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Discussion Starter #1 (Edited)
I have a 2007 Cobalt LS, manual trans, with 137K miles. I noticed a bad rattle in the motor when I start the car yesterday, and the rattle has been constant. Other than the rattle, the car seems to run fine. The RPMs at idle and speed are normal. The engine starts and stops smoothly. In other words, everything but the engine's sound seems normal. I brought the car to the shop today (I've used them for a long time, and they've been trustworthy), and they told me that the timing chain tensioner or guides are bad. They said I'd need a new engine, so it's just time for a new car. Since the car runs normally other than the sound, do you think they might be jumping the gun when they say that the engine needs to be replaced? If the timing chain was slapping around like they said, wouldn't I be seeing issues with acceleration, RPM, and that kind of thing? Should I get a second opinion before getting a new car? The mechanic advised me to just carefully drive the home since I live nearby, then not drive it anymore.

Even if the timing chain situation might be more salvageable than they're saying, it might be better at this point to get a new car anyway. At 137K miles, I'd probably be running a high risk of my clutch or something going soon after I sink several hundred dollars into this repair. That's always a tough call, but I'm still interested to hear your opinion on my mechanic saying the engine was shot when everything seems fine other than the noise.

Thanks!
 

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I have a Cobalt LS, manual trans, with 137K miles. I noticed a bad rattle in the motor when I start the car yesterday, and the rattle has been constant. Other than the rattle, the car seems to run fine. The RPMs at idle and speed are normal. The engine starts and stops smoothly. In other words, everything but the engine's sound seems normal. I brought the car to the shop today (I've used them for a long time, and they've been trustworthy), and they told me that the timing chain tensioner or guides are bad. They said I'd need a new engine, so it's just time for a new car. Since the car runs normally other than the sound, do you think they might be jumping the gun when they say that the engine needs to be replaced? If the timing chain was slapping around like they said, wouldn't I be seeing issues with acceleration, RPM, and that kind of thing? Should I get a second opinion before getting a new car? The mechanic advised me to just carefully drive the home since I live nearby, then not drive it anymore.

Even if the timing chain situation might be more salvageable than they're saying, it might be better at this point to get a new car anyway. At 137K miles, I'd probably be running a high risk of my clutch or something going soon after I sink several hundred dollars into this repair. That's always a tough call, but I'm still interested to hear your opinion on my mechanic saying the engine was shot when everything seems fine other than the noise.

Thanks!
I just replaced everything (tensioner, chain, guides, sprockets, etc.) because I was having the same issues. You might be able to get away with just changing the tensioner (part shouldn't be more than $50), the only reason I replaced everything is to prevent a headache and I had the time and money. The tensioner is pretty easy to change as long as it hasn't completely fallen apart. What year is your car?
 

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Sounds like it's time to get your hands dirty, and even if it needs a new chain and guides it's not a bad job or even all that expensive to do. As long as it didn't jump time and smash the piston into the valves then the engine would be just fine after
 

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Discussion Starter #4
Thanks for your replies. So it sounds like you think this mechanic is jumping the gun.
 

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I think it's more or less that by the time you pay them to go through and replace everything you would almost be further ahead cost wise just putting a different engine in it. Honestly though it sounds like it's probably just the tensioner and as long as it doesn't fall apart it's only like 40 bucks or so and like a 15 minute job that's insanely easy to do. If you want to look into it further you could always pop the valve cover off and look at the guides.
 

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I would check if you have first generation tensioner and take it from there. If you have first generation replace it with the revised version, if the noise goes away like it did in my 07 and 08 then your good to go for a few years.



---------- Post added at 05:19 PM ---------- Previous post was at 05:17 PM ----------

First generation doesn't have bump on the head.

 

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Check what coby said and report back. I'd try the tensioner before an engine swap. Although they aren't bad and take anywhere from 6-8 hours with a hoist. I've done numerous
 

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Discussion Starter #8
Thanks again for your advice. I forgot to say in my first post that my Cobalt is a 2007.

I live in an apartment that doesn't allow its residents to do that kind of auto work in the lot, so I'd need to go to a mechanic for this job. But I decided that it's time for a new car anyway, so I bought a Civic this evening. I sweated taking long drives with my family in the Cobalt, because I felt like the car was overdue to break down. It's starting to look really beat, it's getting rust bubbles under the paint, and it's probably close to needing a new clutch. The car dealership said they'd give me a few hundred dollars for my Cobalt if I can get it to them in the next few days (although I told them about the noise and what the mechanic said, and they even said I could tow it in), so I'll take that and call it a day. Now I can start planning that across-state trip I've been wanting to take.

All the best with your Cobalts and future cars!
 
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