4.1 Motor? Rattles/Engine Pinging?
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HT4100 4.1, 4.5, 4.9 Discussion, 4.1 Motor? Rattles/Engine Pinging? in Cadillac Engine Technical Discussion; I don't know what's the deal with my 87, it runs perfectly fine and it starts up without any hesitation. ...
  1. #1
    JoJo_Brand_Star is offline Cadillac Owners Member
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    4.1 Motor? Rattles/Engine Pinging?

    I don't know what's the deal with my 87, it runs perfectly fine and it starts up without any hesitation. I figure the noise may be because of a bad cat, but it only make a rattling noise when i accelerate.
    Now question is, what could that possibly be?
    Someone told me it could because of bad gas, i'm not to sure what the case may be.
    But if it is bad gas, where would be the best place to get gas from, I understand it uses regular unleaded fuel.

    So please, if anybody know what could be the issue with the rattling,i need help. lol

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    Ranger's Avatar
    Ranger is offline Cadillac Owners Member
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    Re: 4.1 Motor? Rattles/Engine Pinging?

    I am not sure if the 4.1 has a spark knock detector or not. The 4.9 doesn't and thus needs premium. What does your owners manual call for and what are you running?

  4. #3
    JoJo_Brand_Star is offline Cadillac Owners Member
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    Re: 4.1 Motor? Rattles/Engine Pinging?

    Spark knock detector? i have my manual, but what is that?
    I am slowly learning about cars, so please educate me. haha

  5. #4
    Ranger's Avatar
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    Re: 4.1 Motor? Rattles/Engine Pinging?

    The spark knock detector "listens" to the engine and if it detects a spark knock (detonation) or pinging it will retard the timing to prevent it. That is why the pre 2000 Northstars can run 87 even though the owners manual calls for premium.

  6. #5
    JoJo_Brand_Star is offline Cadillac Owners Member
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    Re: 4.1 Motor? Rattles/Engine Pinging?

    Okay.....
    So since my maunal says regular unleaded, what grade should i use?
    I know some that used used regular gas, which there suppose to used premium fuel.
    But they don't any problems, because that's the only thing wrong with my poor little caddy is that annoying noise when i accelerate.

  7. #6
    Ranger's Avatar
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    Re: 4.1 Motor? Rattles/Engine Pinging?

    Well, if it says regular, you should be able to use regular. Have you messed with the timing?

  8. #7
    JoJo_Brand_Star is offline Cadillac Owners Member
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    Re: 4.1 Motor? Rattles/Engine Pinging?

    Timing? from what i understand a timing chain doesn't ever go bad or need to be replaced. So what possibly would i need to do my timing?

  9. #8
    Ranger's Avatar
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    Re: 4.1 Motor? Rattles/Engine Pinging?

    That is VALVE timing. IGNITION timing is adjusted by loosening the lock down bolt under the distributor and twisting the distributor one way or the other to retard or advance the timing. Sounds like you didn't touch it.

  10. #9
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    Re: 4.1 Motor? Rattles/Engine Pinging?

    Try a tank-full of premium and see if it goes away. Try to listen for where the sound is coming from.

  11. #10
    carnut is offline Cadillac Owners Master
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    Re: 4.1 Motor? Rattles/Engine Pinging?

    Nobody can diagnose a noise thru the internet without a recording. A rattle noise on accelleration should be demonstrated to a car savvy friend. Not knowing about cars gives you the disadvantage of not being able to describe it fully. Go to a local muffler shop and have them drive it with you. Possibly a broken cat converter to a inoperative EGR valve to distributor timing to a loose strut. AND PUT YEAR AND TYPE OF CAR IN WITH YOUR SIGNATURE PLEASE!! 87 what??

  12. #11
    JoJo_Brand_Star is offline Cadillac Owners Member
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    Re: 4.1 Motor? Rattles/Engine Pinging?

    It's a 1987 Cadillac Sedan Deville equipped with the HT4100 Motor
    with 81,000 miles on it.

  13. #12
    carnut is offline Cadillac Owners Master
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    Re: 4.1 Motor? Rattles/Engine Pinging?

    Put that info in your signature please.

  14. #13
    JoJo_Brand_Star is offline Cadillac Owners Member
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    Re: 4.1 Motor? Rattles/Engine Pinging?

    It's visible now, for everyone to see.

  15. #14
    Submariner409's Avatar
    Submariner409 is offline If it won't run, slap in a big stereo
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    Re: 4.1 Motor? Rattles/Engine Pinging?

    This identical question/observation (bad gas/rattling) has been posted somewhere else and has received an answer. (Your "best kind of motor oil" thread.....)

  16. #15
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    HUF
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    Re: 4.1 Motor? Rattles/Engine Pinging?

    Quote Originally Posted by JoJo_Brand_Star View Post
    I don't know what's the deal with my 87, it runs perfectly fine and it starts up without any hesitation. I figure the noise may be because of a bad cat, but it only make a rattling noise when i accelerate.
    Now question is, what could that possibly be?
    Someone told me it could because of bad gas, i'm not to sure what the case may be.
    But if it is bad gas, where would be the best place to get gas from, I understand it uses regular unleaded fuel.

    So please, if anybody know what could be the issue with the rattling,i need help. lol
    Had exactly the same problem for years. It was exhaust pipe touching a bracket somewhere under the car. Could not locate the source of the noise until I put it on a hoist and asked a friend to power-brake it gently. I had seen the source of the noise immediately. Bent a little bit the bracket off the pipe and that was it.

    When you accelerate the engine and the whole exhaust system attached to the latter move a little bit back. That a little bit may be just enough to hit the body of the car and make that terrible rattling noise.

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