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SERIES 638 OVERVIEW OF EXHAUST SYSTEM

The exhaust system consists of a three-piece exhaust manifold. For a typical configuration of the exhaust system and gaskets, see Figure 28600 . ‪

The outlet flange is centrally located and connects directly to the turbocharger turbine housing. ‪

The three pieces of the exhaust manifold incorporate metallic seal rings and slip joints which slide together easily on initial assembly, and seal when the manifold is heated by engine operation. See Figure 28600 for parts location. ‪

1.Stud ‪

7.Exhaust Manifold ‪

2.Gasket ‪

8.Metallic Seals ‪

3.Exhaust Manifold Rear ‪

9.Exhaust Manifold ‪

4.Heat Shield ‪

10.Nut ‪

5.Washer ‪

11.Lifting Eye ‪

6.Bolt ‪

Exhaust Manifold and Related Parts

Repair or Replacement of Exhaust Manifold

To determine if repair or replacement of the exhaust manifold is necessary perform, the following procedure. See Figure 28596 . ‪

Flowchart for Repair or Replacement of Exhaust Manifold

Removal of Exhaust Manifold

Remove the exhaust manifold as follows: ‪

  1. Remove the turbocharger. Refer to section .
  2. Remove three screws securing the exhaust manifold heat shield to the exhaust manifold. See Figure 28600 .

    1.Stud ‪

    7.Exhaust Manifold ‪

    2.Gasket ‪

    8.Metallic Seals ‪

    3.Exhaust Manifold Rear ‪

    9.Exhaust Manifold ‪

    4.Heat Shield ‪

    10.Nut ‪

    5.Washer ‪

    11.Lifting Eye ‪

    6.Bolt ‪

    Removal of Exhaust Manifold

  3. Remove the exhaust heat shield from the exhaust manifold.
  4. Remove twelve nuts securing the exhaust manifold to the cylinder block. See Figure 28600 .

    To avoid personal injury when removing the exhaust manifold assembly, use care to ensure that the assembly is removed as a unit. ‪

    Before removing the exhaust manifold, wait until the engine has cooled. The exhaust manifold and other engine components may be extremely hot and may cause burns and other personal injury. ‪

  5. Remove the exhaust manifold and gaskets.
  6. Disassemble the exhaust manifold for cleaning and inspection.
Cleaning of Exhaust Manifold

Clean the exhaust manifold as follows: ‪

  1. Remove any loose scale and carbon that may have accumulated on the internal walls of the manifold.

    To prevent possible personal injury during this operation, adequate eye protection must be worn. ‪

  2. Clean the exhaust manifold exterior with a wire brush.
Inspection of Exhaust Manifold

Inspect the exhaust manifold as follows: ‪

  1. Visually check the exhaust manifold sections for cracks.
    1. If the exhaust manifold is cracked, replace the component. Refer to section .
    2. If the exhaust manifold is not cracked, proceed with step of inspection.
  2. Visually check the exhaust manifold bolts for elongation.
    1. If the exhaust manifold bolts are elongated, replace the component. Refer to section .
    2. If the exhaust manifold bolts are not elongated, proceed with step of inspection.
  3. Visually check the exhaust manifold metallic seals for breakage or damage.
    1. If the exhaust manifold metallic seals are broken or damaged, replace the components. Refer to section .
    2. If the exhaust manifold metallic seals are not broken or damaged, proceed with step of inspection.
  4. Visually check the exhaust manifold for leakage.
    1. If the exhaust manifold has leaked, replace the component. Refer to section .
    2. If the exhaust manifold has not leaked, reuse the component. Refer to section .

Installation of Exhaust Manifold

Install the exhaust manifold as follows: ‪

  1. Assemble the exhaust manifold as follows:
    1. Place the metallic seals into the exhaust manifold slip joints. See Figure 28600 .
    2. Assemble exhaust manifold sections.
    3. 1.Stud ‪

      7.Exhaust Manifold ‪

      2.Gasket ‪

      8.Metallic Seals ‪

      3.Exhaust Manifold Rear ‪

      9.Exhaust Manifold ‪

      4.Heat Shield ‪

      10.Nut ‪

      5.Washer ‪

      11.Lifting Eye ‪

      6.Bolt ‪

      Exhaust Manifold Assembly

  2. Install the exhaust manifold and gaskets to the cylinder block and secure with twelve nuts. Torque nuts to 31-33 N m (23-24 lb ft). See Figure 28600 .

    1.Stud ‪

    7.Exhaust Manifold ‪

    2.Gasket ‪

    8.Metallic Seals ‪

    3.Exhaust Manifold Rear ‪

    9.Exhaust Manifold ‪

    4.Heat Shield ‪

    10.Nut ‪

    5.Washer ‪

    11.Lifting Eye ‪

    6.Bolt ‪

    Installation of Exhaust Manifold

  3. Install the heat shield to the exhaust manifold and tighten bolts. Torque bolts to 8-10 N m (6-7 lb ft).
  4. Install the turbocharger assembly. Refer to section .
  5. Run the engine to verify repair.