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Technical SBC Tapping/Ticking noise

Discussion in 'The Hokey Ass Message Board' started by 49ChevTruck, May 6, 2016.

  1. Got a 350 sbc in a 48 chevy and i've noticed over the past week or two i've got a tapping/ticking noise when i lift off the throttle when driving it. I don't get it at idle.....

    Any idea's what it might be?
     
  2. Dooley
    Joined: May 29, 2002
    Posts: 2,693

    Dooley
    Member
    from Buffalo NY

    I've had a few sbc noises
    dip stick in backwards hitting crank
    Rockers hitting valve cover
    pushrod that lost the end piece at only did it as i puilled to a stop light
    fan belt deteriorated and flapping against pulleys

    Good luck
    i figure to get in before the "sounds like a wiped out cam to me" guys lol

    Best best is to have a buddy rev the engine while you look at listen on both sides
     
    hipster likes this.
  3. Haha thank you dooley, I read an old thread on here and I noticed all the guys saying "you've wiped out a cam" guys
     
  4. All the time i'm accelerating I don't get any noise just when I back off the throttle
     

  5. Blues4U
    Joined: Oct 1, 2015
    Posts: 5,273

    Blues4U
    Member
    from So Cal

    Sounds like it's coming from the engine, not the driveline? As the load shifts from driving to driven u-joints and diffs that are about to go can start to make odd noises like that. If it's an automatic, maybe the flex plate.
     
  6. Yes it sounds like it's from the engine, don't think it's a driveline issue I'll check it out tomorrow.
     
  7. oldrelics
    Joined: Apr 7, 2008
    Posts: 1,727

    oldrelics
    Member
    from Calgary

    I have similar elusive tick, drives me nuts, I've been all over the top end, no finding it.
    My dad had one as well, turned out on his it was a bent connecting rod, and don't ask me how that would make a ticking noise.....
     
  8. tfeverfred
    Joined: Nov 11, 2006
    Posts: 15,792

    tfeverfred
    Member

    You broke it. Now, decide how badly.:(
     
  9. Tim
    Joined: Mar 2, 2001
    Posts: 12,031

    Tim
    Member
    from KCMO

    Make sure there's oil in it. Seriously
     
  10. What he said ^^^^^^
     
  11. I had a ticking noise in my 283 looked at all the normal things lifter, rocker arms, cam could not find any thing. The noise would get louder under acceleration and quite off when I let off, After a couple of days we pulled the engine found a broke rod bearing not a turned but broke, the number 5 top bearing was broke about a inch from the tap. The motor had been in and ran for about two and half years just started one after noon while out driving. Good luck man
     
  12. blowby
    Joined: Dec 27, 2012
    Posts: 7,258

    blowby
    Member
    from Nicasio Ca

  13. If it only does it during deceleration and you've eliminated the more obvious stuff...

    Check the engine and transmission mounts and check any exhaust or linkages that run close to the body or chassis. Look for any witness marks like like shiny metal where there should be paint or rust.

    Check for loose converter bolts or cracked flex-plate.

    Try running it with the fan, alternator and/or P/S pump belt removed. Check for cracked or broken fan blades or a loose fan. Check for excessive end play and side play in the water pump.
     
  14. canning
    Joined: Jan 22, 2012
    Posts: 70

    canning
    Member

    Stretched/worn timing chain?
     
  15. Broken spring in fuel pump lever.
     
  16. stimpy
    Joined: Apr 16, 2006
    Posts: 3,547

    stimpy

    had a broken exhaust manifold do the same thing , the lack of engine noise at idle made it more noticable plus the motor rolling over helped push it together sealing the crack .
     
  17. I'll check through it today and see if I can notice anything, I'll give you guys an update later on tonight. Thank everyone
     
  18. mgtstumpy
    Joined: Jul 20, 2006
    Posts: 8,625

    mgtstumpy
    Member

    I've had a sticky lifter since the engine was rebuilt and I've never bothered to follow it up or replace it. I just live with it now.
     
  19. pnevells
    Joined: Sep 5, 2008
    Posts: 454

    pnevells
    Member

    Left a wrench in the valley, don't laugh, it happens....
     
  20. R Pope
    Joined: Jan 23, 2006
    Posts: 3,309

    R Pope
    Member

    "Left a wrench in the valley"....haha. Been there, done that!
    Check the fuel pump first, then the flex plate. Being a SBC, it could be a cracked piston......
     
  21. lippy
    Joined: Sep 27, 2006
    Posts: 5,364

    lippy
    Member
    from Ks

    Hood ornament loose?:D
     
  22. Lippy thats a good point i've actually got a bolt missing out the hood ornament!
     
  23. Frank Carey
    Joined: Oct 15, 2009
    Posts: 520

    Frank Carey
    Member

    My ticking was a cracked flex plate. Hope that's not your problem.
     
  24. Well I took the car out about an hour ago and I only really get it when I get up to about 50mph and i'm backing off the throttle....so not really sure what it could be still. I'm going to try the hood ornament bolt see if that makes a difference but i'm sure it's coming from the engine bay.
     
  25. Pull the fuel pump and see that f the fulcrum spring is broken or severely fatigued.
     
  26. My SBC in my '36 Ford had a soft rapid ticking only when decelerating. Drove me batty for 4 years. Finally pulled the engine and had it rebuilt professionally.
    Reinstalled it and drove it for one more year, still had the same clatter when I lifted.
    Pulled the fuel pump one balmy Sunday morning and the bright sunlight picked up a shiny reflection inside the hole in the block.
    There it was, HALF OF THE FULCRUM spring laying in the hole, broken off, but the other half now cocked at an angle riding on the fuel pump.
    I cant figure out how it ran so well with only half a crooked spring working the fulcrum arm.
    Threw on the new fuel pump, noise gone.
     
  27. Don's Hot Rods
    Joined: Oct 7, 2005
    Posts: 8,319

    Don's Hot Rods
    Member
    from florida

    If it does it mainly on deacceleration, that leads me to believe it is connecting rod/bearing/piston related. When you are accelerating, or holding a steady speed, there is a load on them, taking up some of the slop. But when you let off the gas, the piston and rod assembly are kind of floating or put under a different kind of load.

    Guy who has a shop next to our shop has a pickup with a sbc in it and he asked us to listen to it one day. It was ok revving it up, but when he let off the gas, you could hear it sort of knocking. I said piston was my guess. A week ago, he stopped by and told me they tore the motor down and found one bearing and the wrist pin on that piston had slop in them.

    Also, check your convertor to flexplate bolts. Weird noises come from them being loose.

    Don
     

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