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What is this sound??

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by K5thatShmobs, Mar 15, 2003.

  1. K5thatShmobs

    K5thatShmobs 1/2 ton status

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    Today it showed up. Under acceleration, I get this "ticking" sound that changes in speed in time with the engine RPM. (e.g. The more pedal, the faster the "ticking" gets.) I sounds like its definitely coming from under the truck, but I have no idea where. I know this is minimal info to diagnose anything, but I was hoping someone may have heard this kind of sound and figured out what it was.
     
  2. Ryan2286

    Ryan2286 Registered Member

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    does it do it only when in gear or will it make the noise in park or neutral as well?
     
  3. jimmyjack

    jimmyjack 1/2 ton status

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    Bad lifter, exhaust leak, or a broken flex plate. A bad lifter isn't treally a ticking noise. An exhaust leak will show some soot if your lucky. I'd be willing to bet on a flex plate tho. All of my tranny mounting bolts fell out and the tranny was hanging. Whenever I'd apply the gas it would go away. It really had me stumped til I happened to notice 1 bolt missing then 2 then 3.......I'd pull the inspection cover and try to get a peek in there. Good Luck
     
  4. 8_YOUR_H2

    8_YOUR_H2 1/2 ton status

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    I had a leaky exhaust manifold gasket that made the "tick.....tick" noise....
     
  5. tecton

    tecton 1/2 ton status

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    i stand behind my pipes and get black rings on my pants

    soot?
     
  6. nevercomplete

    nevercomplete 1/2 ton status

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    My truck does the same, it is an exhaust leak on mine.

    Jon
     
  7. muddysub

    muddysub 1 ton suburban status Staff Member Moderator GMOTM Winner

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    i've had 2 flexplates go and they start out as a tick then its a rattle after a while. if it gets worse i'd be willing to bet it's the flexplate.
     
  8. nevercomplete

    nevercomplete 1/2 ton status

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    I'm not too good with noises /forums/images/graemlins/1zhelp.gif

    Jon
     
  9. BigRed89

    BigRed89 1/2 ton status

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    Take a look at the flexplate. I had a similar problem on my '89 Sub, as well as on my friend's '91 Sub.
     
  10. doctor4x4

    doctor4x4 1/2 ton status

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    sounds like the notorius muffler bearing the only way to fix it is ya gotta put beaver oil in your gas when ya fill up /forums/images/graemlins/grin.gif
    no seriously i vote for the exhaust leak
     
  11. Blazinaire

    Blazinaire 1/2 ton status

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    Its really hard to say... Our suburban was making that noise untill a couple of days ago and it turned out to be a cracked flex plate (which damaged the torque converter which contaminated the tranny which completely smoked the clutches... which left our sub stuck on pepper street near stanley motors there in san luis so feel free to go make sure that no one has been messing with it /forums/images/graemlins/crazy.gif.) What I'm getting at is that pulling the inspection cover off the tranny doesn't take long, but avoiding it can cause some catastrophic damage ($$$) if it is the flex plate and you catch it in time, autozone has new ones for $35 although it is a pain to change it, it's a lot cheaper than changing the whole tranny with it /forums/images/graemlins/frown.gif.
     
  12. K5thatShmobs

    K5thatShmobs 1/2 ton status

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    Im trying to figure out what might cause a bad flex plate... I just put in the new tranny with a new flex plate a couple months ago. And just to make absolutely sure... a flex plate is the same thing as what most call a flywheel, correct?

    Okay, so If I do pull the inspection cover, what am I looking for? Cracks? Im thinking that those would be in the middle of the flex plate, and it seems to me that you wouldnt be able to see the middle just by pulling that one cover below the TC.

    Oh and by the way, the sound just started today... I hope it hasnt been too long.

    As for the exhaust, it was done right before my eyes by a very good tech about a month ago, and the noise doesnt sound too much like exhaust.
     
  13. jimmyjack

    jimmyjack 1/2 ton status

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    Yes look for cracks radiating out from the center out to the edges, espescially near the big holes that are in the flex plate. I wish I had my digi camera still. The whole center of mine stayed on the truck and rest fell off when I pulled off of the crank. Looked like a big donut
     
  14. KShortell

    KShortell Registered Member

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    "Under accelaration"-- makes me initially think of an exhaust manifold gasket. I had to replace mine a couple of times in a couple of years-- bolts kept loosening up on me- even with thread-locker. I think I'm going to see if I can get Stage 8 bolts that work with manifolds if I ever have to replace 'em again...

    I've not had a flexplate crack on me, but I did have one warp a bit, causing a driveline vibration. A warped one won't make a noise, although I bet a cracked one does! For more on mine and how I replaced it, see here: '86 350 Flexplate Replacement

    Good luck! I know that sounds can be really annoying. It tooke me a long time to pinpoint my problem. I fixed everything but the real problem first! /forums/images/graemlins/blush.gif


    Kevin
    /forums/images/graemlins/burb.gif
     
  15. Bob Hope

    Bob Hope Registered Member

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    take the ace of spades out of your spokes! /forums/images/graemlins/rotfl.gif
     
  16. tomseviltwin

    tomseviltwin 1/2 ton status

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    With the engine at idle, open the hood and look at your accesory belts. If you notice they "bounce" a little in harmony with the ticking sound, your flexplate is cracked and the bolts are hitting the inspection cover, as this condition progresses it will sound like a rod knock and you'll think your just about to lose an engine in Barstow Hell on a roadtrip to Disneyland. /forums/images/graemlins/eek.gif /forums/images/graemlins/eek.gif /forums/images/graemlins/eek.gif /forums/images/graemlins/rolleyes.gif

    Don't ask me how I know /forums/images/graemlins/rotfl.gif /forums/images/graemlins/rotfl.gif /forums/images/graemlins/rotfl.gif
     
  17. K5thatShmobs

    K5thatShmobs 1/2 ton status

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    Alright well I just popped the inpection cover and the flywheel looks fine. I had a buddy crank the engine a few times and I didnt see any cracks or anything. I then went around all the bolts on the bellhousing to make sure they were all tight. I have a 700R4 with the support strut that goes from the t-case to the bottom right bolt on the bell housing, and that bolt head was broken off... again! A grade 8 bolt also. I dont know if the lack of support in that area has anything to do with my ticking sound, but it keeps breaking. This is my second strut, too. I broke my first one.

    Im in a real bind this time though... the entire bolt minus the head is still threaded into the block. I dont know how Im going to get it out. I cant really use an easy-out drill bit or something because its too cramped of a space to get a drill in there. I really really dont want to drop the tranny again...

    Does anyone know if the threads of the bolts holding on the bell housing will show up on the other side, or are they threaded directly into the engine block? For this particular bolt I would have to remove the starter to see. That might enable me to get it out if I could get a grip on the threads coming out the back.
     
  18. bad andy

    bad andy 1/2 ton status

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    you might need to have your carb rebuilt, mine ticks when its cold under acceleration
     
  19. vince13

    vince13 1/2 ton status

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    if the noise is in sync with the rpm it could be a loose rocker ticking away. do a valve lash adjustment and see if that solves the problem
     
  20. K5thatShmobs

    K5thatShmobs 1/2 ton status

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    Alright I put the truck up on stands and had a buddy apply some gas while I was searching around on the underside.. It turns out its the CV shaft on the rear driveline! The "ticking" when you get closer to its source sounds more like a "knocking". Has anyone had a knocking CV shaft before?
     

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