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OK GUYS- bad metallic rattle!!!*******UPDATE*******

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by Can Can, Aug 22, 2001.

  1. Can Can

    Can Can Pusher Man Staff Member Super Moderator

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    A really ugly noise started coming from under the 84 today. If I'm travelling at 35mph, and start to accelerate, I get a rattly, tinny really wierd sound coming from under the truck. When I let off the gas, it goes away. It's not engine pinging- it almost sounds like an exhaust pipe banging but it's not because it's accompanied by a whirring sound. There's no vibration along with the sound.

    I took the truck down to the shop and crawled underneath and spent a good half hour twisting and tugging and couldn't find anything loose<img src="http://coloradok5.com/forums/images/icons/frown.gif">.

    I brought the truck home and drove down the street with my wife on the sidewalk. She's almost positive that the sound is coming from the rear of the truck, which leads me to believe it's either a rear u-joint or the rear diff.

    Does anyone have ANY ideas?????? I leave for vacation on Sunday and have to have this figured out before the weekend!!!!!! HELP!!!!!!!



    <font color=red>PHOTO ALBUM-</font color=red> &lt;a target="_blank" href=http://albums.photopoint.com/j/AlbumList?u=1289798&gt;http://albums.photopoint.com/j/AlbumList?u=1289798&lt;/a&gt;.......<font color=blue>TRUCK &amp; HIKING PICS</font color=blue>
     
  2. Pugsley

    Pugsley 1/2 ton status

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    Re: OK GUYS- bad metallic rattle!!!

    Sounds like it might be a U-joint fixing to take the big dirt nap - lord knows what else it could be.

    Dos mas Tecates!!!
    <a target="_blank" href=http://pugsley.alloffroad.com>pugsley.alloffroad.com</a>
     
  3. Can Can

    Can Can Pusher Man Staff Member Super Moderator

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    Re: OK GUYS- bad metallic rattle!!!

    That's kinda what I'm hoping, except there's absolutely no play in either rear joint. How does a diff sound when it starts to let go?



    <font color=red>PHOTO ALBUM-</font color=red> <a target="_blank" href=http://albums.photopoint.com/j/AlbumList?u=1289798>http://albums.photopoint.com/j/AlbumList?u=1289798</a>.......<font color=blue>TRUCK & HIKING PICS</font color=blue>
     
  4. anatomiczero

    anatomiczero 1/2 ton status

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    Re: OK GUYS- bad metallic rattle!!!

    When my u joints were going bad it made a whistling noise under load, it also vibrated (felt from floor boards) So my dad took it to Les Schwab (it's still my dad's jimmy for now) and the guy test drove it then said there was no play in the drive shaft. He brought it home, went under it and there was play, took the u joint out and all of the needle bearings in 1 of them were completely gone. So we replaced the joints with some lifetime gurantee's from car quest, they went out twice (within a couple of months), then we got some spicers from napa and they're fine to this day (about a year)

    Black 1980 GMC Jimmy
    350-TH350-NP205
    Dual glasspacks
     
  5. Pugsley

    Pugsley 1/2 ton status

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    Re: OK GUYS- bad metallic rattle!!!

    The only diff I've ever had let go just made a sharp crack, and that was it - The last U-joint I lost had absolutely zero play in it the day before it broke - and it made some similar noises for a few miles before it let loose.

    Dos mas Tecates!!!
    <a target="_blank" href=http://pugsley.alloffroad.com>pugsley.alloffroad.com</a>
     
  6. Can Can

    Can Can Pusher Man Staff Member Super Moderator

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    Re: OK GUYS- bad metallic rattle!!!

    OK............OK.............now I feel better. I guess I'll swap in a new u-joint tomorrow and see if that fixes the problem. It makes sense that it's a u-joint since it only appears when pressure is transfered through the drivetrain............



    <font color=red>PHOTO ALBUM-</font color=red> <a target="_blank" href=http://albums.photopoint.com/j/AlbumList?u=1289798>http://albums.photopoint.com/j/AlbumList?u=1289798</a>.......<font color=blue>TRUCK & HIKING PICS</font color=blue>
     
  7. Pugsley

    Pugsley 1/2 ton status

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    Re: OK GUYS- bad metallic rattle!!!

    Mine was the one on the slip-yoke end, and it managed to tear the hell out of the yoke when it let go pugsley.alloffroad.com
     
  8. riz

    riz 3/4 ton status

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    Re: OK GUYS- bad metallic rattle!!!

    <font color=purple> Check the metal sheilds that go around your exhaust too, sometimes they rattle to beat the band !!!!!!!! Very easy to fix too !!

    L8r,
    . Riz . <a target="_blank" href=http://www.geocities.com/rizmonkey>www.geocities.com/rizmonkey</a>

    <font color=purple> BOW CHICKA BOW WOW !
     
  9. Can Can

    Can Can Pusher Man Staff Member Super Moderator

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    Re: OK GUYS- bad metallic rattle!!! *****UPDATE******

    I took the truck down to a buddy's shop this afernoon and we got her up on the hoist and then up on the axle hoist. I got in and put her in gear and feathered the gas with a foot on the brake trying to simulate the rattle.

    This is WEIRD- It sounds like the rattle is coming from about 6' forward of the rear u-joint, INSIDE the rear driveshaft!!!!!!

    Is there something wrong with my driveshaft, or is the u-joint still the culprit and somehow the sound is travelling up the driveshaft to where it hollows out and casuing an "audible" illusion?

    Comments please- only three days until I'm supposed to go to the lake!!!!!



    <font color=red>PHOTO ALBUM-</font color=red> <a target="_blank" href=http://albums.photopoint.com/j/AlbumList?u=1289798>http://albums.photopoint.com/j/AlbumList?u=1289798</a>.......<font color=blue>TRUCK & HIKING PICS</font color=blue>
     
  10. Pugsley

    Pugsley 1/2 ton status

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    Re: OK GUYS- bad metallic rattle!!! *****UPDATE******

    I'd still put my money on the U-joint, and it's causing a weird harmonic through the driveshaft.

    Dos mas Tecates!!!
    <a target="_blank" href=http://pugsley.alloffroad.com>pugsley.alloffroad.com</a>
     
  11. BowtieBlazer

    BowtieBlazer 1/2 ton status

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    Re: OK GUYS- bad metallic rattle!!! *****UPDATE******

    throw on a new u-joint at worst case to trouble shoot it...its about 13.99 for a lifetime warranty one and chances are if you dont know the last time it was replaced I'd replace it

    1985 GMC C-10 Shortbed
    1984 Chevy K-5 Blazer
    1982 Chevy C-10 Longbed
     
  12. rampage

    rampage 1/2 ton status

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    Re: OK GUYS- bad metallic rattle!!! *****UPDATE******

    I agree with the u-joint. More than likely it's the rear u-joint that has litteraly turned the needles into dust. If this is still the factory u-joint it will be hard to remove because of the nylon insert. U-joints are cheap and it probably needs replacing anyway and if your buddy has a hydraulic press then this won't take more than 30 mins to do.

    <P ID="edit"><FONT class="small">Edited by rampage on 08/23/01 04:51 PM.</FONT></P>
     
  13. k5blazerus

    k5blazerus 1/2 ton status

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    Re: OK GUYS- bad metallic rattle!!! *****UPDATE******

    when mine made that sound my friend saw what looked like a pinion gear shooting out of tne diff cover then we stoped and we also noticed it went through is radiator that day sucked. but best of luck to you
    colin

    IF its not broke , break it and upgrade it.
     
  14. jarheadk5

    jarheadk5 1/2 ton status

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    Re: OK GUYS- bad metallic rattle!!! *****UPDATE******

    Look real closely at the forward (T-case) end of your driveshaft. Is there a balance weight there? If so, how does it appear to be held on? Spot welds? Rivets? Is the weight secure? Maybe something IS rattling around inside the shaft, like a rivet bucktail or a broken-off piece of weld bead. OR, maybe the shaft has a real small crack at the forward end, oriented so that under acceleration it "opens and closes" harmonically, and while coasting it closes tight.
    There's my 2 cents...

    It's a happy day in Marine Aircraft Group 49... 405 is ALIVE!!
    [​IMG] <font color=green>Semper Maintenance!<font color=black>
     
  15. Can Can

    Can Can Pusher Man Staff Member Super Moderator

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    Re: OK GUYS- bad metallic rattle!!! *****UPDATE******

    The weight is there and looks perfect. I'm leaning away from thinking that something might be insode the driveshaft, because the sound only occurs at light throttle- you would think if something was loose that the sound would be heard constantly.

    I was also considering the fact that there might be a crack in the driveshaft, but I'm almost positive that it would cause a rattle even more during heavy acceleration. The only time I hear it is when I apply very slight pressure on the pedal when I'm at city speeds.

    Anyhow, thanks for the input, Jarhead. I'm going to install a new u-joint tomorrow and take it from there. I'll keep you guys posted..........



    <font color=red>PHOTO ALBUM-</font color=red> <a target="_blank" href=http://albums.photopoint.com/j/AlbumList?u=1289798>http://albums.photopoint.com/j/AlbumList?u=1289798</a>.......<font color=blue>TRUCK & HIKING PICS</font color=blue>
     
  16. coopertwpk

    coopertwpk 1/2 ton status

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    why are you going through all of this when 4 7/16 " head boltshold your drive shaft in place pull the damn thing and check it before it decides to make a beer can tossing hole in the back of your blazer.

    88k5 silverado w4"lift <font color=orange>d44 and corp14ff</font color=orange> with 4.56s
     
  17. Can Can

    Can Can Pusher Man Staff Member Super Moderator

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    uhhhhhhhhhh..............thanks for the advice. That's exactly what I was going to do today. Just looking for other ideas, that's all. That's kind of what the site is for isn't it?[​IMG]



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  18. rampage

    rampage 1/2 ton status

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    Re: OK GUYS- bad metallic rattle!!! *****UPDATE******

    Isn't the driveshaft sealed? How would anything get inside of it? Better yet, how would you get it out?
     
  19. Pugsley

    Pugsley 1/2 ton status

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    Re: OK GUYS- bad metallic rattle!!! *****UPDATE******

    Some of them do have a small hole in the center of the yoke at the axle end - about 3/8". But there really isn't any way for anything to get in it except for weld slag from the balance weights.

    Dos mas Tecates!!!
    <a target="_blank" href=http://pugsley.alloffroad.com>pugsley.alloffroad.com</a>
     

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