Mercedes-Benz Cars 2000-05

Cylinder Head 2

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Removal & Installation



3.2L (112) And 4.3L (113) Engines

NOTE
Cylinder head tightening illustrations are located in Section 1 of this manual. The illustrations follow the Torque Charts.

  1. Before servicing the vehicle, refer to the precautions in the beginning of this section.
  2.  
  3. Properly relieve the fuel system pressure and drain the engine coolant. Place a guard plate behind the radiator/condenser to protect it from damage.
  4.  
  5. Remove or disconnect the following:
    NOTE
    The intake manifold system must not be disassembled.



    Negative battery cable
     
    Fan clutch, fan and shroud
     
    Engine cover
     
    Air cleaner housing, resonance pipe and body
     
    Fuel line
     
    Ignition coils
     
    Cylinder head covers
     

  6.  
  7. Remove or disconnect the following:

    Intake manifold
     
    Vacuum switchover valve
     
    Camshaft Position (CMP) sensor
     

  8.  
  9. Lock the autoMatic belt tensioner by rotating the tensioner counterclockwise until a 5mm drift or pin fits through the tensioner, and then remove the serpentine belt.
  10.  
  11. Remove or disconnect the following:

    Power steering pump. Position it aside leaving the hoses attached
     
    Serpentine belt
     
    Heater hose at the firewall
     
    Exhaust system
     

  12.  
  13. Rotate the engine clockwise to position the crankshaft 40 degrees ATDC.
    WARNING
    The engine must not be rotated backwards.

  14.  
  15. Lock the camshafts using camshaft locking tools.
  16.  
  17. Remove or disconnect the following:
    CAUTION
    Never use a prybar between the head and block.



    Generator
     
    Timing chain tensioner
     
    Camshaft gears. Attach to the chain with a cable tie
     
    Camshaft bearing bridges
     
    Camshafts
     
    Timing case-to-cylinder head bolts
     
    Cylinder head bolts in the reverse order of the illustrated sequence
     

  18.  
  19. Remove the cylinder head and clean all gasket material from the sealing surfaces. Be sure the cylinder head locating dowels are positioned in the engine block.
  20.  
  21. Inspect length of the cylinder head bolt shaft. New bolt length is 141.5mm and the maximum permissible length is 144.5mm. Replace bolts that measure greater than the maximum permissible length.

    Click image to see an enlarged view

    Fig. Exploded view of the cylinder head accessory components-3.2L (112) engine shown



    Click image to see an enlarged view

    Fig. Exploded view of the cylinder head removal-3.2L (112) engine shown

  22.  

To install:

  1. Clean the head bolt threads and apply clean engine oil to the thread and head contact surfaces.
  2.  
  3. Install the cylinder head gasket and head. Torque the head bolts according to the illustrated sequence as follows:

    Step 1: 15 ft. lbs. (20 Nm)
     
    Step 2: 37 ft. lbs. (50 Nm)
     
    Step 3: 60-70 degrees
     
    Step 4: Additional 60-70 degrees
     

  4.  
  5. Install or connect the following:

    Timing case-to-cylinder head bolts. Torque to 15 ft. lbs. (20 Nm)
     
    Camshafts
     
    Camshaft bearing bridges
     
    Camshaft gear. Torque the mounting bolt to 37 ft. lbs. (50 Nm) plus an additional 90 degrees
     
    Timing chain tensioner with new gasket. Torque to 59 ft. lbs. (80 Nm)
     
    Generator
     

  6.  
  7. Remove the camshaft locking plates.
  8.  
  9. Install or connect the following:

    Exhaust system. Torque mounting nuts to 15 ft. lbs. (20 Nm)
     
    Heater hose
     
    Power steering pump
     
    Serpentine belt
     
    CMP sensor
     
    Vacuum switchover valve
     
    Intake manifold
     
    Cylinder head covers. Torque the bolts to 88 inch lbs. (10 Nm)
     
    Ignition coils. Torque the mounting bolts to 70 inch lbs. (8 Nm)
     
    Fuel line
     
    Air cleaner housing, resonance pipe and body
     
    Engine cover
     
    Fan clutch, fan and shroud
     

  10.  
  11. Remove the guard plate from the radiator/condenser.
  12.  
  13. Fill the cooling system, connect the negative battery cable, start the engine and check for leaks.
  14.  


NOTE
Cylinder head tightening illustrations are located in Section 1 of this manual. The illustrations follow the Torque Charts.

  1. Before servicing the vehicle, refer to the Precautions section.
  2.  
  3. Properly relieve the fuel system pressure and drain the engine coolant. Place a guard plate behind the radiator/condenser to protect it from damage.
  4.  
  5. Remove or disconnect the following:
    NOTE
    The intake manifold system must not be disassembled.



    Negative battery cable
     
    Fan clutch, fan and shroud
     
    Engine cover
     
    Air cleaner housing, resonance pipe and body
     
    Fuel line
     
    Ignition coils
     
    Cylinder head covers
     

  6.  
  7. Remove or disconnect the following:

    Intake manifold
     
    Vacuum switchover valve
     
    Camshaft Position (CMP) sensor
     

  8.  
  9. Lock the autoMatic belt tensioner by rotating the tensioner counterclockwise until a 5mm drift or pin fits through the tensioner, and then remove the serpentine belt.
  10.  
  11. Remove or disconnect the following:

    Power steering pump. Position it aside leaving the hoses attached
     
    Serpentine belt
     
    Heater hose at the firewall
     
    Exhaust system
     

  12.  
  13. Rotate the engine clockwise to position the crankshaft 40 degrees ATDC.
    WARNING
    The engine must not be rotated backwards.

  14.  
  15. Lock the camshafts using camshaft locking tools.
  16.  
  17. Remove or disconnect the following:
    CAUTION
    Never use a prybar between the head and block.



    Generator
     
    Timing chain tensioner
     
    Camshaft gears. Attach to the chain with a cable tie
     
    Camshaft bearing bridges
     
    Camshafts
     
    Timing case-to-cylinder head bolts
     
    Cylinder head bolts in the reverse order of the illustrated sequence
     

  18.  
  19. Remove the cylinder head and clean all gasket material from the sealing surfaces. Be sure the cylinder head locating dowels are positioned in the engine block.
  20.  
  21. Inspect length of the cylinder head bolt shaft. New bolt length is 141.5mm and the maximum permissible length is 144.5mm. Replace bolts that measure greater than the maximum permissible length.

    Click image to see an enlarged view

    Fig. Exploded view of the cylinder head accessory components-3.2L (112) engine shown



    Click image to see an enlarged view

    Fig. Exploded view of the cylinder head removal-3.2L (112) engine shown

  22.  

To install:

  1. Clean the head bolt threads and apply clean engine oil to the thread and head contact surfaces.
  2.  
  3. Install the cylinder head gasket and head. Torque the head bolts according to the illustrated sequence as follows:

    Step 1: 15 ft. lbs. (20 Nm)
     
    Step 2: 37 ft. lbs. (50 Nm)
     
    Step 3: 60-70 degrees
     
    Step 4: Additional 60-70 degrees
     

  4.  
  5. Install or connect the following:

    Timing case-to-cylinder head bolts. Torque to 15 ft. lbs. (20 Nm)
     
    Camshafts
     
    Camshaft bearing bridges
     
    Camshaft gear. Torque the mounting bolt to 37 ft. lbs. (50 Nm) plus an additional 90 degrees
     
    Timing chain tensioner with new gasket. Torque to 59 ft. lbs. (80 Nm)
     
    Generator
     

  6.  
  7. Remove the camshaft locking plates.
  8.  
  9. Install or connect the following:

    Exhaust system. Torque mounting nuts to 15 ft. lbs. (20 Nm)
     
    Heater hose
     
    Power steering pump
     
    Serpentine belt
     
    CMP sensor
     
    Vacuum switchover valve
     
    Intake manifold
     
    Cylinder head covers. Torque the bolts to 88 inch lbs. (10 Nm)
     
    Ignition coils. Torque the mounting bolts to 70 inch lbs. (8 Nm)
     
    Fuel line
     
    Air cleaner housing, resonance pipe and body
     
    Engine cover
     
    Fan clutch, fan and shroud
     

  10.  
  11. Remove the guard plate from the radiator/condenser.
  12.  
  13. Fill the cooling system, connect the negative battery cable, start the engine and check for leaks.
  14.  

4.2L And 5.0L (119) Engines
  1. Before servicing the vehicle, refer to the Precautions section.
  2.  
  3. Drain the engine coolant.
  4.  
  5. Remove or disconnect the following:

    Negative battery cable
     
    Engine cover
     
    Front covers
     

  6.  
  7. Crank the No. 1 piston of the engine to 45 degrees Before Top Dead Center (BTDC). Look for the4/5
  8.  
  9. Mark all 4 camshaft timing gears and timing chain with colored dots at about 11 o'clock for the right outer and left inner camshaft sprocket and 1 o'clock for the right inner and left outer camshaft sprocket.
  10.  
  11. Remove or disconnect the following:

    Timing chain tensioner and top guide rails
     
    Camshaft gears and adjusters
     
    Electrical wiring, hoses and cables
     
    Intake manifold
     
    Dipstick guide tube
     
    Exhaust pipes and manifolds
     
    Cylinder head covers
     

  12.  

Be sure the engine is cold before removing cylinder head bolts. On the "close-deck" crankcase, the cylinder head bolts have different lengths.

  1. Loosen the cylinder head bolts in the reverse order of the illustrated tightening sequence.
  2.  
  3. Remove the cylinder head and clean all gasket material from the sealing surfaces. Be sure the cylinder head locating dowels are positioned in the engine block.
  4.  
  5. Inspect length of the cylinder head bolts. New bolt length is 160mm and the maximum permissible length is 163.5mm. Replace bolts that measure greater than the maximum permissible length.
  6.  

To install:



Click image to see an enlarged view

Fig. Cylinder head bolt tightening sequence-4.2L and 5.0L (119) Engines


NOTE
The head gasket is not watertight until the engine has reached operating temperature. Do not pressure test the cooling system until the engine has reached operating temperature.

  1. Clean the head bolt threads, and then apply clean engine oil to the thread and head contact surfaces.
  2.  
  3. Install the cylinder head gasket and head. Torque the bolts in sequence, as follows:
    1. Step 1: 41 ft. lbs. (55 Nm) .
    2.  
    3. Step 2: + 90 degrees .
    4.  
    5. Step 3: + additional 90 degrees .
    6.  

  4.  
  5. Torque the M8 bolts near the timing sprockets to 18 ft. lbs. (25 Nm).
  6.  


NOTE
Bolts that are screwed into the front of the cylinder head must be coated with sealant when installed.

  1. Install or connect the following:

    Cylinder head covers
     
    Exhaust pipes and manifolds
     
    Dipstick guide tube
     
    Intake manifold
     
    Wiring, hoses and cables
     
    Camshaft gears and adjusters
     
    Timing chain tensioner and top guide rails
     
    Front covers
     
    Engine cover
     
    Coolant
     
    Engine oil
     
    Negative battery cable
     

  2.  


NOTE
Cylinder head tightening illustrations are located in Section 1 of this manual. The illustrations follow the Torque Charts.

  1. Before servicing the vehicle, refer to the precautions in the beginning of this section.
  2.  
  3. Drain the engine coolant.
  4.  
  5. Remove or disconnect the following:

    Negative battery cable
     
    Engine cover
     
    Front covers
     

  6.  
  7. Crank the No. 1 piston of the engine to 45 degrees BTDC. Look for the 4/5 on the timing indicator.
  8.  
  9. Mark all 4 camshaft timing gears and timing chain with colored dots at about 11 o'clock for the right outer and left inner camshaft sprocket and 1 o'clock for the right inner and left outer camshaft sprocket.
  10.  
  11. Remove or disconnect the following:
    NOTE
    Be sure the engine is cold before removing cylinder head bolts. On the "close-deck" crankcase, the cylinder head bolts have different lengths.



    Timing chain tensioner and top guide rails
     
    Camshaft gears and adjusters
     
    Electrical wiring, hoses and cables
     
    Intake manifold
     
    Dipstick guide tube
     
    Exhaust pipes and manifolds
     
    Cylinder head covers
     

  12.  
  13. Loosen the cylinder head bolts in the reverse order of the illustrated tightening sequence.
  14.  
  15. Remove the cylinder head and clean all gasket material from the sealing surfaces. Be sure the cylinder head locating dowels are positioned in the engine block.
  16.  
  17. Inspect length of the cylinder head bolts. New bolt length is 160mm and the maximum permissible length is 163.5mm. Replace bolts that measure greater than the maximum permissible length.
  18.  

To install:


NOTE
The head gasket is not watertight until the engine has reached operating temperature. Do not pressure test the cooling system until the engine has reached operating temperature.

  1. Clean the head bolt threads, and then apply clean engine oil to the thread and head contact surfaces.
  2.  
  3. Install the cylinder head gasket and head. Torque the bolts in sequence, as follows:
    NOTE
    Bolts that are screwed into the front of the cylinder head must be coated with sealant when installed.



    41 ft. lbs. (55 Nm)
     
    + 90 degrees
     
    + additional 90 degrees
     
    Torque the M8 bolts near the timing sprockets to 18 ft. lbs. (25 Nm)
     

  4.  
  5. Install or connect the following:

    Cylinder head covers
     
    Exhaust pipes and manifolds
     
    Dipstick guide tube
     
    Intake manifold
     
    Wiring, hoses and cables
     
    Camshaft gears and adjusters
     
    Timing chain tensioner and top guide rails
     
    Front covers
     
    Engine cover
     
    Coolant
     
    Engine oil
     
    Negative battery cable
     

  6.  


NOTE
Cylinder head tightening illustrations are located in Section 1 of this manual. The illustrations follow the Torque Charts.

  1. Before servicing the vehicle, refer to the Precautions section.
  2.  
  3. Drain the engine coolant.
  4.  
  5. Remove or disconnect the following:

    Negative battery cable
     
    Engine cover
     
    Front covers
     

  6.  
  7. Crank the No. 1 piston of the engine to 45 degrees BTDC. Look for the 4/5 on the timing indicator.
  8.  
  9. Mark all 4 camshaft timing gears and timing chain with colored dots at about 11 o'clock for the right outer and left inner camshaft sprocket and 1 o'clock for the right inner and left outer camshaft sprocket.
  10.  
  11. Remove or disconnect the following:
    NOTE
    Be sure the engine is cold before removing cylinder head bolts. On the "close-deck" crankcase, the cylinder head bolts have different lengths.



    Timing chain tensioner and top guide rails
     
    Camshaft gears and adjusters
     
    Electrical wiring, hoses and cables
     
    Intake manifold
     
    Dipstick guide tube
     
    Exhaust pipes and manifolds
     
    Cylinder head covers
     

  12.  
  13. Loosen the cylinder head bolts in the reverse order of the illustrated tightening sequence.
  14.  
  15. Remove the cylinder head and clean all gasket material from the sealing surfaces. Be sure the cylinder head locating dowels are positioned in the engine block.
  16.  
  17. Inspect length of the cylinder head bolts. New bolt length is 160mm and the maximum permissible length is 163.5mm. Replace bolts that measure greater than the maximum permissible length.
  18.  

To install:


NOTE
The head gasket is not watertight until the engine has reached operating temperature. Do not pressure test the cooling system until the engine has reached operating temperature.

  1. Clean the head bolt threads, and then apply clean engine oil to the thread and head contact surfaces.
  2.  
  3. Install the cylinder head gasket and head. Torque the bolts in sequence, as follows:
    NOTE
    Bolts that are screwed into the front of the cylinder head must be coated with sealant when installed.



    41 ft. lbs. (55 Nm)
     
    + 90 degrees
     
    + additional 90 degrees
     
    Torque the M8 bolts near the timing sprockets to 18 ft. lbs. (25 Nm)
     

  4.  
  5. Install or connect the following:

    Cylinder head covers
     
    Exhaust pipes and manifolds
     
    Dipstick guide tube
     
    Intake manifold
     
    Wiring, hoses and cables
     
    Camshaft gears and adjusters
     
    Timing chain tensioner and top guide rails
     
    Front covers
     
    Engine cover
     
    Coolant
     
    Engine oil
     
    Negative battery cable
     

  6.  

6.0L (120) Engines

NOTE
Cylinder head tightening illustrations are located in Section 1 of this manual. The illustrations follow the Torque Charts.

  1. Before servicing the vehicle, refer to the Precautions section.
  2.  
  3. Drain the cooling system.
  4.  
  5. Remove or disconnect the following:

    Negative battery cable
     
    Intake manifold
     
    Engine assembly, on S models
     
    Exhaust pipes and bracket, on SL models
     
    Valve covers
     

  6.  
  7. Rotate the crankshaft to 30 degrees After Top Dead Center (ATDC).
  8.  
  9. Matchmark the camshaft sprockets to the timing chain as illustrated.
  10.  
  11. Remove or disconnect the following:

    Timing chain tensioner
     
    Timing chain from camshaft sprockets
     
    Left head ventilation tube
     
    Transmission dipstick tube
     
    Oil dipstick tube
     
    Timing chain guide rails
     
    Secondary air injection lines
     
    Exhaust manifold, on S models
     
    Coolant hose at the rear of the head
     

  12.  
  13. Loosen the head bolts in stages, in the reverse of the tightening sequence. Remove the cylinder heads with the exhaust manifolds attached. Clean all gasket material from the sealing surfaces. Be sure the cylinder head locating dowels are positioned in the engine block.
  14.  
  15. Measure the cylinder head bolts. New bolts are 168mm long, and the maximum allowable length is 171mm. Replace any bolts that exceed the maximum length.
  16.  


    Click image to see an enlarged view

    Fig. Matchmark the timing chain and sprockets for installation-6.0L (120) engines


To install:



Click image to see an enlarged view

Fig. Cylinder head bolt tightening sequence-6.0L (120) Engine


NOTE
The head gasket is not watertight until the engine has reached operating temperature. Do not pressure test the cooling system until the engine has reached operating temperature.

  1. Install the cylinder head gasket and head. Torque the bolts in sequence, as follows:
    1. Step 1: 41 ft. lbs. (55Nm).
    2.  
    3. Step 2: + 90 degrees.
    4.  
    5. Step 3: + another 90 degrees.
    6.  

  2.  
  3. Install or connect the following:

    Coolant hose
     
    Exhaust manifold, on S models
     
    Secondary air injection lines
     
    Timing chain guide rails
     
    Oil dipstick tube
     
    Transmission dipstick tube
     
    Ventilation tube
     

  4.  
  5. Align the matchmarks and install the timing chain.

    Timing chain tensioner. Verify the correct valve timing.
     
    Valve covers
     
    Engine assembly, on S models
     
    Exhaust pipes to the manifolds and connect the exhaust pipe bracket to the transmission, on SL models
     
    Intake manifold
     
    Engine oil
     
    Coolant
     
    Negative battery cable
     

  6.  


NOTE
Cylinder head tightening illustrations are located in Section 1 of this manual. The illustrations follow the Torque Charts.

  1. Before servicing the vehicle, refer to the precautions in the beginning of this section.
  2.  
  3. Drain the cooling system.
  4.  
  5. Remove or disconnect the following:

    Negative battery cable
     
    Intake manifold
     
    Engine assembly on S models
     
    Exhaust pipes and bracket on SL models
     
    Valve covers
     

  6.  
  7. Rotate the crankshaft to 30 degrees ATDC.
  8.  
  9. Matchmark the camshaft sprockets to the timing chain as illustrated.

    Click image to see an enlarged view

    Fig. Matchmark the timing chain and sprockets for installation-6.0L (120) engines

  10.  
  11. Remove or disconnect the following:

    Timing chain tensioner
     
    Timing chain from camshaft sprockets
     
    Left head ventilation tube
     
    Transmission dipstick tube
     
    Oil dipstick tube
     
    Timing chain guide rails
     
    Secondary air injection lines
     
    Exhaust manifold on S models
     
    Coolant hose at the rear of the head
     

  12.  
  13. Loosen the head bolts in stages, in the reverse of the tightening sequence. Remove the cylinder heads with the exhaust manifolds attached. Clean all gasket material from the sealing surfaces. Be sure the cylinder head locating dowels are positioned in the engine block.
  14.  
  15. Measure the cylinder head bolts. New bolts are 168mm long, and the maximum allowable length is 171mm. Replace any bolts that exceed the maximum length.
  16.  

To install:


NOTE
The head gasket is not watertight until the engine has reached operating temperature. Do not pressure test the cooling system until the engine has reached operating temperature.

  1. Install the cylinder head gasket and head. Torque the bolts in sequence, as follows:

    41 ft. lbs. (55Nm).
     
    + 90 degrees.
     
    + another 90 degrees.
     

  2.  
  3. Install or connect the following:

    Coolant hose
     
    Exhaust manifold on S models
     
    Secondary air injection lines
     
    Timing chain guide rails
     
    Oil dipstick tube
     
    Transmission dipstick tube
     
    Ventilation tube
     

  4.  
  5. Align the matchmarks and install the timing chain.
  6.  
  7. Install or connect the following:

    Timing chain tensioner. Verify the correct valve timing
     
    Valve covers
     
    Engine assembly on S models
     
    For SL models, connect the exhaust pipes to the manifolds and connect the exhaust pipe bracket to the transmission
     
    Intake manifold
     
    Engine oil
     
    Coolant
     
    Negative battery cable
     

  8.  


NOTE
Cylinder head tightening illustrations are located in Section 1 of this manual. The illustrations follow the Torque Charts.

  1. Before servicing the vehicle, refer to the Precautions section.
  2.  
  3. Drain the cooling system.
  4.  
  5. Remove or disconnect the following:

    Negative battery cable
     
    Intake manifold
     
    Engine assembly on S models
     
    Exhaust pipes and bracket on SL models
     
    Valve covers
     

  6.  
  7. Rotate the crankshaft to 30 degrees ATDC.
  8.  
  9. Matchmark the camshaft sprockets to the timing chain as illustrated.

    Click image to see an enlarged view

    Fig. Matchmark the timing chain and sprockets for installation-6.0L (120) engines

  10.  
  11. Remove or disconnect the following:

    Timing chain tensioner
     
    Timing chain from camshaft sprockets
     
    Left head ventilation tube
     
    Transmission dipstick tube
     
    Oil dipstick tube
     
    Timing chain guide rails
     
    Secondary air injection lines
     
    Exhaust manifold on S models
     
    Coolant hose at the rear of the head
     

  12.  
  13. Loosen the head bolts in stages, in the reverse of the tightening sequence. Remove the cylinder heads with the exhaust manifolds attached. Clean all gasket material from the sealing surfaces. Be sure the cylinder head locating dowels are positioned in the engine block.
  14.  
  15. Measure the cylinder head bolts. New bolts are 168mm long, and the maximum allowable length is 171mm. Replace any bolts that exceed the maximum length.
  16.  

To install:


NOTE
The head gasket is not watertight until the engine has reached operating temperature. Do not pressure test the cooling system until the engine has reached operating temperature.

  1. Install the cylinder head gasket and head. Torque the bolts in sequence, as follows:

    41 ft. lbs. (55Nm).
     
    + 90 degrees.
     
    + another 90 degrees.
     

  2.  
  3. Install or connect the following:

    Coolant hose
     
    Exhaust manifold on S models
     
    Secondary air injection lines
     
    Timing chain guide rails
     
    Oil dipstick tube
     
    Transmission dipstick tube
     
    Ventilation tube
     

  4.  
  5. Align the matchmarks and install the timing chain.
  6.  
  7. Install or connect the following:

    Timing chain tensioner. Verify the correct valve timing
     
    Valve covers
     
    Engine assembly on S models
     
    For SL models, connect the exhaust pipes to the manifolds and connect the exhaust pipe bracket to the transmission
     
    Intake manifold
     
    Engine oil
     
    Coolant
     
    Negative battery cable
     

  8.  

Diesel Engine

NOTE
Use care to ensure that the valve timing is not disturbed.

  1. Before servicing the vehicle, refer to the Precautions section.
  2.  
  3. Drain the engine coolant.
  4.  
  5. Remove or disconnect the following:

    Negative battery cable
     
    Hoses and wires
     
    Camshaft cover
     
    Throttle linkage
     
    Camshaft sprocket nuts
     

  6.  
  7. Mark the chain, sprocket and cam for ease of assembly. Remove the sprocket and chain and wire it aside. Unbolt the manifolds and exhaust header pipe and set them aside.
    NOTE
    Be sure the chain is securely wired so it will not slide into the engine.

  8.  
  9. Remove or disconnect the following:

    Cylinder head bolts in the reverse order of the illustrated sequence.
     
    Cylinder head
     

  10.  
  11. Clean all gasket material from the sealing surfaces. Be sure the cylinder head locating dowels are positioned in the engine block.
    WARNING
    All Diesel engines utilize cylinder head stretch bolts. These bolts undergo a permanent stretch each time they are tightened. When a maximum length is reached, they must be replaced with new bolts. Before tightening the head bolts on these engines, refer to the illustration for the specific length of the bolts.



    Click image to see an enlarged view

    Fig. Be sure to replace bolts that are beyond maximum length-Diesel engines

  12.  

To install:

  1. Install the cylinder head and gasket. Torque the cylinder head bolts in sequence as follows:

    11 ft. lbs. (15 Nm)
     
    20 ft. lbs. (35 Nm)
     
    + 90 degrees
     
    wait 10 minutes
     
    + additional 90 degrees
     

  2.  
  3. Install or connect the following:

    Manifolds and exhaust header pipe. Torque the pipe fasteners to 24 ft. lbs. (34 Nm)
     
    Sprocket and chain
     
    Camshaft sprocket nuts
     
    Trowel linkage
     
    Camshaft cover
     
    Hoses and wires
     
    Coolant
     
    Negative battery cable
     

  4.  

M111 And M271 Engines
  1. Before servicing the vehicle, refer to the Precautions section.
  2.  
  3. Drain the engine coolant.
  4.  
  5. Remove or disconnect the following:

    Negative battery cable
     
    Exhaust system and bracket at transmission
     
    Thermostat housing cover
     
    Air intake tubes
     
    Electrical connectors
     
    Coolant hose (3) at the rear of the cylinder head
     
    Intake manifold (19). Position it aside.
     
    Crankcase breather hose
     
    Manifold bracket (2)
     
    Valve cover
     
    Thermostat housing
     
    Cylinder head front cover
     
    Heated (HO 2 S) sensor connector
     
    Engine and transmission dipstick guide tubes (7) (8)
     

  6.  
  7. On M111 engines, position crankshaft to 20-30 degrees After Top Dead Center (ATDC) for cylinder No. 1. Lock the camshafts (75 and 78) with locking pins (01) and matchmark the timing chain to the sprockets.
  8.  
  9. On M271 engines, position the engine at Top Dead Center (TDC) and check that the marks on the camshaft sprockets align with the marks on the bearing caps.
  10.  
  11. Remove or disconnect the following:

    Chain tensioner (14)
     
    Chain guide rail in the cylinder head
     
    On M111 engines, the exhaust camshaft sprocket (76) and intake camshaft sprocket (74)
     
    On M271 engines, the intake and exhaust camshafts.
     

  12.  
  13. Install the cylinder head removal bracket (16) and remove the guide rail pin (11), using a threaded extractor.
    CAUTION
    Never use a prybar between the head and block.



    Timing chain housing bolts (A)
     
    Cylinder head bolts in the reverse order of the illustrated tightening sequence
     

  14.  
  15. Remove the cylinder head and clean all gasket material from the sealing surfaces. Be sure the cylinder head locating dowels are positioned correctly in the engine block.
  16.  
  17. Inspect length of the cylinder head bolt shaft. New bolt length is 102mm and the maximum permissible length is 105mm. Replace bolts that measure greater than the maximum permissible length.
  18.  

To install:

Click image to see an enlarged view

Fig. Exploded view of the cylinder head accessory components-M111 engine



Click image to see an enlarged view

Fig. Exploded view of the cylinder head mounting-M111 engine



Click image to see an enlarged view

Fig. Cylinder head bolt tightening sequence-M111 engine



Click image to see an enlarged view

Fig. Cylinder head bolt tightening sequence-M271 engine


NOTE
The head gasket is not watertight until the engine has reached operating temperature. Do not pressure test the cooling system until the engine has reached operating temperature.

  1. Verify the Top Dead Center (TDC) position of the No. 1 cylinder. Clean the head bolt threads and apply clean engine oil to the thread and head contact surfaces.
  2.  
  3. Install or connect the following:

    Head gasket and cylinder head. On M111 engines, torque the head bolts using the illustrated sequence to 41 ft. lbs. (55 Nm) plus 90 degrees, then an additional 90 degrees. On M271 engines, torque the head bolts using the illustrated sequence to 33 ft. lbs. (45 Nm) plus 90 degrees, then an additional 90 degrees.
     
    Timing chain housing bolts
     
    Guide rail pin
     

  4.  
  5. Remove the cylinder head removal bracket.

    Intake and exhaust camshaft sprockets or camshafts as appicable
     
    Guide rail
     
    Chain tensioner
     

  6.  
  7. Remove the camshaft locking pins and verify timing mark alignment.

    Engine oil and transmission dipstick guide tubes
     
    HO 2 S sensor
     
    Cylinder head front cover
     
    Thermostat housing
     
    Valve cover
     
    Cylinder head coolant hose
     
    Crankcase breather hose
     
    Intake manifold
     
    Electrical connectors
     
    Thermostat housing cover and air intake tubes
     
    Exhaust system and bracket
     
    Coolant
     
    Negative battery cable
     

  8.  

M112 And M113 Engines
  1. Before servicing the vehicle, refer to the Precautions section.
  2.  
  3. Properly relieve the fuel system pressure and drain the engine coolant. Place a guard plate behind the radiator/condenser to protect it from damage.
  4.  
  5. Remove or disconnect the following:
    NOTE
    The intake manifold system must not be disassembled.



    Negative battery cable
     
    Fan clutch, fan and shroud
     
    Engine cover
     
    Air cleaner housing, resonance pipe and body
     
    Fuel line
     
    Ignition coils
     
    Cylinder head covers
     



    Intake manifold
     
    Vacuum switchover valve
     
    Camshaft Position (CMP) sensor
     

  6.  
  7. Lock the Automatic belt tensioner by rotating the tensioner counterclockwise until a 5mm drift or pin fits through the tensioner, and then remove the serpentine belt.
  8.  
  9. Remove or disconnect the following:

    Power steering pump and position it aside leaving the hoses attached
     
    Serpentine belt
     
    Heater hose at the firewall
     
    Exhaust system
     

  10.  
  11. Rotate the engine clockwise to position the crankshaft 40 degrees After Top Dead Center (ATDC).
    WARNING
    The engine must not be rotated backwards.

  12.  
  13. Lock the camshafts using camshaft locking tools.
  14.  
  15. Remove or disconnect the following:
    CAUTION
    Never use a prybar between the head and block.



    Generator
     
    Timing chain tensioner
     
    Camshaft gears. Attach to the chain with a cable tie.
     
    Camshaft bearing bridges
     
    Camshafts
     
    Timing case-to-cylinder head bolts
     
    Cylinder head bolts in the reverse order of the illustrated tightening sequence
     

  16.  
  17. Remove the cylinder head and clean all gasket material from the sealing surfaces. Be sure the cylinder head locating dowels are positioned in the engine block.
  18.  
  19. Inspect length of the cylinder head bolt shaft. New bolt length is 141.5mm and the maximum permissible length is 144.5mm. Replace bolts that measure greater than the maximum permissible length.

    Click image to see an enlarged view

    Fig. Exploded view of the cylinder head accessory components-M112 shown, M113 engines similar



    Click image to see an enlarged view

    Fig. Exploded view of the cylinder head removal-M112 shown, M113 engines similar



    Click image to see an enlarged view

    Fig. Cylinder head bolt tightening sequence-M112 engine



    Click image to see an enlarged view

    Fig. Cylinder head bolt tightening sequence-M113 engine

  20.  

To install:

  1. Clean the head bolt threads and apply clean engine oil to the thread and head contact surfaces.
  2.  
  3. Install the cylinder head gasket and head. Torque the head bolts according to the illustrated sequence as follows:
    1. Step 1: 7 ft. lbs. (10 Nm).
    2.  
    3. Step 2: 22 ft. lbs. (30 Nm).
    4.  
    5. Step 3: 90 degrees.
    6.  
    7. Step 4: Additional 90 degrees.
    8.  

  4.  
  5. Install or connect the following:

    Timing case-to-cylinder head bolts and torque to 15 ft. lbs. (20 Nm)
     
    Camshafts
     
    Camshaft bearing bridges
     
    Camshaft gear. Torque the mounting bolt to 37 ft. lbs. (50 Nm) plus an additional 90 degrees.
     
    Timing chain tensioner with new gasket. Torque to 59 ft. lbs. (80 Nm).
     
    Generator
     

  6.  
  7. Remove the camshaft locking plates.

    Exhaust system. Torque mounting nuts to 15 ft. lbs. (20 Nm).
     
    Heater hose
     
    Power steering pump
     
    Serpentine belt
     
    CMP sensor
     
    Vacuum switchover valve
     
    Intake manifold
     
    Cylinder head covers.
     
    Ignition coils.
     
    Fuel line
     
    Air cleaner housing, resonance pipe and body
     
    Engine cover
     
    Fan clutch, fan and shroud
     

  8.  
  9. Remove the guard plate from the radiator/condenser.
  10.  
  11. Fill the cooling system, connect the negative battery cable, start the engine and check for leaks.
  12.  

M272 Engines
  1. Before servicing the vehicle, refer to the Precautions section.
  2.  
  3. Properly relieve the fuel system pressure and drain the engine coolant. Place a guard plate behind the radiator/condenser to protect it from damage after removing the engine fan.
  4.  
  5. Remove or disconnect the following:

    Negative battery cable
     
    Engine fan and shroud
     
    Engine cover
     
    Air cleaner housing, resonance pipe and body
     
    Exhaust pipes from exhaust manifolds
     
    Fuel line
     
    Cylinder head covers
     
    Intake manifold
     
    Alternator
     
    Upper guide pulley
     
    Oil filter housing
     
    Power steering reservoir
     

  6.  
  7. Rotate the engine clockwise to position the crankshaft 40 degrees After Top Dead Center (ATDC).
    WARNING
    The engine must not be rotated backwards.

  8.  
  9. Remove or disconnect the following:
    CAUTION
    Never use a prybar between the head and block.


    NOTE
    The rear left bolt on the right cylinder head cannot be removed until the head is removed from the engine. Pull the bolt up slightly and use a cable tie to keep it from sliding back down.



    Timing chain tensioner
     
    Camshaft adjusters
     
    Guide rail pin on the right cylinder head
     
    Air pump and aspirator valve
     
    Cooling hose from the cylinder head
     
    Coolant temperature sensor connector
     
    Oil dipstick guide tube bolt
     
    Guide bolts for slide rail on the left cylinder head
     
    Cylinder head bolts in the reverse order of the illustrated tightening sequence
     

  10.  
  11. Remove the cylinder head and clean all gasket material from the sealing surfaces.
  12.  
  13. Installation is the reverse of removal. Use a new cylinder head gasket and bolts. Torque the head bolts according to the illustrated sequence as follows:
    1. Step 1: Bolts 1-8 to 15 ft. lbs. (20 Nm)
    2.  
    3. Step 2: Bolts 1-8 to 30 ft. lbs. (40 Nm)
    4.  
    5. Step 3: Bolts 1-8 to 30 ft. lbs. (40 Nm) again
    6.  
    7. Step 4: Bolts 1-8, 90 degrees
    8.  
    9. Step 5 Bolts 1-8, an additional 90 degrees
    10.  
    11. Step 6: Bolts 9, to 11 ft. lbs. (15 Nm)
    12.  
    13. Step 7: Bolts 9, 90 degrees

      Click image to see an enlarged view

      Fig. Cylinder head bolt tightening sequence-M272 engine

    14.  

  14.  

 
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