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  1. #1

    desperate... 3100 engine confusion

    Daughters boyfriend has 98 grand prix v6 engine went out. "mechanic" ( and i use that term loosely at this point) said go to pull-a-part get 3100 engine out of 98 grand prix with letter 'M' in VIN number. Husband did this. Even says 3100 on intake. 3 weeks later... "mechanic" says he pulled wrong engine. Says the engine in the car has aluminum heads and the one my husband pulled does not. Are there 2 different 3.1 or 3100 engines or what the heck is going on here? Desperate for help. Thanks
    Last edited by blueshadow39; 07-13-2011 at 12:46 PM.

  2. #2
    MonteCarloDude's Avatar
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    The 98 grand prix should have the 3100, all 3100's have aluminum heads.

    Said mechanic does not know what the hell he is talking about. As long as the 3100 is out of a 96 or newer car there should no problems swapping it in.
    Last edited by MonteCarloDude; 07-13-2011 at 01:20 PM.
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    Quote Originally Posted by RobertISaar View Post
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    blueshadow39 (07-13-2011)

  4. #3
    We didn't know if there were two different engines... one with aluminum & one without or whats goin on. My husband said same thing you just did. This guys saying the water pump isn't even in the same spot and because this 'new' engine doesn't have aluminum heads that nothing will line up. Is it possible that the grand prix we pulled the engine from maybe didn't have the original motor in it? It says 3100 on intake but is this still a possibility? I apologize for my lack of engine knowledge but so very much appreciate your help!

  5. #4

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    sounds like you have a 3800 motor. the only answer is pictures....


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    If it has "3100 SFI V6" cast into the intake manifold, it is a VIN M, aluminum head V6 engine. period.

    Here's what it should look like basically:
    http://carad.ebayimg.com/i19/03/a/000/77/b4/ef32_4.JPG

    The 3800 V6 would look like this:
    http://images.gtcarlot.com/pictures/47349424.jpg

    I believe the 3800 has iron heads.
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  7. #6
    Quote Originally Posted by Crazy K View Post
    sounds like you have a 3800 motor. the only answer is pictures....
    this is whats in the car 3.1L V6 FI OHV..mechanic says it has aluminum heads
    used engine we pulled came out of 98 grand prix says 3100 on engine.. mechanic says it does not have aluminum heads
    can't get pictures mechanic has it in his shop.
    trying to figure out if he is an idiot or not before we go over there because we want to make sure we know what we're talking about so we don't look like idiots too.

  8. #7
    RobertISaar's Avatar
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    there were two different 3100s made, small port and large port, both had aluminum heads, main difference between them was the upper and lower intakes were slightly different.

    98 grand prixs had the OPTION of a 3800, which would have iron heads, however they look nothing like the 3100s.

    "mechanic" sounds like a dumbass.
    King of Code
    1995 Monte Carlo LS 3100, 4T60E... for now, future plans include driving it until the wheels fall off!



  9. #8
    Quote Originally Posted by MonteCarloDude View Post
    The 98 grand prix should have the 3100, all 3100's have aluminum heads.

    Said mechanic does not know what the hell he is talking about. As long as the 3100 is out of a 96 or newer car there should no problems swapping it in.
    i guess this mainly answers our question. we were tying to determine if there were two different types of this engine. one with aluminum heads and one with iron heads. thanks guys!

  10. #9
    MonteCarloDude's Avatar
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    Quote Originally Posted by blueshadow39 View Post
    i guess this mainly answers our question. we were tying to determine if there were two different types of this engine. one with aluminum heads and one with iron heads. thanks guys!
    Your most welcome. I hope everything works out and you guys are able to get it back on the road soon.
    1998 Monte Carlo LS, Dark Toreador Metallic.
    P&P 3400 UIM, LIM, And TB, 180*T-Stat.
    Custom FWI. Dyno Tuned.
    Polyurethane Dogbone Engine Mounts.
    Custom Shift Kit / Dexron VI.
    GMPP Front And Rear STB's, SS Rear Brake Lines.
    Quote Originally Posted by RobertISaar View Post
    i sail the mighty seas of the intertubez with me trusty plastic bodied ship. the 0s and 1s that i seek, they cannot evade me.

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