7.4l(454) Problems

Discussion in 'Chevy Truck Forum' started by ryeja, Apr 15, 2007.

  1. ryeja

    ryeja Senior Member

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    First of all I'm new to the site. Some very good info going around. I have a '97 K2500 7.4l Vortec. I'm having problems starting when up to temp. When cold turns over and fires no problem. Here's what i've done so far. Replaced fuel pump, rotor, cap,wires,plugs, fuel pressure regulator. I'll also mention that when it does start(warm) it cranks over for about 30 secs+(like a Dodge) then smokes a little blue. I've notice m coolant resevoir needs topping every once in a while which tells me i may have a leaking intake gasket. No coolant in the oil so not head gasket. Anyone?
     
  2. junior3382

    junior3382 Senior Member

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    Welcome to the site, and it sounds like a nice truck. And it seems you have a handle on this issue, I would agree that it sounds like the intake gasket, but I would not discount the head gaskets. Sometimes they can leak and not nescesarily internally. If there is blue smoke, it does mean that there is a leak, and there are only so many places it can leak. But I would check the intake gasket first, seem right.
     
  3. ryeja

    ryeja Senior Member

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    Thanks junior3382 for the reply. Since I have to drain the rad anyway to change intake gasket I may as well change head gaskets too. Besides it may be over due as motor has just over 100k.
     
  4. mrjohnwayne

    mrjohnwayne Full Member

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    Check your coil for the starting issue. For the head gaskets do a compression test before tearing the motor down. If all cyinders have good compression no need changing the head gaskets.
     
  5. ryeja

    ryeja Senior Member

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    Thanks mrjohnwayne. I'll definatly be doing a commpression test before pulling the heads. At roughly 60lbs a piece it's alot of manhandling to remove them.
    About the coil, would I not be experiencing problems while driving?
    One other thing mentionable is the lack of power. I've noticed engine performance lacking while pulling my RV.
     
  6. mrjohnwayne

    mrjohnwayne Full Member

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    It depends. Coils can be wierd. In my experiences I have seen them not restart at all hot but run fine hot if you didnt shut the motor off. I have also seen them run fine cold but develop a miss/studder after heating up.
     
  7. ryeja

    ryeja Senior Member

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    Well I tore off the lower intake manifold yesterday and awaiting parts. One thing I found is all the bolts were not torque tight. I'm thinking possibly a small vacuum leak when heads and everything heated up. Checked head bolts and they are torqued to specs. Not sure if this is the original gasket, as I'm 2nd owner, but has chevy part no and stamp on it. Not sure why the bolts were loose. Hope fully will have a solution and running within couple of days.
     
  8. mrjohnwayne

    mrjohnwayne Full Member

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    cool beans. Let us know how it turns out!
     
  9. green72

    green72 New Member

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    man i think we have the same problem, i have a 2000 grew cab 3/4 ton short bed that does the same thing. it starts perfect in the morning,but once it warms up and after its sits for an hour or two it cranks too long,only about 10 seconds thats not very long,but i know somethings not right.i just bought this truck a few weeks ago and of course on the lot it was cold and started fine. i replaced the fuel pressure regulator and that did not help. it has had the intake gaskets changed already.my truck does have 285,000 miles on it but it runs super.i was thinking maybe it was the oil pressure sender,it also acts as a fuel cut off
     
  10. GR8wht2000GMC

    GR8wht2000GMC Full Member

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    me too


    we all semm to have same prob. i have a 2000 crew cab 3/4 ton short bed. same **** and more. i think i need intake gaskets too. i hear this is common on the vortec 454
     

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