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    1993 Acura Vigor 2.5L FI 5cyl

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    GM Buick/Oldsmobile/Pontiac/Full-Size 1975-1990 Repair Guide

    Timing Chain

    Print

    REMOVAL & INSTALLATION



    See Figures 1, 2, 3, 4, 5 and 6

    Buick Built V6 and V8
    1. Disconnect the negative battery cable. Remove the front cover as previously outlined.
    2.  
    3. Align the timing marks on the sprockets.
    4.  
    5. Remove the camshaft sprocket bolt without changing the position of the sprocket. On the V6 and 455, remove the oil pan.
    6.  
    7. Remove the front crankshaft oil slinger.
    8.  
    9. On the 350, remove the crankshaft distributor drive gear retaining bolt and washer. Remove the drive gear and the fuel pump eccentric. On the V6 and the 455, remove the camshaft sprocket bolts.
    10.  
    11. Using two large prybars, carefully pry the camshaft sprocket and the crankshaft sprocket forward until they are free. Remove the sprockets and the chain.
    12.  
    13. Remove the crankshaft sprocket using a jaw puller or equivalent tool.
    14.  

    To install:
    1. Make sure, with sprockets temporarily installed, that No. 1 piston is at top dead center and the camshaft sprocket O-mark is straight down and on the centerline of both shafts.
    2.  
    3. Remove the camshaft sprocket and assemble the timing chain on both sprockets. Then slide the sprockets-and-chain assembly on the shafts with the O-marks in their closest together position and on a centerline with the sprocket hubs.
    4.  
    5. Assemble the slinger on the crankshaft with I.D. against the sprocket, (concave side toward the front of engine). Install the oil pan, if removed.
    6.  
    7. On the 350, slide the fuel pump eccentric on the camshaft and the Woodruff key with the oil groove forward. On the six cylinder and the 455, install the camshaft sprocket bolts.
    8.  
    9. Install the distributor drive gear.
    10.  
    11. Install the drive gear and eccentric bolt and retaining washer Torque to 40-55 ft. lbs. (54-75 Nm). Turn the crankshaft over twice to see if the timing marks align. If they do not align, the chain is not in the right position and will have to be realigned.
    12.  
    13. Install the timing case cover. Install a new seal by lightly tapping it in place. The lip of the seal faces inward. Pay particular attention to the following points.
      1. Remove the oil pump cover and pack the space around the oil pump gears completely full of petroleum jelly. There must be no air space left inside the pump. Reinstall the pump cover using a new gasket.
      2.  
      3. The gasket surface of the block and timing chain cover must be clean and smooth. Use a new gasket correctly positioned.
      4.  
      5. Install the chain cover being certain the dowel pins engage the dowel pin holes before starting the attaching bolts.
      6.  
      7. Lube the bolt threads before installation and install them.
      8.  
      9. If the vehicle has power steering the front pump bracket should be installed at this time.
      10.  
      11. Lube the O.D. of the harmonic balancer hub before installation to prevent damage to the seal when starting the engine.
      12.  

    14.  

    The V6 engine has two timing marks on the harmonic balancer. A 1 in. (25.4mm) long, thin scribe mark is used for strobe light timing. Another mark, 4 in. (102mm) back, has a wider slot and is about1/2in. (12.7mm) long. This mark is used for magnetic pick-up timing.

    Pontiac Built Engines
    1. Disconnect the negative battery cable. Remove the timing chain cover as previously outlined in this section.
    2.  
    3. Remove the camshaft bolt, fuel pump eccentric and bushing.
    4.  
    5. Align the timing marks to simplify proper positioning of the sprockets during reassembly.
    6.  
    7. Slide the timing chain and camshaft gear off at the same time.
    8.  

    If you intend to remove the gear on the crankshaft you will need a puller to do so.

    To install:
    1. Install the new timing chain and or sprockets, making sure the marks on both sprockets are exactly on a straight line passing through the shaft centers. The camshaft should extend through the sprocket so that the hole in the fuel pump eccentric will locate on the shaft.
    2.  
    3. Install the fuel pump eccentric and bushing. Install the retainer bolt and tighten it to 40 ft. lbs. (54 Nm).
    4.  
    5. Reinstall the timing gear cover, water pump, and harmonic balancer. Remember to install a new O-ring in the water passage. Connect the negative batter cable and check for proper operation.
    6.  

    When reassembling the timing case cover, extra care should be taken to make sure that the oil seal between the bottom of the timing case cover and the front of the oil pan is still good. Gasket cement should be used at the joint to prevent oil leaks.

    Oldsmobile Built Engines
    1. Disconnect the negative battery cable.
    2.  
    3. Remove the timing case cover and take off the camshaft gear.
    4.  

    The fuel pump operating cam is bolted to the front of the camshaft sprocket and the sprocket is located on the camshaft by means of a dowel.

    1. Remove the oil slinger, timing chain, and the camshaft sprocket. If the crankshaft sprocket is to be replaced, remove it also at this time. Remove the crankshaft key before using the puller. If the key can not be removed, align the puller so it does not overlap the end of the key, as the keyway is only machined part of the way into the crankshaft gear.
    2.  

    To install:
    1. Reinstall the crankshaft sprocket being careful to start it with the keyway in perfect alignment since it is rather difficult to correct for misalignment after the gear has been started on the shaft. Turn the timing mark on the crankshaft gear until it points directly toward the center of the camshaft. Mount the timing chain over the camshaft gear and start the camshaft gear up on to its shaft with the timing marks as close as possible to each other and in line between the shaft centers. Rotate the camshaft to align the shaft with the new gear.
    2.  
    3. Install the fuel pump eccentric with the flat side toward the rear.
    4.  
    5. Drive the key in with a hammer until it bottoms.
    6.  
    7. Install the oil slinger.
    8.  
    9. Install the timing cover, vibration damper, belts, fan, connect the negative battery cable. Start the engine and check for normal operation.
    10.  

    Any time the timing chain and gears are replaced on the diesel engine it will be necessary to retime the engine.

    Chevrolet Built Engines

    To replace the chain, remove the radiator, water pump, the harmonic balancer and the crankcase front cover. This will allow access to the timing chain. Crank the engine until the timing marks on both sprockets are nearest each other and in line between the shaft centers. Then take out the three bolts that hold the camshaft gear to the camshaft. This gear is a light press fit on the camshaft and will come off easily. It is located by a dowel.

    The chain comes off with the camshaft gear.

    A gear puller will be required to remove the crankshaft gear.

    Without disturbing the position of the engine, mount the new crankshaft gear on the shaft, and mount the chain over the camshaft gear. Arrange the camshaft gear in such a way that the timing marks will line up between the shaft centers and the camshaft locating dowel will enter the dowel hole in the cam sprocket.

    Place the cam sprocket, with its chain mounted over it, in position on the front of the vehicle and pull up with the three bolts that hold it to the camshaft.

    After the gears are in place, turn the engine two full revolutions to make certain that the timing marks are in correct alignment between the shaft centers.

    End play of the camshaft is zero.



    Click image to see an enlarged view

    Fig. Fig. 1: Buick and Oldsmobile built engine valve timing marks; except Olds 400 V8



    Click image to see an enlarged view

    Fig. Fig. 2: Pontiac built V8 and Oldsmobile 400 V8 valve timing marks



    Click image to see an enlarged view

    Fig. Fig. 3: Chevrolet built engine valve timing marks



    Click image to see an enlarged view

    Fig. Fig. 4: The timing chain can be accessed after removing the timing chain cover



    Click image to see an enlarged view

    Fig. Fig. 5: Before removing the timing chain, make sure the valve timing marks are properly aligned



    Click image to see an enlarged view

    Fig. Fig. 6: Removing the camshaft sprocket attaching bolt and fuel pump eccentric

     
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