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MBE 900 CYLINDER HEAD

The single-piece cylinder head is made of cast iron. The cylinder head gasket is a three-layer, adjustment-free seal with Viton sealing elements. ‪

Cylinder Head Removal

Remove cylinder head as follows: ‪

PERSONAL INJURY

To avoid injury from scalding, drain the radiator when the engine and coolant are cool.

  1. Drain the coolant from the radiator.
  2. Remove the coolant delivery hoses from the surge tank. See Figure 42213 .

    1. Drain Hose ‪

    4. Hose from Radiator ‪

    2. Overflow Hose ‪

    5. Surge Tank ‪

    3. Hose from Engine ‪

    Coolant Hoses at the Surge Tank

  3. Remove the coolant hose standoff bracket.
  4. Remove the air cleaner, charge-air inlet, and turbocharger outlet pipes and hoses. See Figure 42214 .

    1. Air Cleaner Pipe ‪

    3. Intake Manifold Inlet Pipe ‪

    2. Turbocharger Outlet Pipe ‪

    4. Crankcase Breather Hose (closed crankcase shown) ‪

    Charge-Air Pipes and Hoses

  5. Remove the air cleaner assembly.
  6. Remove the engine trim panel.

    Note: Clean the cylinder head cover before removing it.

  7. Remove the cylinder head cover. Refer to section .
  8. Remove the sensor cover and disconnect the intake manifold pressure/temperature sensor.
  9. Remove the charge-air manifold and gasket. See Figure 42210 .

    1. Charge-Air Manifold ‪

    7. Coolant Temperature Sensor ‪

    2. Rocker Arm Assembly ‪

    8. Water Pump Connector Fitting ‪

    3. Valve Bridge ‪

    9. Coolant Line ‪

    4. Pushrod ‪

    10. Front Connector Housing ‪

    5. High Pressure Fuel Injection Line ‪

    11. Gasket ‪

    6. Engine Wiring Harness/Connector ‪

    Cylinder Head Exposed

  10. Disconnect the turbocharger oil inlet line.
  11. Remove the exhaust brake cylinder and heat shield.
  12. Using the exhaust manifold socket set J-46379 , remove the exhaust manifold bolts.

    Note: Use the short socket for the rearmost bolt. Use the long socket for the other bolts.

  13. Pull the exhaust manifold away from the engine towards the frame rail and remove the gaskets.
  14. Remove the front connector housing assembly.
    1. Disconnect the temperature sensor from the engine wiring harness connector.
    2. Disconnect the coolant line.
    3. Remove the front connector housing and gasket from the cylinder head.
    4. Remove the water pump connector fitting from the water pump.
  15. Remove the rocker arm assembly. Mark the pushrods in order of removal.
  16. Remove the valve bridges. Mark the valve bridges in order of removal.

    NOTICE:

    Do not move the thrust bolt, because there is danger of causing a change in the position of the transfer tube within the cylinder head. If the position of the fuel transfer tube is changed, engine damage could result. ‪

  17. Using two wrenches, loosen the high pressure line fittings. The procedure that follows will need to be performed on each high pressure line fitting.

    1. Thrust Bolt ‪

    4. Unit Pump ‪

    2. High Pressure Line Fitting ‪

    5. Open-Ended Wrenches ‪

    3. Transfer Tube Line ‪

    High Pressure Line Fittings

    1. Using a paint pen, mark the location of the thrust bolt.
    2. Place one wrench on the thrust bolt to secure the transfer tube. Place the other wrench on the high pressure line fitting.
    3. Turn the wrench on the high pressure line fitting while holding the other wrench on the thrust bolt.
  18. Remove the high pressure injection line from the head and unit pump.
  19. To prevent any dirt from entering, cover the openings in the unit pump and the transfer tube.
  20. Remove the heater hose from the back of the cylinder head.
  21. Disconnect the fuel return line from the cylinder head.
  22. Remove the constant-throttle valve line.
  23. Disconnect the coolant delivery line from the cylinder head to the air compressor.
  24. Using the head bolt impact socket J-45390 , remove the cylinder head bolts.

    NOTICE:

    Do not place the head mating surface down on a flat surface. This would damage the injection nozzles, which protrude slightly. ‪

  25. Attach the cylinder head lifting device J-46387 .
  26. Remove the cylinder head, see Figure 42211 , and set it on wooden blocks or on its side.

    1. Cylinder Head ‪

    6. Cylinder Head Gasket ‪

    2. Cylinder Head Bolt ‪

    7. Constant Throttle Valve Line ‪

    3. Intake Manifold Pressure/Temperature Sensor ‪

    8. Coolant Delivery Line ‪

    4. Lifting Eye ‪

    9. Alignment Pin ‪

    5. Heater Hose ‪

    10. Fuel Return Line ‪

    Cylinder Head Removed

  27. Remove the head gasket.
  28. Thoroughly clean the cylinder head and head mating surface of excess oil, grime, and paint chips.
  29. With a straightedge, check the cylinder head surface for warpage. The warpage limits on the 6-cylinder engine are listed in Table and the allowable warpage limits on the 4-cylinder engine are listed in Table .

    Description ‪

    Limit ‪

    Over entire length ‪

    0.07 mm (0.003 in.) ‪

    Over a length of 150 mm (6 in.) ‪

    0.02 mm (0.001 in.) ‪

    Head Warpage Limits, 6-Cylinder Engine

    Description ‪

    Limit ‪

    Over entire length ‪

    0.05 mm (0.002 in.) ‪

    Over a length of 150 mm (6 in.) ‪

    0.02 mm (0.001 in.) ‪

    Head Warpage Limits, 4-Cylinder Engine
  30. With a straightedge, check the cylinder block mating surface for warpage. The cylinder block warpage is listed in Table .

    Description ‪

    Limit ‪

    Over entire length ‪

    0.030 mm (0.0012 in.) ‪

    Over a length of 150 mm (6 in.) ‪

    0.015 mm (0.0006 in.) ‪

    Cylinder Block Warpage Limits, 4- and 6-Cylinder Engines
  31. Inspect the cylinder head for cracks or signs of damage. Replace if necessary.

Cylinder Head Installation

Install the cylinder head as follows: ‪

  1. Install a new head gasket.
  2. Lower the cylinder head back into place. Remove the cylinder head lifting device.
  3. Using a dial caliper, measure the length of the cylinder head bolts from the end of the bolt to the bottom of the flange. See Figure 41874 . The acceptable bolt length is listed in Table .

    1. Dial Caliper ‪

    3. Bottom of Flange ‪

    2. End of Cylinder Head Bolt ‪

    Measuring Head Bolts

    Description ‪

    Length ‪

    Shaft length when new ‪

    149.0 mm (5.87 in.) ‪

    Maximum shaft length ‪

    151.0 mm (5.94 in.) ‪

    Cylinder Head Bolts, Length
  4. Lubricate the cylinder head bolts with engine oil.
  5. Using the head bolt impact socket J 45390 , install the cylinder head bolts. The specific stages in the tightening sequence are listed in Table . See Figure 42216 for the torque sequence on the 6-cylinder engine and see Figure 42217 for the torque sequence on the 4-cylinder engine.

    Size ‪

    Max. Shaft Length ‪

    Tightening Stage ‪

    Torque Values ‪

    M16 ‪

    151.0 mm (5.94 inches) ‪

    Stage 1 ‪

    20 Nm (15 lbft) ‪

    Stage 2 ‪

    70 Nm (52 lbft) ‪

    Stage 3 ‪

    170 Nm (125 lbft) ‪

    Stage 4 ‪

    280 Nm (207 lbft) ‪

    Stage 5 ‪

    additional 90 degrees ‪

    Stage 6 ‪

    additional 90 degrees ‪

    Tightening Stages, Cylinder Head

    Tightening Sequence, 6-Cylinder Engine

    Tightening Sequence, 4-Cylinder Engine

  6. Connect the coolant delivery line from the cylinder head to the air compressor.
  7. Replace the seal and connect the fuel return line to the cylinder head.
  8. Replace the seal and install the constant-throttle valve supply line.
  9. Install the heater hose to the back of the cylinder head.

    NOTICE:

    Correct torque on the high pressure fuel lines is critical. Incorrect torques could result in leaks or lack of power due to restricted fuel flow. ‪

  10. Without turning the transfer tube thrust bolts, install the high pressure fuel injection lines in the as-removed positions.
    1. Tighten the high pressure fuel injection line fittings 25 Nm (18 lbft).
  11. Install new exhaust manifold gaskets.
  12. Using the exhaust manifold socket set J-46379 , install the exhaust manifold bolts.

    Note: Use the short socket for the rearmost bolt. Use the long socket for the other bolts.

  13. Install the exhaust manifold and tighten the bolts. The specific torque stages and values are listed in Table .

    Size ‪

    Maximum Shaft Length ‪

    Tightening Stage ‪

    Torque Value ‪

    M10 ‪

    47.5 mm (1.87 in.) ‪

    Stage 1 ‪

    10 Nm (7 lbft) ‪

    Stage 2 ‪

    55 Nm (41 lbft) ‪

    Stage 3 ‪

    additional 90 degrees ‪

    Tightening Stages, Exhaust Manifold Bolts
  14. Install the exhaust brake cylinder and heat shield.
  15. Using new gaskets, install the charge-air manifold. Tighten the fasteners to 25 Nm (18 lbft).
  16. Connect the charge-air pressure/temperature sensor to the back of the charge-air manifold. Install the charge-air sensor cover.
  17. Lubricate the pushrods with a light coating of engine oil and install the pushrods, in the as-removed locations.
  18. Install the valve bridges in the as-removed locations.
  19. Install the rocker arm assembly in the as-removed locations. Tighten each rocker arm mounting bolt 30 Nm (22 lbft).
  20. Install the front connector housing assembly.
    1. Install the water pump connector fitting on the water pump.
    2. Install a new gasket on the cylinder head.
    3. Install the front connector housing.
    4. Install the coolant line.
    5. Connect the engine wiring harness to the coolant temperature sensor.
  21. Install the crankshaft turning tool and adjust the valves. Refer to section .
  22. Remove the crankshaft turning tool.
  23. Install the inspection hole end cover on the flywheel housing. Tighten the fasteners 25 Nm (18 lbft).
  24. Install the air cleaner, charge-air inlet, and turbo outlet pipes and hoses.
  25. Install the coolant delivery hoses that connect to the surge tank. See Figure 42213 .
  26. Check that the coolant drain plug is tight and not leaking.
  27. Fill the radiator with coolant.
  28. Install the cylinder head cover. Refer to section .
  29. Install the engine trim panel.

    Note: Bleed the fuel system.

    PERSONAL INJURY

    To avoid injury before starting and running the engine, ensure the vehicle is parked on a level surface, parking brake is set, and the wheels are blocked.

    PERSONAL INJURY

    Diesel engine exhaust and some of its constituents are known to the State of California to cause cancer, birth defects, and other reproductive harm.

    • Always start and operate an engine in a well ventilated area.
    • If operating an engine in an enclosed area, vent the exhaust to the outside.
    • Do not modify or tamper with the exhaust system or emission control system.
  30. Turn on the ignition key switch and run the engine. Observe the oil pressure gauge to verify the correct oil pressure. The minimum oil pressure reading at idle speed is listed in Table . Pay attention to the coolant temperature gauge, warning lights, fluid leaks, and any other signs of a problem.

    Description ‪

    Minimum Oil Pressure Reading ‪

    Engine at Idle Speed ‪

    50 kPa (7 psi) ‪

    Engine at Max. rpm ‪

    250 kPa (36 psi) ‪

    Oil Pressure Readings
  31. Stop the engine, check the coolant level, and top off if necessary.
Cylinder Head Inspection

Inspect the cylinder head as follows: ‪

  1. Measure cylinder-head overall height and variation of parallelism from top-to-bottom contact surfaces. See Figure 42218 . If the measurement is less than the permissible minimum height, replace the cylinder head.

    Measuring the Cylinder Head

  2. Inspect the bottom contact surface of the cylinder head for the permissible difference of flatness in the longitudinal direction. The specifications for cylinder head height and mating surface warpage are listed in Table and in Table .

    Height of Cylinder Head ‪

    6-Cylinder ‪

    4-Cylinder ‪

    When New ‪

    107.9 to 108.1 mm (4.25 to 4.26 in.) ‪

    107.9 to 108.1 mm (4.25 to 4.26 in.) ‪

    After Machining ‪

    106.9 mm (4.21 in.) ‪

    106.9 mm (4.21 in.) ‪

    Cylinder Head Height Specifications

    Maximum Lengthwise Head Mating Surface Warpage ‪

    6-Cylinder ‪

    4-Cylinder ‪

    Over Entire Length ‪

    0.07 mm (0.003 in.) ‪

    0.05 mm (0.002 in.) ‪

    Over a Length of 150 mm (6 in.) ‪

    0.02 mm (0.0008 in.) ‪

    0.02 mm (0.0008 in.) ‪

    Cylinder Head Mating Surface Warpage
Compression Testing

To do compression testing the nozzle holder will need to be removed and the compression tester installed. ‪

  1. Set the parking brake and chock the tires.

    Note: To do this procedure, coolant temperature must be between 70 to 95C (158 and 203F).

    PERSONAL INJURY

    To avoid injury before starting and running the engine, ensure the vehicle is parked on a level surface, parking brake is set, and the wheels are blocked.

    PERSONAL INJURY

    Diesel engine exhaust and some of its constituents are known to the State of California to cause cancer, birth defects, and other reproductive harm.

    • Always start and operate an engine in a well ventilated area.
    • If operating an engine in an enclosed area, vent the exhaust to the outside.
    • Do not modify or tamper with the exhaust system or emission control system.
  2. Turn on the ignition key switch and run the engine until it reaches operating temperature.
  3. Shut down the engine.
  4. Remove the nozzle holder. See Figure 42208 .

    1. Nozzle Holder ‪

    3. Hold-Down Clamp ‪

    2. Bolt ‪

    Removing the Nozzle Holder

  5. Insert the compression test adaptor J-46386 into the cylinder head. See Figure 41869 . Use the hold-down clamp and bolt included in the kit.

    1. Bolt ‪

    3. End Cover (constant throttle) ‪

    2. Hold-Down Clamp ‪

    Installing the Connector

    1. Make sure the smooth surface on the O-ring is pointing toward the test adaptor J-46386 .
    2. Install the hold-down clamp with the two prongs around the test adaptor. Turn the hold-down clamp (at the cylinder head) until the button in the base of the hold-down clamp is aligned with the locating element in the end cover of the constant throttle valve end cover.
    3. Tighten the hold-down clamp bolt 30 Nm (22 lbft) for a hex-head bolt, or 35 Nm (26 lbft) for the 12-point head with the spherical collar.
    4. Note: Follow the equipment manufacturer's operating instructions to connect the compression tester.

  6. Attach the compression tester J-6692B to the test adaptor J-46386 . Thread the fitting at the end of the tester to the top of the test adaptor. See Figure 42209 .

    1. Hold-Down Bolt ‪

    3. End Cover (constant throttle) ‪

    2. Hold-Down Clamp ‪

    4. O-ring ‪

    Testing Compression Pressure

Test as follows: ‪

  1. Remove either of the electrical connectors from the DDEC-ECU control unit. When this is done, the engine will not start.
  2. For each cylinder, use the starter to crank the engine at least 8 engine revolutions. The results will be recorded on the gauge of the tester.
  3. Compare measurements on the gauge with the values listed in Table .

    Description ‪

    Pressure ‪

    Compression Pressure at Starter Speed ‪

    2800 kPa (406 psi) ‪

    Permissible Difference Between Individual Cylinders ‪

    400 kPa (58 psi) ‪

    Compression Testing
  4. If the pressure measured is below the chart compression pressure or above the permissible difference, determine the cause and correct the problem.

Install the nozzle holder as follows: ‪

  1. Connect the DDEC-ECU control unit.
  2. Connect minidiag2 to the vehicle and clear all inactive fault codes.

    Note: Follow the equipment manufacturer's operating instructions.

  3. Disconnect the compression tester from the test adaptor. See Figure 42209 .
  4. Remove the compression test adaptor. See Figure 41869 .
  5. Install the nozzle holder. See Figure 42208 .
  6. Install and adjust the hold-down clamp.
    1. Position the hold-down clamp on the nozzle holder and install the hold-down clamp bolt.
    2. Tighten the hold-down bolt 30 Nm (22 lbft) for a hex-head bolt, or 35 Nm (26 lbft) for the 12-point head with the spherical collar.
  7. Repeat this procedure for each cylinder.
  8. Remove the chocks from the tires.

Oil Separator Removal

Remove oil separator as follows: ‪

  1. Apply the parking brakes, and chock the tires.
  2. Open the hood.
  3. Remove the engine trim panel.
  4. Remove the cylinder head cover.
  5. Remove the oil separator front cover from the cylinder head cover. See Figure 42219 .

    1. Cylinder Head Cover ‪

    5. Oil Separator Front Cover ‪

    2. Wire Filter (Short) ‪

    6. Oil Separator Front Cover Gasket/Diaphragm ‪

    3. Wire Filter (Long) ‪

    7. Spring ‪

    4. Oil Separator Front Cover Screws ‪

    Oil Separator and Components

  6. Remove the oil separator front cover gasket/diaphragm and spring.
  7. Remove both wire filters from inside the cylinder head cover.
Oil Separator Inspection

Inspect and clean the wire filters and the sealing surfaces. Replace, if necessary. ‪

Oil Separator Installation

Install the oil separator as follows: ‪

  1. Install both wire filters into the cylinder head cover. First insert the shorter filter, then the longer one.
  2. Install the spring and the oil separator front cover gasket/diaphragm.
  3. Install the oil separator front cover and bolts. Torque bolts to 25Nm (18 lbft).
  4. Install the cylinder head cover. Refer to section .
  5. Install the engine trim panel.
  6. Close the hood and remove the chocks from the tires.