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Thread: 06 Envoy nasty sounds 1500-2000rpm

  1. #1
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    06 Envoy nasty sounds 1500-2000rpm

    So having an issue with my 06 Envoy 4.2l I6

    Sounds like iv probably blown the motor, although i don't know how... but around 1500-2000rpm there is a nasty knocking / clacking noise coming from the engine. In neutral it sounds like it was to break its self apart, under-load and driving not as bad, but still there.

    Some observations i have made. when the truck first starts up in the morning time, it idles rather quiet and smooth. once warmed up, its not so quiet anymore. and the knock comes and goes.

    currently i have a Check engine P420 code set. Poor catalytic efficiency, replaced the cat on it, light stayed off for 3 days and came back.

    I took the serpentine belt off and fired it up, still nasty noises. So i know its not a Alternator, Water pump, A/C power steering pump or pulley problem.

    ran some oil engine additives and restore type stuff through it, gave it a fresh oil change. No change in symptoms.


    Took a bit of audio of the noise its running.

    Any one herd this on a GM 4.2 Vortec engine? my next step will be to do a compression test, and pull the top of the motor and inspect the rocker arms. but im fearing the worst at this point.

    youtu.be/2TMXZW4V8Lg

  2. #2
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    Stickybongsmoking is offline Yes, this is gawd damn muthafockling CTD NUT.
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    Listening to an audio clip through a shitty computer speaker isn't terribly helpful....but it sure sounds like rod bearings to me. When you did the oil change, did you observe the condition of the old oil? Sometimes, you can see a bronze/copper coloured metallic film floating on the top of the oil which is bearing material.

    For a little while, rod bearings may not be audible on a cold engine until the engine warms up and the oil thins out.
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    Plus side, they are a dime a dozen for the whole truck, so finding a replacement engine should be easy.

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    Ya i agree it kinda sounds like a rod bearing, usually it will get really loud if you rev it up a bit and let off the gas fast. But by the sounds of it i wouldn't rev it up to high.

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    Replaced Engine, Noise went away =)


    wow i'm bad for late replies to my own thread...

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    Did you inspect the lower end when you had it pulled? What did it have for mileage?

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