Head Gaskets - Both

Complete cylinder head gasket replacement for the 5.9L Cummins diesel inline-6 engine, including removal and reinstallation of the single cylinder head.

Warnings

Tools required

Parts

• Cylinder head gasket × 1 — Use OEM Cummins specification
• Valve cover gasket × 1 — Use OEM specification
• Exhaust manifold gasket × 1 — Use OEM specification
• Intake manifold gasket set × 1 — Use OEM specification
• Thermostat housing gasket × 1 — Use OEM specification
• Injector O-ring set × 1 — Use OEM Cummins specification
• Injector copper crush washers × 6 — Use OEM specification
• Cylinder head bolts (complete set) × 1 — Use OEM Cummins torque-to-yield bolts
• Rocker lever assembly bolts × 1 — Use OEM specification if reusing
• Engine oil × 1 — 15W-40 diesel or 5W-40 synthetic
• Coolant filter (if equipped) × 1 — Use OEM specification

Fluids

• 15W-40 diesel oil or 5W-40 synthetic — 12 qt
• HOAT coolant 50/50 — 28 qt

Preparation

1. Park vehicle on level surface and engage parking brake
2. Disconnect both negative and positive battery cables
3. Drain engine coolant completely from radiator petcock and block drains
4. Drain engine oil and remove oil filter
5. Remove engine cover and air intake system from turbocharger to air filter housing
6. Remove intercooler tubes and charge air cooler connections
7. Label and photograph all electrical connections, vacuum lines, and fuel lines for reassembly reference
8. Support engine with hoist or fixture from overhead lifting eyes on engine block
9. Relieve fuel system pressure by loosening fuel filter drain valve

Procedure

1. 1

   Remove valve cover and accessory components
   Remove the valve cover by unbolting all perimeter bolts. Remove the fan shroud, viscous fan clutch assembly, and water pump pulley if necessary for access. Disconnect the power steering pump and bracket (support aside without disconnecting hoses). Remove alternator and mounting brackets as needed for cylinder head clearance.
2. 2

   Disconnect fuel system components
   For 24-valve common rail engines: disconnect high-pressure fuel rail from injectors and remove fuel rail assembly. Cap all openings immediately. For 12-valve P-pump engines: disconnect fuel lines from injection pump to injectors. Label each injector position. Disconnect fuel return lines and overflow valve connections. Use caps or plugs to prevent contamination entry.
3. 3

   Remove intake and exhaust manifolds
   Unbolt and remove the exhaust manifold, noting all retaining bolts per the service manual as the count varies with the multi-piece manifold design. On turbocharged models, disconnect turbocharger from exhaust manifold or remove as assembly. Remove intake manifold and intake horn assembly. Disconnect all remaining coolant hoses from thermostat housing and coolant crossover tube. Remove EGR components if equipped.
4. 4

   Remove rocker lever assembly
   Using a systematic pattern from outside bolts toward center, loosen all rocker lever pedestal bolts gradually (multiple passes) to prevent binding. Remove rocker shaft assembly as a complete unit. Keep pushrods in order by position - use a numbered holder or mark each one. Inspect pushrod ends and rocker components for wear.
5. 5

   Remove cylinder head bolts
   Remove cylinder head bolts in reverse order of tightening sequence (work from center outward in a crossing pattern). Since these are torque-to-yield bolts, they must be replaced and cannot be reused. If bolts are difficult to remove, apply penetrating oil and allow to soak. Check each bolt hole for coolant or oil indicating a potential breach.
6. 6

   Remove cylinder head
   With all bolts removed, carefully break the head seal using plastic pry points (avoid metal prying on sealing surfaces). Attach engine hoist to cylinder head lifting eyes. Lift head straight up to avoid damaging pistons or block surface. Place head on padded surface with valves facing up. Remove and keep track of dowel pins from block.
7. 7

   Clean and inspect cylinder head and block surfaces
   Thoroughly clean all gasket material from cylinder head and block deck surfaces using appropriate scrapers - avoid gouging the cast-iron sealing surfaces or using aggressive abrasive pads that could distort the deck. Clean bolt holes in block with brake cleaner and compressed air - any debris or oil will affect torque readings. Use straight edge and feeler gauges to check head and block for warpage - maximum allowable warpage is typically 0.002 inches per 6 inches. Check for cracks especially between valve seats and injector bores.
8. 8

   Inspect and service cylinder head components
   With head removed, inspect valve seats, valve guides, and valve faces. Check valve spring heights and pressures. Inspect injector bores for damage or carbon buildup. If head requires machining, take to qualified machine shop. Ensure the machine shop measures cylinder head thickness against the Cummins minimum thickness specification and does not resurface beyond the factory-allowed limit. Replace all valve stem seals if head is disassembled. Lap valves if necessary.
9. 9

   Prepare for cylinder head installation
   Verify block surface is completely clean and dry. Install new dowel pins if originals are damaged. Chase all head bolt threads in block with proper thread chaser to ensure accurate torque readings. Wipe bolt holes with clean shop towel. Do not use any sealers on head gasket - install dry. Position new head gasket on block with 'TOP' or 'UP' marking visible and oriented correctly for engine. Verify gasket alignment with dowel pins and all oil and coolant passages.
10. 10

    Install cylinder head
    Using engine hoist, carefully lower cylinder head onto block, aligning with dowel pins. Guide head into position without sliding it across gasket surface. Hand-thread all new cylinder head bolts to ensure they all start without cross-threading. Install bolts with light oil on threads and under bolt heads as specified in service manual.
11. 11

    Torque cylinder head bolts
    Without torque specifications in the database, follow the Cummins factory service manual torque sequence precisely. Follow the exact Cummins factory service manual head bolt torque-plus-angle sequence for the 2007 5.9L ISB common rail engine - do not rely on any generic step values; confirm each torque and angle stage directly from the manual. Always work from center outward in crossing pattern. Verify torque wrench calibration before beginning. Do not skip any steps or deviate from sequence.
12. 12

    Install pushrods and rocker assembly
    Install pushrods in their original positions, ensuring each seats properly in lifter socket. Apply assembly lube to rocker arm contact points and valve stem tips. Position rocker lever assembly onto pedestals. Install and hand-tighten all rocker shaft bolts. Torque rocker pedestal bolts to specification in sequence from center outward. Rotate engine by hand and verify all valves operate smoothly without binding.
13. 13

    Adjust valve lash
    Perform valve lash adjustment per Cummins specification using the appropriate method for your engine (12-valve or 24-valve). For 24-valve engines, verify the exact cold valve lash specification in the Cummins service manual (approximately 0.010 inches intake and 0.026 inches exhaust) before adjusting. Adjust valves with engine cold in firing order sequence, positioning each cylinder at TDC compression stroke. Use proper feeler gauges and lock adjustment screws securely after setting.
14. 14

    Install injectors and fuel system components
    Install new injector O-rings and copper crush washers on each injector. Lubricate O-rings with clean diesel fuel. Install injectors into cylinder head, ensuring proper seating. For common rail systems, install fuel rail and torque hold-down hardware to specification. For P-pump systems, reconnect fuel lines ensuring proper routing. Connect fuel return lines and overflow valve. Double-check all connections are tight and properly secured.
15. 15

    Reinstall manifolds and remaining components
    Install new intake manifold gaskets and reinstall intake manifold and horn assembly. Install new exhaust manifold gasket and reinstall exhaust manifold (torque in sequence from center outward). Reconnect turbocharger if previously separated. Reinstall all coolant hoses and thermostat housing with new gasket. Install valve cover with new gasket. Reinstall alternator, power steering pump, and all brackets. Reinstall serpentine belt system, fan assembly, and shroud. Reconnect all electrical connections and sensors per documentation from disassembly.

Reassembly

1. Verify all fasteners are properly torqued and no connections were missed
2. Refill cooling system with proper 50/50 HOAT coolant mixture - use coolant fill and bleed procedure to eliminate air pockets
3. Install new oil filter and refill engine with 12 quarts of appropriate diesel engine oil
4. Reconnect both battery cables (positive first, then negative)
5. Prime fuel system using lift pump or manual primer until firm resistance is felt
6. For common rail systems, cycle ignition key several times without starting to allow fuel system to pressurize

Verification

• Perform initial start and allow engine to idle - monitor for unusual noises, vibrations, or leaks
• Check for fuel leaks at all injector connections and fuel rail while engine is running
• Monitor coolant level and temperature - watch for overheating or coolant loss
• Check for oil leaks at valve cover and any disturbed oil system components
• After engine reaches operating temperature, shut down and allow to cool, then recheck coolant level and add if necessary
• Perform a test drive monitoring engine temperature, oil pressure, and turbo boost levels
• After 500 miles, re-check valve lash adjustment and torque valve cover bolts
• Change oil and filter after first 500 miles to remove any assembly debris

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