One more ? on 89 740 GL....

Discussion in 'Volvo 740' started by Geronimo, Oct 17, 2005.

  1. Geronimo

    Geronimo Guest

    (see my post below this one)

    I think the timing has also jumped off. Has happened before after
    repeated heavy cranking from other problems. Problem is, the harmonic
    balancer was replaced, and I cannot see any mark/notch or dot on it.
    Don't see a notch on the crankshaft sprocket (behind damper) either!
    Neither is there any kind of +/- 0-degree index to reference a notch
    to! On the cam sprocket, there is no problem. The dot that you line up
    with the 11 o'clock mark on the upper rear of the timing belt cover
    is clearly visible.
    I noticed that the cam sprocket has points, two I think, going
    through 360 degress......that it just wants to "drop" into, seems like
    these points are at 11 o'clock and 5 o'clock.

    The Haynes manual shows that when timed correctly, the cam is at
    abt. 11 o'clock, and the crankshaft/damper pulley notch is also at
    abt. 11 o'clock. But with no reference on damper pulley, I can't do
    the procedure called for in the Haynes manual... I guess all I can do
    is take the no 1 spark plug out and use a screwdriver to feel when the
    piston is at TDC. Will I be able to get it timed well enough this way?
    Or will I still need to get it tweaked exactly right by a pro?
    Thanks for the help....Jim
    Geronimo, Oct 17, 2005
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  2. Geronimo

    Randy G. Guest

    Pull all the plugs and put your finger over the #1 spark plug hole.
    You will feel it come up on compression while manually turning the
    crank pulley. Use a wooden dowel, plastic rod, or other similar tool
    to feel when the piston is all the way up. Do not use a metal tool
    becasue if you cause any scratches on the piston, the metal burr can
    cause preigition detonation (ping and knock).

    To find TDC exactly, turn the motor back to where you feel the piston
    go down a bit. mark this position on the pulley. Rotate it in the
    opposite direction and feel where it begins to go down a bit. Mark
    that position. Midway between the two marks should be poretty darn
    close to TDC. Mark the balancer with a scribe along a convenient place
    that aligns with a mark on the motor.

    You know the rest...

    __ __
    Randy & \ \/ /alerie's
    '90 245 Estate - '93 965 Estate
    "Shelby" & "Kate"
    Randy G., Oct 17, 2005
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  3. Geronimo

    Geronimo Guest

    I am still a little unclear on this. If I line up the cam sprocket
    index dots at their 11 o'clock position, and then find exact TDC as
    you said to do, this gaurantees that it is set up for TDC on the
    compression stroke, not exhaust stroke (as confirmed by air pressure
    building up against the fingertip)?
    Geronimo, Oct 18, 2005
  4. Geronimo

    User Guest

    The outer guard sheave on the crankshaft wheel has a notch that aligns
    with the protruded index line on the front of the engine. The dot on the
    camshaft aligns with a notch cut in the front of the cam cover. If your
    distributor is in the back of the head the dot on the jack shaft pulley
    is irrelevant otherwise use the single line markings on the new belt to
    stablish the correct location.

    Install the belt starting at the crankshaft, around the jackshaft and
    around the camshaft so that all the slack is on the tensioner side.
    Slacken the nut on the tensioner and pry it against the spring all the
    way to the loosest position and tighen the nut (Probably shuld be the
    first step). Use a clothes pin clamp to hold ther belt stationary on the
    cam wheel and slide the belt over the tensioner pulley. Loosen the nut
    and let the the tensioner find its own center. Tighten the nut. Check
    your timing marks for proper alignment. Install the crank bolt and turn
    the motor through 2 or four revolutions to be sure nothing is binding.
    Inspect the timing mark alignment one more time. If there was too much
    slack on the left side of the motor (right side as you face it) the
    tensioner will pull the crank pulley clockwise as you face the motor and
    your marks won't line up.

    In four cylinder history, motors set up with the crank on TDC and the
    mark on the cam gear or sprocket if a chain driven motor facing each
    other. This would be #4 compression/firing. But when you put the mark on
    top, since the pulleys are relatively far apart using this method is
    difficult, so a mark was placed topside to facilitate set up. In order
    to do this the motor had to be turned another 180 degrees to put the cam
    mark at the top, hence the motor sets up on #1 compression/firing. I
    haven't ever seen a bentley manual so I don't know what they are talking
    about with 11 o'clock and such. The marks make a straight run down the
    center line of the motor.

    So I guess the short answer to your question is, "yes."

    User, Oct 18, 2005
  5. Geronimo

    James Sweet Guest

    The compression stroke and the exhaust stroke are identical as far as the
    crankshaft is concerned, so long as you line up the rotor in the distributor
    correctly you'll be fine.
    James Sweet, Oct 19, 2005
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