Engine seems to be knocking
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Northstar Engines and System Technical Discussion Discussion, Engine seems to be knocking in Cadillac Engine Technical Discussion; My engine recently started to knock. The car ran just fine until it seems cold weather has arrrived. It does ...
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    Trench's Avatar
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    Engine seems to be knocking

    My engine recently started to knock.

    The car ran just fine until it seems cold weather has arrrived. It does lighten up a little as time goes on, but still stays with me even after the engine has been fully warmed up. I have read up on cleaning with the GM TEC stuff to solve a "cold knock" but I don't think that will apply because it is always there, cold or hot. It does change with throttle. Much worse under hard acceleration. During a slow acceleration it is hardly noticable. Any ideas?



    Dustin

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    Ranger's Avatar
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    Re: Engine seems to be knocking

    Have you tried some good ole WOT?

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    Re: Engine seems to be knocking

    Quote Originally Posted by Ranger
    Have you tried some good ole WOT?

    Yeah, I have. On several occations. Took it on the highway and rode it hard in 2nd gear. Didn't really seem to help anything.

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    Re: Engine seems to be knocking

    knocking, ticking, or pinging?

    Knocking is not good, obviously. Get a stethoscope for cars (~$10) and with the engine on, try to find it if is coming from the lower end (ramps) or from above (Camshaft). Usually the ticking from the top is normal. You don't hear it while driving with the windows up, do you?

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    Re: Engine seems to be knocking

    If the car is running with the hood up and you are standing there when some one gooses the engine, do you jump back to get away from the flying parts or does it sound like the works are politely conversing with each other? A rod knock will be a very sharp rap that gets much worse with RPM and will really sound off on the over run. It will be obvious that something is trying to break. Most other noises that get gradually louder with RPM and don't change on the over run are probably valve related. The use of a stethoscope as suggested earlier is a very good idea.

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    Re: Engine seems to be knocking

    The ticking noise, I imagine from the injectors, is only really noticable with the engine cover off.

    The engine sound just fine when idling and when be revved up. The knocking seems to come into play under load. Also, the knocking has seem to let up some in the past few days. I will see if I can borrow one of the stethoscopes from work and try to locate it.

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    Re: Engine seems to be knocking

    my engine knock but i cant hear unless im outside of car and lookin for the sound

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    Re: Engine seems to be knocking

    Screw additives, ever tried using Premium Fuel? I always run 93.

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    Re: Engine seems to be knocking

    Quote Originally Posted by auroradude
    Screw additives, ever tried using Premium Fuel? I always run 93.

    Screw additives? Blind ignorance is too common these days, almost disgusting. Grow a brain before you post. Also, any response to my comment will be ignored, being as I'm sure I will get one, and I don't wish to start a battle.

    Now, are most additives junk, I'm sure most would agree yes.

    Are all additives junk? No.

    Not to mention, where did that come from? I don't see any mention of additives on this thread. Along with the fact 93 Octane is a waste of money on my year car. The engine is tuned for regular gas. Only benefit of high grade fuel may be detergents.

    Honestly...How would high octane fuel help anything in this thread? Our engines are not detonating or pinging.

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    mcowden is offline Cadillac Owners Connoisseur
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    Re: Engine seems to be knocking

    Quote Originally Posted by Trench
    My engine recently started to knock.

    The car ran just fine until it seems cold weather has arrrived. It does lighten up a little as time goes on, but still stays with me even after the engine has been fully warmed up. I have read up on cleaning with the GM TEC stuff to solve a "cold knock" but I don't think that will apply because it is always there, cold or hot. It does change with throttle. Much worse under hard acceleration. During a slow acceleration it is hardly noticable. Any ideas?



    Dustin
    Hey Dustin - I have noticed a sound before on my car that might be what you're describing. It sounds almost like there's a tiny diesel engine inside your Northstar. On my car at least, it goes away when the engine heats up. I've also tried lots of WOT (still do it just to be sure) and it never goes away. After much discussion with a guru who used to frequent this forum, I've chalked it up to normal valvetrain clatter. He had suggested using Rotella 15W-40 motor oil for one change cycle to see if the slightly heavier oil would quiet the clatter. I would only do that during the summer months, but I have never tried it. I'm convinced it's nothing to worry about, at least the sound I'm hearing from the front of my car when it's cold. Does yours sound kind of like a quiet diesel sound?
    Mike

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    Re: Engine seems to be knocking

    mines has a uiet knock but only noticiable outside of car i was gonna try some slick 50 for heat and friction.....? wat u think the northstar engine does get really hot

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    Re: Engine seems to be knocking

    My 93 Eldo had a light knock when I first got it and I put a half can of sea foam in the oil and put the other half can down the intake then let the car sit shut down for 5 minutes and started it up and drove it till it quit smoking and the sound went away.It still has a cam/valvetrain tick but that sound has never changed and I think its normal. I know some additives are bogus but sea foam has worked for me many times and I use it in anything I have with an engine FWIW

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    Re: Engine seems to be knocking

    Quote Originally Posted by keep it fresh
    mines has a uiet knock but only noticiable outside of car i was gonna try some slick 50 for heat and friction.....? wat u think the northstar engine does get really hot
    Save your money for something useful. Slick50 is snake oil.

  15. #14
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    Re: Engine seems to be knocking

    How many miles on it? I can't hear it obviously, but the symptoms point to rod bearings. Loads put a strain on the crank, heat and expansion diminish the sound by reducing clearance but it won't go away. I've heard that Rotella helps some.

    That's my $.02. I hope I'm wrong.

  16. #15
    mcowden is offline Cadillac Owners Connoisseur
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    Re: Engine seems to be knocking

    Quote Originally Posted by keep it fresh
    mines has a uiet knock but only noticiable outside of car i was gonna try some slick 50 for heat and friction.....? wat u think the northstar engine does get really hot
    Slick 50 is useless. It won't help friction or temperature. It only helps the finances of the Slick 50 company, not your car.
    Mike

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