Mercedes-Benz Cars 2000-05

Timing Chain & Sprockets

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Removal & Installation



M111 And M271 Engines

NOTE
An endless timing chain is used on production engines, but a split chain with a connecting link is used for service. The endless chain can be separated with a "chain breaker". Only 1 master link (connecting link) should be used on a chain.

  1. Before servicing the vehicle, refer to the Precautions section.
  2.  
  3. Remove or disconnect the following:

    Negative battery cable
     
    Spark plugs
     
    Valve cover(s)
     
    Engine timing covers
     

  4.  
  5. Clamp the chain to the camshaft gear and cover the opening of the timing chain case.
  6.  
  7. Separate the chain with a chain breaker.
  8.  

To install:

Click image to see an enlarged view

Fig. Replacing the timing chain

  1. Attach a new timing chain (5) to the old chain (4) with a master link (6), center plate (7) and end plate (8). Using a socket wrench on the crankshaft, slowly rotate the engine in the direction of normal rotation. Simultaneously, pull the old chain through until the master link is uppermost on the camshaft sprocket (9). Be sure to keep tension on the chain throughout this procedure.
  2.  
  3. Disconnect the old timing chain and connect the ends of the new chain with the master link. Insert the new connecting link from the rear so the lockwashers can be seen from the front.
  4.  
  5. Rotate the engine until the timing marks align. Check the valve timing.
  6.  
  7. Install or connect the following:

    Engine timing covers
     
    Valve covers
     
    Spark plugs
     
    Negative battery cable
     

  8.  
  9. Start the engine and check operation.
  10.  

M112 And M113 Engines
  1. Before servicing the vehicle, refer to the Precautions section.
  2.  
  3. Disconnect the negative battery cable.
  4.  
  5. Drain the cooling system and engine oil.
  6.  
  7. Remove or disconnect the following:
    WARNING
    The engine must not be rotated backward.



    Timing chain cover
     

  8.  
  9. Rotate the crankshaft clockwise to align the crankshaft timing marks at 40° After Top Dead Center (ATDC). Insure that the grooves in the camshafts (6 in the illustration) align with the cylinder head cover mating surface on the intake side of the cylinder heads.

    Click image to see an enlarged view

    Fig. Camshaft timing marks

  10.  
  11. Lock the camshafts using the Camshaft Locking tools 112 589 00 32 00 and 112 589 01 32 00.

    Camshaft sprockets bolts
     
    Timing chain
     

  12.  

To install:

  1. Align the copper plated links of the timing chain with the marks on the camshaft sprockets, the crankshaft sprocket, and the balancer sprocket for the M112 engines. The M113 engines use an idler sprocket in place of the balance shaft.
  2.  
  3. Install or connect the following:

    Camshaft sprockets along with the timing chain. Tighten the attaching bolts to 37 ft. lbs. (50 Nm) plus 90-100 degrees.
     
    Timing chain cover.
     

  4.  
  5. Fill the cooling system and the crankcase to the correct levels.

    Engine cover
     
    Negative battery cable
     

  6.  
  7. Read fault memory, encode the radio and normalize the power windows.
  8.  

M272 Engines

NOTE
An endless timing chain is used on production engines, but a split chain with a connecting link is used for service. The endless chain can be separated with a "chain breaker". Only 1 master link (connecting link) should be used on a chain.

  1. Before servicing the vehicle, refer to the Precautions section.
  2.  
  3. Remove or disconnect the following:

    Negative battery cable
     
    Spark plugs
     
    Camshafts on the right cylinder head
     

  4.  
  5. Clamp the chain to the camshaft gear and cover the opening of the timing chain case.
  6.  
  7. Separate the chain with a chain breaker.
  8.  

To install:

  1. Attach a new timing chain to the old chain with a master link, center plate and end plate. Using a socket wrench on the crankshaft, slowly rotate the engine in the direction of normal rotation. Simultaneously, pull the old chain through until the master link is uppermost on the camshaft sprocket. Be sure to keep tension on the chain throughout this procedure.
  2.  
  3. Disconnect the old timing chain and connect the ends of the new chain with the master link. Insert the new connecting link from the rear so the lockwashers can be seen from the front.
  4.  
  5. Rotate the engine in the direction of rotation until the timing marks align at 55 degrees Before Top Dead Center (BTDC).
  6.  
  7. The markings on the pulse wheels of the intake and exhaust camshafts at the left cylinder head must be located centrally in the bores of the camshaft sensors. If not, rotate the engine another revolution.
  8.  
  9. Rotate the engine in the direction of rotation 95 degrees so that it is at 40 degrees After Top Dead Center (ATDC) of cylinder 1.
  10.  
  11. Install the camshafts on the right cylinder head. The marks should point upwards and match with the markings on the cylinder head covers.
  12.  
  13. Rotate the engine in the direction of rotation until the timing marks align at 55 degrees BTDC again. The markings on the pulse wheels of the intake and exhaust camshafts at the left cylinder head must be located centrally in the bores of the camshaft sensors.
  14.  
  15. Install or connect the following:

    Spark plugs
     
    Negative battery cable
     

  16.  
  17. Start the engine and check operation.
  18.  

 
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