4100 engine change. Need input.
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HT4100 4.1, 4.5, 4.9 Discussion, 4100 engine change. Need input. in Cadillac Engine Technical Discussion; Hey guys need some insight to engine swapping. Got an 85 seville with the beloved 4100. Its going strong at ...
  1. #1
    MrDobin is offline Cadillac Owners Fanatic
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    4100 engine change. Need input.

    Hey guys need some insight to engine swapping. Got an 85 seville with the beloved 4100. Its going strong at 91k miles but at a time I will for sure wanna pop a different engine in. What options do I have. I'm in the dark.

    Its a front wheel drive 4.1 seville 85 FYI. Thanks all.

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    steelybill is offline Cadillac Owners Enthusiast
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    Re: 4100 engine change. Need input.

    It seems that the later 4.5 is being used in place of the "beloved" super-high-tech 4100. A little more power I'm told.

    If I get to that point, I'll put a 3.8 Buick in there, and have more room to work on it.

  4. #3
    MrDobin is offline Cadillac Owners Fanatic
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    Re: 4100 engine change. Need input.

    Ya that wouldnt hurt at all. My hope is to find a beater with a solid engine and just take it for parts. Not sure of my chances in finding JUST the compatible engine. Only thing annoying me right now is my coolant being goofy. But according to Carnut its air in the lines so i need to do a little trick to top off the radiator. Annoying wonder of high-tech this thing is, though performs solidly at this point even so. Thanks for the help, all others are welcome to add in.

    By the way, would i need a trani change with the buick engine? i rather avoid that.

  5. #4
    noahsdad's Avatar
    noahsdad is offline Cadillac Owners Connoisseur
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    Re: 4100 engine change. Need input.

    Your biggest problem with any swap is going to be the computers. Because your Seville is integrated so tightly through several systems, the ECM, BCM, OBD, Programmer and the Climate Control Panel, stepping outside the 4.X engine realm is more challenge than it's worth, unless you're also planning on doing a custom dash. The 4.5 is the easiest swap, but still requires a fuel pressure regulator and a bit of tweaking to make it reliable.

  6. #5
    steelybill is offline Cadillac Owners Enthusiast
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    Re: 4100 engine change. Need input.

    Whatever you do, you will need a factory manual. After you get the air out of the cooling system, you might get a lot of use with the car yet.
    I wouldn't count that original engine out just yet.

  7. #6
    MrDobin is offline Cadillac Owners Fanatic
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    Re: 4100 engine change. Need input.

    The car itself in and out is stunning still. Just need to be careful when putting the new in I think.

  8. #7
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    Edahall is offline Cadillac Owners Enthusiast
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    Re: 4100 engine change. Need input.

    Bad news: The 4500 is not going to fit in your car. The 4500 was made to fit transversely and for your car, the engine sits longitudinally. However, you do have some other choices including:
    403 Olds
    350 Olds
    6.2 Diesel
    6.5 Diesel
    5.7 Diesel (Not good choice)
    3.8 Buick V6

    The 403 could be made to work with all the electronics. However, it'll be hard on gas but have good power. The 6.2 diesel would get you 35+ mpg and would have even more power than the 403 with a turbocharger or some head work but would have that diesel clatter.

  9. #8
    pompeypaul is offline Cadillac Owners Member
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    Re: 4100 engine change. Need input.

    wouldn't mind a 350 olds in mine, would it bolt to a 4.1 fwd box, use carb and points dizzy and junk the electronics?

  10. #9
    carnut is offline Cadillac Owners Master
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    Re: 4100 engine change. Need input.

    Using DELO 15/40 diesel grade oil and the cooling system pellets being replaced when the coolant is drained every 2 years would keep this engine running well past 100,000 miles. The 85 was the best of the 4100's best gaskets, best head bolts. Just maintain it.

  11. #10
    steelybill is offline Cadillac Owners Enthusiast
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    Re: 4100 engine change. Need input.

    I agree with carnut. Just maintain it like it should be maintained. Like he said, the oil like diesel 15-40, and coolant maintenance, is what it takes to keep it going. The current oils for gas engines don't have the the anti-wear additives anymore, for flat-tappet cams, like diesel oil does

  12. #11
    MrDobin is offline Cadillac Owners Fanatic
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    Re: 4100 engine change. Need input.

    Sounds good. I put the usual oil in recently but its only been 1200 miles if that so ill put the diesel in next time. Why didn't GM just tell people this type of info when it happened? Are people too lazy to just do a flush and oil change as needed?. Would have saved tons on engine recalls

  13. #12
    MrDobin is offline Cadillac Owners Fanatic
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    Re: 4100 engine change. Need input.

    Before I forget. I noticed a ticking sound during low acceleration. It goes away after hitting 25mph or so though. Read that these builds have sort of extra clearance which can make a slight knock or tick? Can be fixed with extra tran fluid?. I have to find the thread but just curious since I haven't checked whether or not its just my air pump pully rattling from being warped. Thanks again all, your great help.

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