2008 Cobalt LT Knocking. - Chevy Cobalt Forum / Cobalt Reviews / Cobalt SS / Cobalt Parts
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post #1 of 4 (permalink) Old 04-02-2013, 12:43 PM Thread Starter
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Unhappy 2008 Cobalt LT Knocking.

2008 Cobalt LT w ECOTECH 2.2L. Was not maintained at all. It has developed a knock very recently.

Suspected Rod Knock (Hope for the best, plan for the worst).

Pulled the oil filter and drained the oil, found some small metal shavings (silver in color) in the filter. Dumped some oil treatment and new oil in, sound still there. I have heard multiple opinions on what could be wrong from broken lifter, slipped bearing, rod knock.

I have yet to bring it to a mechanic and get real diagnostics because I would like to save as much as possible, I am a poor man :(.

I have considered, rebuild, re manufactured crate engine, maybe try to pull one from a junkyard and hope for the best. OR just trade it in and try to get another car.

So my question is: What would you guys do ?
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post #2 of 4 (permalink) Old 04-02-2013, 02:25 PM
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In my technicians opinion, hmmm...well metal shavings coming from the near the filter area would be internal components not having proper lubrication to cool the parts down. Sounds like someone didnt do an oil change til it was down to the very last quart of oil. You may have warped parts as well, (valvetrain and bottom end). Its very hard to judge from the actual source without looking at it.

I would suggest a new motor, it will save you grief and dispair without any worries of future parts wearing abnormally, but if you cant afford one, you might want to consider what we call "overhaul" engine build. It uses slightly used engine components and saves you some dough, but in the long run, there is no "guarantee" to last as long as brand new OEM engine.

I would not encourage junkyard blocks for something you would use and rely on for transportation.

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post #3 of 4 (permalink) Old 04-02-2013, 02:29 PM
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You spun bearings unfortunately. Stop driving the car if possible. If not possible, you're gonna need a new longblock as soon as you can. If you want to spend 30 bucks to see if a new rod bearing set will work, try that first. Would only take you a few hours. But if you have metal shavings everywhere, I suggest a new block.

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post #4 of 4 (permalink) Old 04-02-2013, 02:38 PM
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Originally Posted by BankerBalt View Post
You spun bearings unfortunately. Stop driving the car if possible. If not possible, you're gonna need a new longblock as soon as you can. If you want to spend 30 bucks to see if a new rod bearing set will work, try that first. Would only take you a few hours. But if you have metal shavings everywhere, I suggest a new block.
Sounds like it. I know if you do an oil change and spot the oil coming from the drain plug all metal sparkily, not good. Just remember, oil lubricates all metal parts internally in the engine. Try to imagine a cycle of travel it goes through, thats what oil does. Oil gallery, bottom end, bottom half of piston during compress stroke (hence oil ring on each piston), camshafts, valves, etc.

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