Timing belt/water pump replacement question.. specifically timing

Discussion in 'Gen 1 & 2 - Engine, Exhaust, Drive Line & AC syste' started by Jaden01, Nov 24, 2020.

  1. Jaden01

    Jaden01 New Member

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    We are in the middle of our water pump replacement, 91 SHO 79k miles. The timing belt was replaced eight years ago(6k miles ago) and is in surprisingly good shape. We got the timing belt off, the old water pump off, the new water pump on, and ended up dropping a screw behind the crankshaft gear. To get it out we had to manually turn the crank so no issue there.

    My question is when we go to put the timing belt on, we need to adjust the timing again, since the cams and cranks are no longer aligned. Its my understanding this is a non intereference engine, so can we just manually spin the cam gears to their marks, and then turn the crank to its mark, and put the belt on? Am I over thinking this, or is it that simple?

    Tomorrow we are going to fill the system with coolant, and start putting her back together, and I know obviously we need to have the timing perfect so she runs right.
     
    Jaden01, Nov 24, 2020
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  2. Irish Pride

    Irish Pride Irish Inside Staff Member Super Moderators

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    Yes, just rotate each until they line up with their corresponding marks. The rear cam will be difficult to get right but once it is in the correct position it will stay in place.

    Quick tip, use the timing belt to rotate the cam sprockets into place. Just wrap it around each sprocket one at a time and turn it by hand.

    To set the tension on the timing belt, loosen the nut on the tensioner and it will spring into position. Manually rotate the crank 3 full rotations and then tighten the nut to lock the tensioner into place.

    -Chad
     
    Irish Pride, Nov 24, 2020
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  3. Old Stang

    Old Stang Member

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    ... Genius!
     
    Old Stang, Nov 25, 2020
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  4. rubydist

    rubydist SHO Master Staff Member Super Moderators

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    I have a strap wrench that I would use for that.
     
    rubydist, Nov 25, 2020
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  5. Jaden01

    Jaden01 New Member

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    Thanks a lot, we are looking forward to getting her back on the road. This has been a learning experience indeed.
     
    Jaden01, Nov 25, 2020
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  6. Jaden01

    Jaden01 New Member

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    Guys I either thinkn we didnt have the crank sensor close enough, or have the timing wrong. We put the engine back together, and turn her over, and nothing happens. No attempt to fire at all, after doing this a few times, I noticed "vapor" coming from the air box, im assuming fuel mist.

    My thoughts are 1) we need to tear back down far enought to properly install the crank sensor(I saw the .30 recommendation with feeler gauges.

    And 2) even though we meticulously lined up the timing marks on the cams and crankshaft, is there a chance that we need to spin the rear cam another full rotation so they open/close as a team correctly? Am I overthinking this, or is there a chance we do not have them in sync anymore? All I can hear when trying to start the car is the starter, no real "engine" noises at all. The only reason I think this is because of the fuel mist coming from the airbox.

    Hoping someone can help.
     
    Jaden01, Nov 29, 2020
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  7. rubydist

    rubydist SHO Master Staff Member Super Moderators

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    Most likely you have the gap wrong on the sensor.

    If you have the timing marks lined up, then the cam timing is correct - there is no change to rotate one of the cams one additional revolution.

    The other common thing to go wrong is the intake manifold and engine are not grounded properly. The crossover pipe needs to be grounded for the DIS to work, and it is easy to forget that ground strap or not get it installed with a good ground, so check that again too.
     
    rubydist, Nov 29, 2020
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  8. zoomlater

    zoomlater SHO Member Supporting Member

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    Is the engine just spinning, not turning over? You might have the timing belt on backwards. I had this issue on my 92 when a front 60K was done. The belt was on backwards and the three spots lined up, but it would just spin. Take a look at step 16 and note the wording directions in the picture.

    There is a fourth mark that will line up as well. If I recall, there is a mark on the oil pump, have to look on the underside.
     

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    Last edited: Nov 29, 2020
    zoomlater, Nov 29, 2020
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  9. zoomlater

    zoomlater SHO Member Supporting Member

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    Take a look at figure 122, you can see the four marks that will line up
     

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    zoomlater, Nov 29, 2020
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