Question about GMC Sierra 1500

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Need how to find TDC on 4.3 v-6

Have a '97 GMC Sierra 4.3ltr v-6 Vortex engine. Recently changed a leaking intake manifold gasket. Can't find TDC so i can drop in distributor. Thought i had it but engine won't start. It actually wants to start but misfires. All wiring is correct so no crossed wires. Cannot get distributor lined up correctly to #1 piston.

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  • rcedillo70 Oct 21, 2008

    Thanks for your help emissionwiz. One more thing though, there isn't any markings on the crank pulley, only one line on opposite sides of harmonic balancer. Everytime i find TDC with my finger on the #1 plug, the distributor won't fall pointing to that #1 piston. Am i supposed to make sure that the rotor points to the #1 plug wire on the cap or towards the #1 piston? Very confused. Have tried both ways and no luck with distributor falling where it should. Am i doing something wrong?

  • rcedillo70 Oct 22, 2008

    First of all, thanks for all your recent help.Okay i finally stabbed the distributor in the right place and the rotor is pointing to the #1 wire on the cap. Piston is TDC but it still won't crank. Truck was running good before changing the intake manifold gasket. All electrical connections are good. What else do i try or check? Should i perform a diagnostic check? When the timing was way off , would that cause any damage to the crank position sensor?

  • mollybigdog Nov 26, 2008

    rebuilt 98 gmc jimmy - cant get it to start - tried putting distributor back in many times no luck still no start

  • Anonymous Jan 26, 2009

    have the same problem , 1997 GMC serria , had to change intake gasket . put it all together , and wamm , just turns over , no FIre. played around with it for awhile , got it to fire once but then it just ran for a few sonds , and has not run since , been 2 days and gettin kinda depressed over it now.

  • Rays Performance
    Rays Performance Jan 24, 2014

    hi i was having the same problem after changing intake gasket and i put cam sensor back exactly the way it came 6 or more timesout then decided to try 180 degrees out and it ran perfect dont know why but it worked. i have been a tech for thirty years and own a repair shop.some times the reason doesnt matter if it works go with ithope this helps others having this problem,Ray owner of Rays performance conway NH

  • Anonymous Mar 21, 2014

    I was drive and my truck died when I checked for tdc I found it had jumped I reset it to correct and now its still back firing through the air intake

  • Anonymous Mar 22, 2014

    When engine is warm its hard to start but it starts after 6 to 8 trys



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Remove # 1 plug and stick your finger in the hole, roll the engine over by hand, when you start to feel pressure in the cylinder you are near TDC, just check the crank pulley marks to zero it to TDC mark on pulley.

Posted on Oct 21, 2008

  • yadayada
    yadayada Oct 21, 2008

    Yes the balancer, that line is most likely TDC



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