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    Subaru Forester 1998-05

    Timing Belt

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    General Information



    Timing belts are typically only used on overhead camshaft engines. Timing belts are used to synchronize the crankshaft with the camshaft, similar to a timing chain on an overhead valve (pushrod) engine. Unlike a timing belt, a timing chain will normally last the life of the engine without needing service or replacement. Timing belts use raised teeth to mesh with sprockets to operate the valve train of an overhead camshaft engine.

    Whenever a vehicle with an unknown service history comes into your repair facility or is recently purchased, here are some points that should be asked to help prevent costly engine damage:



    Does the owner know if, or when the belt was replaced-
     
    If the vehicle purchased is used, or the condition and mileage of the last timing belt replacement are unknown, it is recommended to inspect, replace, or at least inform the owner that the vehicle is equipped with a timing belt.
     
    Note the mileage of the vehicle. The average replacement interval for a timing belt is approximately 60,000 miles (96,000 km).
     

    Interference Engines

    Engines, chain- or belt-driven, can be classified as either free-running or interference, depending on what would happen if the piston-to-valve timing is disrupted. A free-running engine is designed with enough clearance between the pistons and valves to allow the crankshaft to rotate (pistons still moving) while the camshaft stays in one position (several valves fully open). If this condition occurs normally, no internal engine damage will result. In an interference engine, there is not enough clearance between the pistons and valves to allow the crankshaft to turn without the camshaft being in time.

    An interference engine can suffer extensive internal damage if a timing belt fails. The piston design does not allow clearance for the valve to be fully open and the piston to be at the top of its stroke. If the belt fails, the piston will collide with the valve and will bend or break the valve, damage the piston, and/or bend a connecting rod. When this type of failure occurs, the engine will need to be replaced or disassembled for further internal inspection; either choice costing many times that of replacing the timing belt.

    Inspection




    NOTE
    For manufacturer-s recommended service interval, refer to the maintenance interval chart located in this manual.

    The average replacement interval for a timing belt is approximately 60,000 miles (96,000 km). If, however, the timing belt is inspected earlier or more frequently than suggested, and shows signs of wear or defects, the belt should be replaced at that time.


    WARNING
    Never allow antifreeze, oil or solvents to come into with a timing belt. If this occurs immediately wash the solution from the timing belt. Also, never excessive bend or twist the timing belt; this can damage the belt so that its lifetime is severely shortened.



    Click image to see an enlarged view

    Fig. Never bend or twist a timing belt excessively, and do not allow solvents, antifreeze, gasoline, acid or oil to come into contact with the belt

    Inspect both sides of the timing belt. Replace the belt with a new one if any of the following conditions exist:



    Hardening of the rubber-back side is glossy without resilience and leaves no indentation when pressed with a fingernail
     
    Cracks on the rubber backing
     
    Cracks or peeling of the canvas backing
     
    Cracks on rib root
     
    Cracks on belt sides
     
    Missing teeth or chunks of teeth
     
    Abnormal wear of belt sides-the sides are normal if they are sharp, as if cut by a knife.

    Click image to see an enlarged view

    Fig. Clean the timing belt before inspection so that imperfections or defects are easier to recognize



    Click image to see an enlarged view

    Fig. Inspect the timing belt for damage, such as a broken or missing tooth, which may be due to a damaged pulley



    Click image to see an enlarged view

    Fig. Back surface worn or cracked from a possible overheated engine or interference with the belt cover



    Click image to see an enlarged view

    Fig. Side wear from improper installation or a defective pulley plate



    Click image to see an enlarged view

    Fig. Worn teeth from excessive belt tension, camshaft or distributor not turning properly, or fluid leaking on the belt

     

    If none of these conditions exist, the belt does not need replacement unless it is at the recommended interval. The belt MUST be replaced at the recommended interval.


    WARNING
    On interference engines, it is very important to replace the timing belt at the recommended intervals, otherwise expensive engine damage will likely result if the belt fails.

    Removal & Installation



    2.5L DOHC Engine

    When servicing the timing belt, note the following:



    The intake and exhaust camshafts can be rotated independently when the timing belt is removed. If the intake and exhaust valves are lifted off of their seats simultaneously, their heads will contact each other, possibly causing damage.
     
    When the timing belt is removed, the camshafts are positioned so that none of the valves are lifted off of their seats, resulting in a -zero-lift- position.
     
    The left-hand cylinder head camshafts must be rotated from the -zero-lift- position as little as possible when orienting it for timing belt installation, otherwise possible valve head interference may occur.
     
    Never allow the camshafts to rotate in the direction shown in the accompanying illustration, which would cause both the intake and exhaust valves to lift simultaneously, causing interference.

    Click image to see an enlarged view

    Fig. If the camshafts must be rotated, do not turn them in toward each other (upper diagram); only rotate them away from each other (lower diagram)-Subaru Forester 2.5L DOHC engine



    Click image to see an enlarged view

    Fig. Timing belt routing and timing belt guide (manual transmission equipped vehicles only) location-Subaru Forester 2.5L DOHC engine



    Click image to see an enlarged view

    Fig. Before removing the timing belt, turn the crankshaft sprocket until all of the alignment marks are aligned as indicated-Subaru Forester 2.5L DOHC engine

     

    1. Remove all necessary components to gain access to the timing belt.
    2.  
    3. If equipped with manual transmissions, loosen the 2 timing belt guide mounting bolts, then separate the guide from the engine block.
    4.  
    5. If the directional arrow and alignment marks on the timing belt are faded, and the belt is to be reused, remark the belt with white paint or a grease pencil as follows:
      1. Using a Subaru tool No. ST-499987500 Crankshaft Socket, or equivalent, installed on the crankshaft sprocket, rotate the crankshaft until the crankshaft sprocket, left-hand exhaust camshaft sprocket, left-hand intake camshaft sprocket, right-hand intake camshaft sprocket and right-hand exhaust camshaft sprocket timing mark notches are aligned with the respective marks on the belt cover and engine block.

        Click image to see an enlarged view

        Fig. On models equipped with a manual transmission, loosen the 2 timing belt guide bolts and separate the guide from the engine block-Subaru Forester 2.5L DOHC engine



        Click image to see an enlarged view

        Fig. If the original marks on the timing belt are worn or faded, make new alignment marks in the positions indicated-Subaru Forester 2.5L DOHC engine

      2.  
      3. Make alignment and/or arrow marks on the timing belt in relation to the sprockets as indicated in the accompanying illustration.

        Z1: 54.5 tooth length
         
        Z2: 51 tooth length
         
        Z3: 28 tooth length
         

      4.  

    6.  
    7. Loosen the center bolt from the timing belt idler pulley, then remove the idler pulley from the engine block.
      WARNING
      After removing the timing belt, DO NOT rotate the camshafts. Damage to the valves may occur.

    8.  
    9. Carefully remove the timing belt from all of the sprockets.

      Click image to see an enlarged view

      Fig. It is necessary to remove the automatic adjuster assembly and reset the pushrod for timing belt installation-Subaru Forester 2.5L DOHC engine

    10.  
    11. Remove the automatic belt tension adjuster assembly as follows:
      1. Remove the 2 timing belt idler pulleys, as indicated in the accompanying illustration.
      2.  
      3. Loosen the automatic tension adjuster assembly mounting bolts, then separate the adjuster assembly from the engine block.
      4.  

    12.  

    To install:


    WARNING
    Do not allow oil, grease, or coolant to come in contact with the timing belt. If this occurs, quickly and thoroughly remove all traces of the compound. Also, never bend the timing belt sharply; the minimum bending radius is 2.36 in. (60mm).



    Click image to see an enlarged view

    Fig. Never bend the timing belt into a radius tighter than 2.36 in./60mm (h), otherwise it will be damaged beyond use-Subaru Forester 2.5L DOHC engine



    Click image to see an enlarged view

    Fig. Use a vertical press to push the adjuster rod into its housing until it is flush with the assembly-s outer surface . . . -Subaru Forester 2.5L DOHC engine



    Click image to see an enlarged view

    Fig. . . . then insert a 0.08 in. (2mm) diameter pin or Allen wrench into the housing and rod holes to hold it in position-Subaru Forester 2.5L DOHC engine

    1. Inspect the camshaft and crankshaft sprocket teeth for abnormal or excessive wear or scratches. Ensure there is no free-play between the sprocket and the key. Inspect the crankshaft sprocket sensor notch for damage or contamination with debris or dirt.
      NOTE
      When preparing the automatic tension adjuster assembly for installation, adhere to the following points:



      Always use a vertical press, rather than a horizontal press or vise, to depress the adjuster assembly rod
       
      Depress the adjuster rod in a vertical position ONLY
       
      Depress the adjuster rod slowly (taking more than 3 minutes) with a force of 66 lbs. (30 kg)
       
      Do not allow the press force to exceed 2205 lbs. (1000 kg)
       
      Press the adjuster rod in as far as the end surface of the cylinder-do not press the rod into the cylinder, which may cause damage to the assembly
       
      Do not release the press force from the rod until the stopper pin is completely inserted in the cylinder
       

    2.  
    3. Prepare the automatic timing belt tension adjuster assembly for installation as follows:
      1. Position the adjuster assembly in a vertical press.
      2.  
      3. Slowly depress the adjuster rod with a force of 66 lbs. (30 kg) until the hole in the rod is aligned with the hole in the adjuster cylinder housing.
      4.  
      5. Insert a 0.08 in. (2mm) diameter stopper pin or Allen wrench through the hole in the cylinder housing and rod, then slowly release the press force from the adjuster rod.
      6.  

    4.  
    5. Install the adjuster assembly onto the engine block.
    6.  
    7. Install timing belt idler pulley No. 2 on the engine block.
    8.  
    9. Install the timing belt idler pulley No. 1 on the engine block.
    10.  
    11. If the camshaft and crankshaft timing marks are no longer aligned, perform the following:
      1. Position the crankshaft sprocket so that its mark is aligned with the mark on the oil pump cover on the engine block.

        Click image to see an enlarged view

        Fig. If the camshaft sprockets are no longer aligned, rotate the crankshaft sprocket until the marks are aligned . . .-Subaru Forester 2.5L DOHC engine



        Click image to see an enlarged view

        Fig. . . . then turn the right-hand exhaust camshaft until the single line mark is aligned with the notch in the belt cover-Subaru Forester 2.5L DOHC engine



        Click image to see an enlarged view

        Fig. Spin the right-hand intake camshaft sprocket so that the single line mark is aligned with the notch in the belt cover-at this point, the double line marks on both right-hand camshaft sprockets must be aligned-Subaru Forester 2.5L DOHC engine



        Click image to see an enlarged view

        Fig. Rotate the left-hand exhaust camshaft until the single line mark is aligned with the notch in the belt cover . . .-Subaru Forester 2.5L DOHC engine



        Click image to see an enlarged view

        Fig. . . . then align the single line mark on the left-hand intake sprocket with the belt cover notch-Subaru Forester 2.5L DOHC engine



        Click image to see an enlarged view

        Fig. After orienting all 5 sprockets, the alignment marks should be positioned as shown-Subaru Forester 2.5L DOHC engine

      2.  
      3. Align the single line mark on the right-hand exhaust camshaft sprocket with the notch on the belt cover.
      4.  
      5. Rotate the right-hand intake camshaft so that the single line mark is aligned with the notch on the belt cover.
        NOTE
        At this point, the double line marks on both right-hand camshaft sprockets should be aligned.

      6.  
      7. Turn the left-hand exhaust (lower) camshaft counterclockwise (as viewed from the front of the engine) until the single line mark is aligned with the notch on the belt cover.
      8.  
      9. Position the single line mark on the left-hand intake camshaft sprocket so that it is aligned with the notch on the belt cover. When rotating the camshaft, do so only in a clockwise direction (as viewed from the front of the engine).
        NOTE
        At this point, the double line marks on both left-hand camshaft sprockets should be aligned.

      10.  
      11. Ensure the timing marks are aligned as shown in the accompanying illustration. If they are not, repeat Substeps 12a through 12e until they are properly aligned.
      12.  

    12.  
    13. Install the timing belt around the camshaft, crankshaft and idler pulleys so that the positioning marks on the timing belt are aligned with the marks on the sprockets as follows:
      1. Position the timing belt on the crankshaft sprocket so that the marks are aligned.
      2.  
      3. Route the belt down and under the left-hand, upper idler pulley, then up and around the left-hand intake camshaft sprocket, ensuring the camshaft sprocket mark is aligned with the mark on the belt.
      4.  
      5. Route the belt down and around the left-hand exhaust camshaft sprocket, making sure the marks are properly aligned, then up and over the first lower idler pulley and down and around the second lower idler pulley.

        Click image to see an enlarged view

        Fig. When installing the timing belt, be sure to route it in the proper order (a through e), and ensure that all of the matchmarks are properly aligned-Subaru Forester 2.5L DOHC engine

      6.  
      7. While holding the timing belt on the inner, left-hand, lower idler pulley, route the other side of the timing belt (from the crankshaft sprocket) down and under the right-hand upper idler pulley.
      8.  
      9. Route the timing belt up and around the right-hand intake camshaft sprocket so that the belt and sprocket marks are aligned.
      10.  
      11. Position the belt down and around the right-hand exhaust camshaft sprocket, ensuring the positioning marks are aligned.
      12.  

    14.  
    15. Install the right-hand lower idler pulley so that the timing belt is routed over the top side of it.
      NOTE
      Once the belt is completely installed on all of the pulleys and sprockets, ensure that the positioning marks are still all aligned.

    16.  
    17. After ensuring all of the marks are still aligned, use a pair of pliers to withdraw the stopper pin or Allen wrench from the adjuster assembly housing.
    18.  
    19. On models with manual transmissions, perform the following:
      1. Install the timing belt guide by temporarily tightening the mounting bolts.
      2.  
      3. Position the timing belt guide so that there is 0.019-0.059 in. (0.5-1.5mm) clearance between the timing belt and the belt guide.

        Click image to see an enlarged view

        Fig. On models equipped with manual transmissions, ensure the timing belt-to-guide clearance (arrows) is correct before tightening the mounting bolts-Subaru Forester 2.5L DOHC engine

      4.  
      5. Tighten the guide mounting bolts securely, then double check the guide clearance.
      6.  

    20.  
    21. Install the timing belt covers and all remaining engine components.
    22.  

     
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