Intake Manifold

This procedure covers the removal and replacement of the intake manifold on a 2007 Ram 3500 with the 5.9L Cummins diesel engine, including disconnection of all related sensors, hoses, and the intake grid heater assembly.

Warnings

Tools required

Parts

• Intake manifold gasket × 1 — Use OEM specification
• Intake grid heater gasket × 1 — Use OEM specification
• Intake manifold bolts (if damaged) × 1 — Use OEM specification
• Hose clamps (if damaged) × 1 — Various sizes

Preparation

1. Park vehicle on level ground and engage parking brake
2. Allow engine to cool completely for at least 2 hours
3. Disconnect both battery cables, negative first, then positive
4. Remove engine cover if equipped
5. Take photographs of all hose and electrical connections for reference during reassembly

Procedure

1. 1

   Disconnect air intake system
   Loosen the clamp securing the air intake tube to the turbocharger inlet. Remove the intake tube and air filter housing assembly. Disconnect the crankcase breather hose from the intake tube. Set these components aside in a clean area.
2. 2

   Disconnect electrical connections
   Locate and disconnect the intake air temperature (IAT) sensor connector on the intake manifold. Disconnect the intake grid heater electrical connectors (two large terminals on top of the intake manifold). These terminals are secured with nuts and require careful removal to avoid damaging the terminals.
3. 3

   Remove intake grid heater
   Remove the bolts securing the intake grid heater to the top of the intake manifold (typically 6-8 bolts around the perimeter). Carefully lift the grid heater assembly straight up and off the manifold. Note the gasket position and condition. Inspect the grid heater element for damage or cracks.
4. 4

   Disconnect turbocharger inlet connection
   Locate the charge-air (intercooler) tube connection to the intake manifold air horn. Loosen the clamp securing this connection and carefully separate the intake tube from the manifold inlet, taking care not to damage the mating surfaces. You may need to gently rock the connection to break it free.
5. 5

   Disconnect vacuum and breather lines
   This diesel engine does not use a vacuum brake booster (it uses hydro-boost), and there are no vacuum HVAC or EGR lines on the intake manifold. Disconnect the crankcase vent tube from the intake manifold and label the connection for reassembly. Disconnect the crankcase vent tube from the intake manifold. Label each connection or refer to your photographs for reassembly.
6. 6

   Remove throttle linkage connections
   This diesel engine has no throttle body, throttle position sensor, or throttle linkage on the intake manifold (fueling is electronically controlled via the accelerator pedal sensor). Skip this step; there are no throttle connections to remove.
7. 7

   Remove intake manifold mounting bolts
   Locate all intake manifold mounting bolts securing the manifold to the cylinder head (typically 8-10 bolts). Begin loosening the bolts in a criss-cross pattern, working from the outer bolts toward the center. Remove all bolts completely and store them in a clean container. Note the location of any bolts that may be different lengths.
8. 8

   Remove intake manifold
   Carefully lift the intake manifold straight up and away from the cylinder head. The manifold may be stuck to the gasket, so gentle rocking may be necessary. Do not pry against the aluminum mating surfaces. Once free, remove the manifold completely and set aside on a clean work surface.
9. 9

   Clean mating surfaces
   Remove the old gasket/seal from both the manifold and cylinder head surfaces. Use a plastic scraper and clean rag to carefully clean the mating surfaces on the cast-iron cylinder head and manifold, taking care not to gouge or scratch them. Wipe clean with shop towels. Inspect both surfaces for cracks, warping, or damage. Stuff clean shop towels into the intake ports of the cylinder head to prevent debris from entering.
10. 10

    Install new gasket and manifold
    Remove the shop towels from the intake ports. Position the new intake manifold gasket on the cylinder head, ensuring proper alignment with all intake ports and bolt holes. Carefully lower the intake manifold onto the gasket, aligning all bolt holes. Hand-thread all mounting bolts to ensure proper alignment before tightening.
11. 11

    Torque intake manifold bolts
    Tighten the intake manifold mounting bolts in a criss-cross pattern, working from the center outward. Follow the manufacturer's torque specification sequence if available. Since specific torque values are not provided in the database, consult a factory service manual or torque specification chart. Consult the factory service manual for the exact Cummins ISB 5.9L torque specification and sequence; do not rely on generic values, as intake/grid heater fastener torques must match Cummins documentation.
12. 12

    Reconnect turbocharger connection
    Reconnect the turbocharger outlet to the intake manifold inlet. Install the V-band clamp or mounting bolts and tighten securely. Ensure proper alignment to avoid air leaks in the intake system.
13. 13

    Install intake grid heater
    Position the new grid heater gasket on the intake manifold surface. Carefully lower the intake grid heater assembly onto the manifold, aligning all bolt holes. Install all mounting bolts and tighten in a criss-cross pattern to ensure even seating. Reconnect both electrical terminals to the grid heater, ensuring clean, tight connections.
14. 14

    Reconnect all sensors and lines
    Reconnect the IAT sensor electrical connector. Reattach all vacuum lines, breather hoses, and throttle linkage connections in their original positions using your photographs as reference. Ensure all hose clamps are tight and all connections are secure.
15. 15

    Reinstall air intake system
    Reinstall the air intake tube and air filter housing assembly. Connect the crankcase breather hose. Tighten the clamp at the turbocharger inlet connection securely. Ensure the entire air intake path is properly sealed with no loose connections.

Reassembly

1. Reconnect battery cables (positive first, then negative)
2. Reinstall engine cover if equipped
3. Double-check all electrical connections and hose clamps for security
4. Verify no tools or shop towels were left in the engine compartment

Verification

• Start the engine and listen for any unusual hissing or air leak sounds from the intake manifold area
• Allow the engine to reach operating temperature and verify smooth idle with no misfires or rough running
• Check for air leaks around all intake connections using soapy water or by listening carefully
• Verify the intake grid heater is functioning by checking for a momentary delay before the engine starts (grid heater cycle)
• Test drive the vehicle to ensure normal power delivery and no check engine lights
• Perform a visual inspection after the test drive to verify no leaks or loose connections have developed

Related trouble codes on this vehicle

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