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Timing belt went at about 25 mph

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  • Timing belt went at about 25 mph

    Hello, first post here. I was wondering, since this is an interference engine do you think the pistons hit the valves at this speed. I can see where the teeth came off, right after the intermediate. If these did hit what would you think the cost would be on parts and what parts need to be replaced?

    Thanks

  • #2
    These engines are not interference at low rpm, so road speed has nothing to do with the possibility of the valves being bent. They do become interference at high rpm (probably due to valve float), so if say you were on it hard when the belt went, yeah you could have bent valves and the only way to tell how many you need (to find the price out) is take it apart to find out how many valves you trashed if your only replacing the bad ones. If the belt went at low rpms, grab a new belt, slap it on and go because it will be fine.
    -60v6's 2nd Jon M.
    91 Black Lumina Z34-5 speed
    92 Black Lumina Z34 5 speed (getting there, slowly... follow the progress here)
    94 Red Ford Ranger 2WD-5 speed
    Originally posted by Jay Leno
    Tires are cheap clutches...

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    • #3
      How can it become interference at high rpm? It either is or isn't.
      sigpic New 2010 project (click image)
      1994 3100 BERETTA. 200,000+ miles
      16.0 1/4 mile when stock. Now ???
      Original L82 Longblock
      with LA1, LX9, LX5 parts
      Manifold-back 2.5" SS Mandrel Exhaust. Hardware is SS too.

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      • #4
        It is non interference because you can time the motor with a piston at TDC. Its interference because rod stretch and/or valve float will cause the valves to make contact if the belt breaks. If it didn't break at WOT, then its most likely fine.

        It is AND it isn't.
        Ben
        60DegreeV6.com
        WOT-Tech.com

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        • #5
          Well valve float isn't going to matter if the cam is holding open a valve because it's not turning. Rod stretch however will matter.
          sigpic New 2010 project (click image)
          1994 3100 BERETTA. 200,000+ miles
          16.0 1/4 mile when stock. Now ???
          Original L82 Longblock
          with LA1, LX9, LX5 parts
          Manifold-back 2.5" SS Mandrel Exhaust. Hardware is SS too.

          Comment


          • #6
            Originally posted by IsaacHayes View Post
            Well valve float isn't going to matter if the cam is holding open a valve because it's not turning. Rod stretch however will matter.
            Well the float could happen at the exact moment the belt lets go and the piston is coming up, making it interference at that point in time. But at any rate, the belt that shredded (literally) on the 91 when Ben was driving it went at about 30-40 mph if my memory serves me.
            -60v6's 2nd Jon M.
            91 Black Lumina Z34-5 speed
            92 Black Lumina Z34 5 speed (getting there, slowly... follow the progress here)
            94 Red Ford Ranger 2WD-5 speed
            Originally posted by Jay Leno
            Tires are cheap clutches...

            Comment


            • #7
              sorry it took me a while to get back on here. Well, I have everything off down to the valve covers and got the old belt off, OMG it was shredded and looked like it was dryrotted. I got all the stuff I need, I had a guy to help me with the timing but it looks like im gonna try myself. Im having a problem finding the timing marks but I guess ill do some more research this is my first timing so. I really am caught between, I mean i could go ahead and take the heads off to see if theres damage but if there isnt theres 300$ on gaskets if there is Id save myself another headache later.

              wish me luck

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              • #8
                Well ended up buying a cam sprocket tool and got everything done. Only problem I had to rig up my tensioner with a washer behind, I snapped off the corner of the bracket could not remove the torx bolts that hold it in place. Ill have to take it to a dealer or something, but i did get the timing done and everything put back together

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                • #9
                  how is the washer being used in this situation?
                  Robert
                  ---------------------------------------------------
                  96 Grand Prix SE 3100 202,000 miles
                  New Rebuilt 3100
                  New Rebuilt 4T60-E
                  Exhaust
                  Drilled/Slotted Rotors


                  95 Grand Prix GTP 177,000 miles
                  White
                  3" Magnaflow Catback
                  Lowered 2" Eibach in front Brichmount Rear
                  94-96 Hi-Po 5 Stars on 245/50/16


                  90 Pontiac Turbo Grand Prix
                  5 Speed Swapped
                  127,000
                  Spec Stage 3 Clutch
                  230,000 mile Getrag 282
                  Emissions Deleted
                  Brand new Engine 1,000 Miles
                  Fully Custom Built car

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                  • #10
                    It made up the slack between the broken part and the front cover of the engine. The tensioner is still seated in both parts. I snugged the tension plate into the whole thing, though id like to get it replaced eventually.

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