HT 4100 4.1 motor problems - giving up
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HT4100 4.1, 4.5, 4.9 Discussion, HT 4100 4.1 motor problems - giving up in Cadillac Engine Technical Discussion; I have a 1985 Fleetwood Brougham which is loaded, and even has a moonroof that works. When I test drove ...
  1. #1
    Korky519 is offline Cadillac Owners Member
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    HT 4100 4.1 motor problems - giving up

    I have a 1985 Fleetwood Brougham which is loaded, and even has a moonroof that works. When I test drove the car three years ago, it rode wonderfully but I soon learned after buying it that it definitely did not like the highway! It ticks after a highway drive and a slight bottom end knock can be heard, depending on how long it's driven on the highway. However, the car has run like that for the entire length of my ownership, and I've never broken down in it. The motor's noises have not become any louder over time, either. Some have suggested I just keep driving it like that, but it is worrisome on trips, to say the least. There is some rust, but other than that the car is worth putting in a motor. My question is if anybody knows if the 4.1 or 4.5 replacements are even better, and worth the $4,000 I'm being quoted for the installation. I'm told those are the only motors that can be put in due to the bolt patterns, etc. I'm not a mechanic, so cannot do it myself to save the money. If the same problem will occur down the road due it it being the same type of motor, I'd just as soon sell the car to someone who can do the work themselves and give the car a better home. If anyone is interested in it please feel free to let me know.

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  3. #2
    Lithorian's Avatar
    Lithorian is offline Cadillac Owners Enthusiast
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    Re: HT 4100 4.1 motor problems - giving up

    do the 4.5 upgrade....

  4. #3
    Edahall's Avatar
    Edahall is offline Cadillac Owners Enthusiast
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    Re: HT 4100 4.1 motor problems - giving up

    This is a RWD car so a 4.5 upgrade is not one of your choices. You need a RWD block such as a Chevy/Oldsmobile 350 or Cadillac 368. If you're going to keep the same transmission, you'll have to make sure that your transmission will mate up to the new engine. Another possibility is to put in a Cadillac 472/500 fitted to a TH-400 or 4L80E transmission.

    Unless you really like this car, it probably won't be worth financially to do the conversion. You would be better of to find a clean 1991 Cadillac Broughham that already has a 350 motor in it.

  5. #4
    Korky519 is offline Cadillac Owners Member
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    Re: HT 4100 4.1 motor problems - giving up

    Hmm. The shop who I called about replacing the engine had said they'd go with the 4.5, and they knew it was RWD. That makes me not have much faith in their work, if the 4.5 can't even go into this car! Argh. I would love to have a 350 in it but realize it's more work than I could pay for. I think I will follow your advice and start fresh with another year. Thank you. I'll put this car into the papers right away and see what happens. The rust is mostly at the bottom of the doors and can be replaced, so maybe someone will be interested since it has a moonroof, etc. I'm definitely going to look for another one with a moonroof.

  6. #5
    Edahall's Avatar
    Edahall is offline Cadillac Owners Enthusiast
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    Re: HT 4100 4.1 motor problems - giving up

    Yes, you asked your question at the right place.

    Unlike the 4.1 which had a FWD and RWD block, the 4.5 block only came in FWD configuration so I don't know how they thought that they were going to make this engine work.

    If you like your body style, 1980 with the 368 was a good year. Also the last couple of years that had a 350 TBI and 4L60E was good as well. However, finding one with a moonroof won't be easy. That was a rare option.

  7. #6
    Korky519 is offline Cadillac Owners Member
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    Re: HT 4100 4.1 motor problems - giving up

    I'm glad I checked here first. Thank you! I am looking for another car.

  8. #7
    cadillac_al is offline Cadillac Owners Connoisseur
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    Re: HT 4100 4.1 motor problems - giving up

    I think an Olds 307/350 swap would be the cheapest way out for whoever gets the car. A Chev 305/700r4 would be a worthwhile swap too. I hope somebody fixes the car because I love a Caddy with a moonroof.

  9. #8
    Lithorian's Avatar
    Lithorian is offline Cadillac Owners Enthusiast
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    Re: HT 4100 4.1 motor problems - giving up

    oops didnt realize it was rwd

  10. #9
    Tommy Deville's Avatar
    Tommy Deville is offline Cadillac Owners Enthusiast
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    Re: HT 4100 4.1 motor problems - giving up

    Those 368's only came with a 3 speed tranny, gas mileage is terrible. Wonder how they so with a 4 speed

  11. #10
    Edahall's Avatar
    Edahall is offline Cadillac Owners Enthusiast
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    Re: HT 4100 4.1 motor problems - giving up

    Quote Originally Posted by Tommy Deville View Post
    Those 368's only came with a 3 speed tranny, gas mileage is terrible. Wonder how they so with a 4 speed
    Huh??? I had a friend with one of these cars and he would get in the lower 20's on the freeway.

  12. #11
    mannerpanner's Avatar
    mannerpanner is offline Cadillac Owners Member
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    Re: HT 4100 4.1 motor problems - giving up

    If you drop in a 307 you'll never have a problem again. Worthwhile swap.

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