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rattle or slight knocking noise in engine

11250 Views 14 Replies 8 Participants Last post by  Leeann_93
Now that i have the brakes fixed i'm gonna move on to the next problem. I have a noise in the engine area that i can only hear at or around 1500 rpms thru the 2000 rpm range. It sounds like a piston rattle but only at those rpms. When it gets above 2500 rpms it dosent rattle anymore and it dosent rattle at idle either,dosent rattle at start-up. i dont think this is doing any damage to the engine ,there is no metal in oil . just wondering if anyone has had this problem or has herd of this problem. I read somewhere the flywheel might be cracked or it might be the torque converter, i just dont know . I thought i might try to get some of these problems taken care of while everything is slow and i had some extra time. :shrug:
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It's hard to say for sure without hearing it in person, but the 4.3 vortec is known for making balance shaft noise. My '97 does it a little. My brother's '99 makes a lot of noise. To me it sounds like main bearing noise. It's really never changed much over time on either of our vans and doesn't seem to be an issue in any way.

GM had a kit to fix the noise, but I believe it's been discontinued. I know one guy who disabled the balance shaft to stop his noise. The engine ran a little rougher at low rpm, but the noise stopped.

Here's a link ... eshaft.htm
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