top off if necessary
• Road test vehicle under various load conditions to verify proper operation and no overheating

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