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Technical small block knocking sound on cold start, balancer?

Discussion in 'The Hokey Ass Message Board' started by error404, Sep 1, 2019.

  1. porknbeaner
    Joined: Sep 12, 2003
    Posts: 40,994

    porknbeaner
    Member

    Grab a screw driver, stick the plastic end on our ear and use it like a stethoscope and find out where the noise is coming from. I would not guess that it is the harmonic balancer, they do not heat up and swell. It is most likely dry bearings at start up. That is a common problem with one that is a weekender car.
     
  2. error404
    Joined: Dec 11, 2012
    Posts: 103

    error404
    Member
    from CA

    I'll pull the belts next weekend on a cold start. :) Don't want to do that during the week, as I'm driving the truck to work to get familiar with it.


    I've been driving the truck every day for a few weeks now, since the day I drove it home. That's how I like to find things that need attention, just drive it as much as I can :) My 46 Willys Jeep I even drove across the country once, from California to North Carolina and back :D
     
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  3. 427 sleeper
    Joined: Mar 8, 2017
    Posts: 545

    427 sleeper
    ALLIANCE MEMBER

    Food for thought, when you get the belts off the front, check ALL the chrome aftermarket brackets and accessories. It has been my experience that they can and usually do crack in the damnedest places, due to hydrogen embrittlement, making some of the strangest noises you've ever heard. Again, just something to consider.
     
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  4. gimpyshotrods
    Joined: May 20, 2009
    Posts: 16,140

    gimpyshotrods
    Member

    What's a balancer?
     
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  5. 2OLD2FAST
    Joined: Feb 3, 2010
    Posts: 1,620

    2OLD2FAST
    Member
    from illinois

    I don't pretend to understand all the nuances of engine balancing , but if a damper is not a balancer , then why does an externally balanced engine require a counterweighted damper while an internally balanced engine requires a neutral balanced damper ( or is it dampener) ? It would seem if one has to add or subtract weight from a damper to balance the rotating assembly that the damper is indeed a balancer of sorts .....
    When you're old and can't sleep , things like this run through your mind ......
     
  6. F-ONE
    Joined: Mar 27, 2008
    Posts: 1,859

    F-ONE
    Member
    from Alabama

    Sounds like fingernails tapping a glass table??
    Is that the sound?
    Gee Whiz, that could be anything.
     
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  7. brigrat
    Joined: Nov 9, 2007
    Posts: 4,780

    brigrat
    ALLIANCE MEMBER
    from Wa.St.

    Had a friend bring in a '32 Ford Roadster with a knocking at idle, I told him to shut it off and I grabbed a small crow bar, put it between harmonic and block and was able to move the crank back and forth a good 1/8" of an inch. Thrust bearings on crank and crank face surface were badly worn. First SBC I had seen that way...............................
     
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  8. Truck64
    Joined: Oct 18, 2015
    Posts: 3,422

    Truck64
    Member
    from Ioway

    I was always told generally engine noises when cold are one thing, though noises that don't go away or continue when hot are bad stuff, and indicate serious problems. I think that's probably mostly true.
     
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  9. Truck64
    Joined: Oct 18, 2015
    Posts: 3,422

    Truck64
    Member
    from Ioway

    Crankshaft balancers absorb torsional vibration, the crank can twist a couple degrees back and forth. The heavy outer weight sandwiched with rubber leads and lags the crank due to inertia and smooths out the power pulses. Crankshafts have a resonance point at certain RPM, and a further resonance at certain harmonics of that frequency. I think engineers try to design the resonance frequency out or minimize it, but there will be a point where it could be a problem.
     
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  10. olscrounger
    Joined: Feb 23, 2008
    Posts: 3,479

    olscrounger
    ALLIANCE MEMBER

    Had two OT GMC pickups that had a knock when cold for about 3-4 minutes. Drove em 100K miles-never changed. Had a ZZ motor in a 40--same deal-still running strong-suspect piston slap. Wife's 55 developed a knock also--it was constant-chased it for a long time--ran fine--it was the fuel pump and rod.
     
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  11. 2OLD2FAST
    Joined: Feb 3, 2010
    Posts: 1,620

    2OLD2FAST
    Member
    from illinois

    That's wonderful but it doesn't answer the ? as to why some are neutral balanced and some are counter weighted ...
     
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  12. error404
    Joined: Dec 11, 2012
    Posts: 103

    error404
    Member
    from CA

    I did put my hand on the mechanical fuel pump, and it does seem to feel the noise through it more than the motor itself, but that might just be because it's hanging off the motor. Can't really touch the pulleys much while running though, haha!

    This weekend if I'm not working, I'll fire the motor up without the belts, and also inspect the pulleys and the chrome junk on the front of the motor.

    Thanks for all the continued replies :)
     
  13. X-cpe
    Joined: Mar 9, 2018
    Posts: 648

    X-cpe

    That is why they are called torsional vibration dampers sometimes.

    Where the name harmonic balancer comes from. I was taught in the practical world the names were interchangeable, if not always technically correct.

    I think you mean internally vs. externally balanced. I believe some engines are externally balanced because because the engineers couldn't find a practical, inexpensive way to get enough weight on the crankshaft where it was needed and still fit the crankshaft in the crankcase, so they added the weight to the flywheel and balancer. ( examples: SBC, 265-350 internal, 400 external; BBC, 396 & 427 internal; 454 external.
     
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  14. MeanGene427
    Joined: Dec 15, 2010
    Posts: 1,337

    MeanGene427
    Member
    from Napa

    Seriously? Nah, a Chebbie would never have an engine noise
     
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  15. 2OLD2FAST
    Joined: Feb 3, 2010
    Posts: 1,620

    2OLD2FAST
    Member
    from illinois

    So , if the "damper" enhances or aides the balance of the crankshaft , it would indeed be a balancer , no ??
     
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  16. bonzo-1
    Joined: Oct 13, 2010
    Posts: 325

    bonzo-1
    Member

    Put a dowel on the timing chain cover and listen if the sound is coming from there. Maybe loose timing chain.
     
  17. Los_Control
    Joined: Oct 7, 2016
    Posts: 589

    Los_Control
    Member
    from TX

    I paid $1k for a 1987 ford van, had a newer crate engine in and I drove it from WA to NM and then drove it for 12 years fully loaded as a work van.
    It always made a clunking noise when first started in the morning.

    I cared about this van, I took good care of it, change the oil etc... It always knocked when starting.
    I drove it 12 years this way, sold it wit a good running engine and bad tr

    Now I have a ot dodge, does the same thing, I am not worried about it.
    I would prefer it not make a noise when starting, only when sitting over night.
    We are talking to do engine mods to stop this.
    Sometimes we need to pick our battles. If my hot rod made noises, I may fix it.
     
  18. Boneyard51
    Joined: Dec 10, 2017
    Posts: 2,435

    Boneyard51
    Member

    In roughly the nineties, we had a new OT Chevytruck with V-8 that had a cold start knock. Took it back for warranty..... they replaced the engine, but never gave us the reason for the knock! But apparently General Motors knew what is was...... because we got a new engine!





    Bones
     
  19. 56sedandelivery
    Joined: Nov 21, 2006
    Posts: 5,683

    56sedandelivery
    ALLIANCE MEMBER

    I was going to ask if there was a retaining bolt on the dampener, or if it was tight. But, that sound does't really sound like a dampener issue; sounds more like one of the "accessories" or accessory bracket's the culprit. Could it even be the electric fan touching something? Good luck with your "snipe hunt". I am Butch/56sedandelivery.
     
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  20. Greg Rogers
    Joined: Oct 11, 2016
    Posts: 25

    Greg Rogers
    Member

     
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  21. gimpyshotrods
    Joined: May 20, 2009
    Posts: 16,140

    gimpyshotrods
    Member

    The harmonic damper does not balance anything, whether or not it has an asymmetrical body. It is simply counterweighted.

    You cannot just shove one on, and call your engine balanced. Balancing is a process.

    The person who balances the rotating assembly is the balancer.
     
  22. Boneyard51
    Joined: Dec 10, 2017
    Posts: 2,435

    Boneyard51
    Member

    Gimpy, i
    Gimpy, it’s all terminology! I’ve heard the thing on the end of the crankshaft called many things!
    I know some words rub folks the wrong way, it has to do with what they were taught! I myself have problems with “ motor “ vs engine. But that has been beat to death here!
    Everyone knows what everyone is talking about when they say... dampener, pulley, harmonic.... whatever! It’s OK!

    But when people talk about suction............ that a whole different can of worms! There is no such thing a suction!!! There is only differences of pressure!





    Bones
     
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  23. 2OLD2FAST
    Joined: Feb 3, 2010
    Posts: 1,620

    2OLD2FAST
    Member
    from illinois

    Oh my !someone really enjoys Thier semantics , don't they .......?
     
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  24. gimpyshotrods
    Joined: May 20, 2009
    Posts: 16,140

    gimpyshotrods
    Member

    It's only called semantics when you're wrong. ;-)
     
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  25. Truck64
    Joined: Oct 18, 2015
    Posts: 3,422

    Truck64
    Member
    from Ioway

    Some of 'em really get into that!
     
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  26. 2OLD2FAST
    Joined: Feb 3, 2010
    Posts: 1,620

    2OLD2FAST
    Member
    from illinois

    You'll have to let us know sometime how it feels to presume you're so infinitely superior ..
     
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  27. error404
    Joined: Dec 11, 2012
    Posts: 103

    error404
    Member
    from CA

    Ok, lets get back on track :-D
     
  28. 19Fordy
    Joined: May 17, 2003
    Posts: 6,384

    19Fordy
    Member

    Could it be the alternator? Sounds external.
     
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  29. 2OLD2FAST
    Joined: Feb 3, 2010
    Posts: 1,620

    2OLD2FAST
    Member
    from illinois

    According to Webster ; One who OR that which balances....
     
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  30. gimpyshotrods
    Joined: May 20, 2009
    Posts: 16,140

    gimpyshotrods
    Member

    Sure, and there is no device on a HAMB friendly engine that which balances, of any kind.
     

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