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Engine/flexplate noise. Please Help!!

Discussion in 'The Garage' started by mofugly13, Jun 19, 2003.

  1. mofugly13

    mofugly13 1 ton bucket of rust Premium Member

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    I have a "clacking" noise coming from under my blazer. It changes with motor rpm. When I crawled under to check it out the noise sounded like it was coming from the flexplate. I inspected the flexplate al the way around with a strong light and can see NO cracks. I just had the tranny rebuilt and a new flexplate installed 7 months ago. It is still under warranty so I took it to the tranny shop. As soon as I drive in the guy says "sounds like your flexplate." They kept it for a day and did numerous test drives to try and diagnose the noise. The guy tells me he cant see that its anything wrong with the flexplate, but drive it until it gets worse and bring it back and he'll check again. So now I think it's something internal to the engine. I made sure all the rocker arms were tight. Stuck lifter? Collapsed lifter? I've heard of this but do not know the symptoms. It started quietly about a month ago, but now it's gotten pretty loud.

    Here are the symptoms.
    1. "clacking noise that sounds like a cracked flexplate
    2. does not make noise on startup, but as blazer comes up to temperature, the noise gets louder.
    3. noise goes away when I accelerate, and when I decelerate (coasting w/ my foot off the gas)
    4. noise is loud when I get up around 50mph and am giving it just enough gas to maintain speed
    5. at idle it only makes noise in 'ParkP and 'Neutral.

    So it makes the loudest noise when there is little to no load on the engine, or when engine braking. So my questions are:
    1. What is the most likely causeof this noise (besides the flexplate)?
    2. What do I have to do to fix it.

    If it turns out that it is something internal to the engine then I just want to quick fix it so it lasts long enough for me to save for a GM crate 350.

    A little background on the engine:

    According to the PO it's a rebuilt 327 with 8,000 miles on it. But he said the same thing 'bout the tranny and that took a $hit two weeks after I bought it. The dipstick the PO had on it was way longer than stock, it practically was laying in the bottom of the pan. Which, now that I think of it 's a pretty sweet mod 'cause then you're NEVER low on oil. /forums/images/graemlins/rolleyes.gif The first time I drained it I think about a quart and a half came out. The valve stem seals were shot and I changed those. While readjusting the valves I find that my #7 intake lifter is collapsed. When this noise first started I dropped the pan to take a look and change the oil pump. When I had the pan off I decided to check out a rod bearing and the bearings were worn down to the copper; the journals had grooves in them resembling the edge of a dime. So it's definitely had oil starvation problems before.

    To those who try to help me, Thank You.
    /forums/images/graemlins/usaflag.gif
     
  2. Confedneck

    Confedneck 3/4 ton status

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    Re: NEED HELP QUICK diagnosing engine clatter.

    first off... i want to see a picture of your truck with the 91 front end... and

    if it gets louder with engine temperature... its internal to the engine i would think... not a heavy line kinda guy here...good luck
     
  3. mofugly13

    mofugly13 1 ton bucket of rust Premium Member

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    Re: NEED HELP QUICK diagnosing engine clatter.

    Here you go

    [​IMG]
     
  4. Confedneck

    Confedneck 3/4 ton status

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    Re: NEED HELP QUICK diagnosing engine clatter.

    thats pretty sweet lookin...find anything with the engine noise yet?
     
  5. Smitty

    Smitty 1/2 ton status

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    Re: NEED HELP QUICK diagnosing engine clatter.

    I'd check the crank end play to see if your thrust bearing is worn. I had the problem on my 350 and finally got around to tearing into it to find the problem. Turns out the thrust bearing was worn allowing a counterweight to start coming in contact with the block.

    Smitty
     
  6. mofugly13

    mofugly13 1 ton bucket of rust Premium Member

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    Re: NEED HELP QUICK diagnosing engine clatter.

    ttt /forums/images/graemlins/1zhelp.gif
     
  7. mofugly13

    mofugly13 1 ton bucket of rust Premium Member

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    Re: NEED HELP QUICK diagnosing engine clatter.

    C'mon guys. I had to take a road trip in my GF's jeep last weekend. /forums/images/graemlins/1zhelp.gif
     

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