This procedure covers removal and replacement of the intake manifold gasket on the 6.7L Cummins diesel engine, including removal of associated components and proper torque sequencing during reassembly.

Warnings

Tools required

Parts

• Intake manifold gasket × 1 — Use OEM specification
• Intake manifold bolt kit (if bolts show wear) × 1 — Use OEM specification
• EGR valve gasket × 1 — Use OEM specification
• Coolant crossover gasket × 1 — Use OEM specification
• PCV valve O-ring × 1 — Use OEM specification

Fluids

• Mopar OAT Coolant (Purple) — 2 qt

Preparation

1. Ensure engine is completely cool to the touch (minimum 2 hours after last operation).
2. Disconnect both negative and positive battery cables to prevent electrical issues during repair.
3. Remove engine cover by pulling upward on retaining clips.
4. Position coolant drain pan under radiator and open petcock to drain approximately 2 gallons of coolant from system.
5. Remove air intake system from throttle body to air filter housing.
6. Label all vacuum lines, electrical connectors, and hoses with tape or marker to ensure correct reinstallation.
7. Photograph wiring harness routing for reference during reassembly.

Procedure

1. 1

   Disconnect Electrical and Vacuum Connections
   Disconnect the main engine harness connector from the intake manifold. Disconnect all fuel injector electrical connectors by pressing the release tab and pulling straight up. Disconnect the intake air temperature sensor, manifold absolute pressure sensor, and any other sensors mounted to the intake manifold. Remove all vacuum lines connected to the intake manifold, noting their positions.
2. 2

   Remove Throttle Body
   Disconnect the throttle position sensor electrical connector. Remove the four throttle body mounting bolts and carefully lift the throttle body away from the intake manifold. Set aside with gasket. If gasket is damaged, replace during reassembly.
   Torque spec

   Throttle Body Bolts10 Nm (7 lb-ft)
3. 3

   Remove Fuel Rail Assembly
   Relieve fuel system pressure if not already dissipated from sitting. Disconnect fuel supply and return lines from the fuel rail using appropriate line disconnect tools. Remove fuel rail mounting bolts and carefully lift the fuel rail with injectors attached straight up and out of the cylinder head. Support the fuel rail assembly and place it aside on clean shop towels to prevent contamination.
   ⚠Diesel fuel may still be present in fuel rail. Have shop towels ready to catch spillage and prevent contamination of intake ports.
   Torque spec

   Fuel Rail Bolts12 Nm (9 lb-ft)
4. 4

   Remove EGR System Components
   If equipped with EGR, disconnect the EGR valve electrical connector. Remove the EGR valve mounting bolts and carefully remove the EGR valve from the intake manifold. Disconnect the EGR cooler outlet connection from the intake manifold. Remove coolant crossover tube mounting bolts if they obstruct intake manifold removal.
5. 5

   Remove PCV System Components
   Disconnect the PCV valve from the valve cover. Disconnect any PCV hoses or breather tubes connected to the intake manifold. Remove the PCV valve by carefully turning counterclockwise. Note the orientation for reinstallation.
6. 6

   Remove Additional Brackets and Hardware
   Remove any wiring harness brackets, ground straps, or support brackets attached to the intake manifold. Remove the intake manifold cover bolts if present. Check for any additional hoses or connections that may restrict manifold removal, including heater hoses or coolant bypass lines.
7. 7

   Remove Intake Manifold
   Remove all intake manifold mounting bolts in reverse order of the tightening sequence (outside to center pattern). Carefully break the gasket seal by gently prying at designated pry points only - do not pry between sealing surfaces. With assistance or using proper lifting technique, carefully lift the intake manifold straight up and away from the cylinder head. Be mindful of any remaining connections or obstructions.
   ⚠Intake manifold weighs approximately 40-50 lbs. Use proper lifting technique and consider having assistance to prevent dropping the manifold or causing injury.
   Torque spec

   Intake Manifold Bolts25 Nm (18 lb-ft)
8. 8

   Remove Old Gasket Material
   Use a plastic gasket scraper to carefully remove all old gasket material from both the intake manifold mating surface and the cylinder head surface. Work slowly and methodically to avoid gouging the aluminum surfaces. Clean any residual gasket material with brake cleaner and wipe dry with clean shop towels. Use compressed air to blow out intake ports and ensure no debris has fallen into the cylinders.
9. 9

   Inspect Mating Surfaces
   Carefully inspect both the intake manifold and cylinder head mating surfaces for any damage, warping, or deep scratches. Use a straight edge to check for warping if suspected. Minor surface imperfections are acceptable, but any deep gouges or warping may require machining or replacement. Inspect intake manifold bolt holes for debris and clean as needed. Cover open intake ports with clean shop towels to prevent debris entry.
   ℹ️Do not allow any debris, tools, or parts to fall into open intake ports as this will cause severe engine damage on startup.
10. 10

    Install New Gasket and Position Intake Manifold
    Remove protective covers from intake ports. Position the new intake manifold gasket onto the cylinder head, ensuring all ports and bolt holes align correctly. The gasket may have alignment pins or tabs to ensure proper orientation. Carefully lower the intake manifold onto the gasket, aligning all bolt holes. Thread all intake manifold bolts in by hand first to ensure proper thread engagement and alignment before tightening any bolts.
11. 11

    Torque Intake Manifold Bolts
    Using a torque wrench, tighten the intake manifold bolts to specification in the proper sequence, starting from the center bolts and working outward in a spiral pattern. Perform the tightening in two stages: first to 12 Nm (9 lb-ft) in sequence, then to final torque of 25 Nm (18 lb-ft) in the same sequence. This ensures even gasket compression and proper sealing.
    ⚠Critical: Follow center-to-outside torque sequence strictly. Improper sequence can cause gasket leaks or manifold warping.
    Torque spec

    Intake Manifold Bolts25 Nm (18 lb-ft)
12. 12

    Reinstall EGR and Coolant Components
    Install new EGR valve gasket and reinstall EGR valve if equipped. Torque EGR valve bolts to specification. Reinstall coolant crossover tube with new gasket if removed. Torque coolant crossover bolts to specification. Ensure all coolant passages are properly sealed.
13. 13

    Reinstall Fuel Rail Assembly
    Carefully position the fuel rail with injectors over the cylinder head, ensuring each injector aligns with its bore. Press down firmly and evenly on the fuel rail to seat all injectors fully into the cylinder head. Install fuel rail mounting bolts and torque to specification. Reconnect fuel supply and return lines, ensuring they click into place securely.
    Torque spec

    Fuel Rail Bolts12 Nm (9 lb-ft)
14. 14

    Reinstall Throttle Body and PCV System
    Install throttle body with new gasket if needed. Torque throttle body bolts to specification in a cross pattern. Install PCV valve with new O-ring, torquing to specification. Reconnect all PCV hoses and breather tubes. Reinstall any covers removed earlier and torque cover bolts to specification.
    Torque spec

    Throttle Body Bolts10 Nm (7 lb-ft)
15. 15

    Reconnect All Electrical and Mechanical Connections
    Reconnect all electrical connectors to sensors, injectors, and components in reverse order of removal using your labels and photos for reference. Ensure all connectors click securely into place. Reinstall all vacuum lines, wiring harness brackets, and ground straps. Reinstall air intake system from throttle body to air filter housing. Double-check that no connections have been missed.

Reassembly

1. Refill cooling system with Mopar OAT Purple coolant to proper level, bleeding air from system per manufacturer procedure.
2. Reconnect battery cables (positive first, then negative).
3. Reinstall engine cover.
4. Before starting engine, verify all tools and shop towels have been removed from engine compartment.

Verification

• With engine cold, start the vehicle and allow it to idle. Listen for any unusual vacuum leaks or hissing sounds around the intake manifold.
• Monitor engine temperature and coolant level during initial warm-up cycle. Check for coolant leaks around crossover connections.
• After engine reaches operating temperature, check for any vacuum leaks using a smoke machine or by listening carefully around all intake manifold joints.
• Verify smooth idle and normal throttle response with no hesitation or stumbling.
• After test drive, recheck all connection points and coolant level. Check for any fuel odor or visible leaks around fuel rail.
• Scan for diagnostic trouble codes to ensure all sensors are functioning properly and communicating with ECM.

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