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Discussion Starter #1
Hey all ive got an 07 ss/sc and when the car gets to operating temp I hear a knocking sound coming from the cam sensor. I can feel it too when I hold a finger on it. No codes.
 

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Discussion Starter #3 (Edited)
Its a knock. Its not comimg from the botom end. I pulled the valve cover everything looks good. I cant afford to fix it so I hope it doesn't blow up.

---------- Post added at 07:56 AM ---------- Previous post was at 07:41 AM ----------

 

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Sounds like a possible rod knock. Just because you hear it on the top, doesnt mean its not coming from the bottom. Could also be a failing timing chain tensioner, which youre gonna want to do right away. Pull the valve cover again and push on all the rockers to make sure they are seated tightly.
 

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Discussion Starter #5
Comprrssion and leak down is great rockers are perfect. Chain and tensioner were just replaced. Its only at idle.
 

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Levee
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Sounds like a slight rod knock to me. That can be caused by having too little oil pressure at an idle and when you give it more throttle it builds up the oil pressure to where it should be. Changed your oil lately? If not, I would HIGHLY recommend putting in a quart or trans fluid in your oil and running that for about a day or so then change your oil. That will really help clean out the oiling system.

As banker said, Rod knock isn't always heard from the bottom, my evo when I spun my rod bearing and had rod knock it sounded like my cams were hitting the valve cover.
 

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Discussion Starter #7
Damn. Thing only has 100k and was well taken care of and never beat on. I changed the oil 1k miles ago.
 

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Chevy Customer Service
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Hi kyspe,

I'm sorry to hear of your vehicle concern. I cannot guarantee anything but I will be glad to look into this for you. Please send us a private message referencing your concern if any extra help is needed. I look forward to hear from you!

Kristen A.
Chevrolet Customer Care
 

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I'd say you spun a rod bearing and what you hear is the piston slapping the head. It could still run for a while but I think it's days are numbered. It isn't going to blow but it isn't going to get better.
 

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Discussion Starter #10 (Edited)
I just bought the damn thing 3 weeks ago. Why would it only knock at aperating temp? I thought rod knock was alot louder.
 

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Levee
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I just bought the damn thing 3 weeks ago. Why would it only knock at aperating temp? I thought rod knock was alot louder.
It appears to only knock at NOT (Normal Operating Temperature) because at NOT the oil is warmer and a lot thinner. Think of it a syrup. When refrigerated it is really thick, when warmed up, it's really thin and runny. Same goes with oil, the warmer it is the less viscosity it has, aka meaning the less of an "oil barrier" on your parts. Make sense?

Rod knock can be quiet and can be loud. Depends on how far the bearing has spun. See the thing is, bearings and what not are actually egg shaped, not completely round like everyone thinks they are. They are formed that way for a reason, now, if for some chance the bearing spins, it allows for extra movement of the rod on the crankshaft in the wrong spot and thus will allow for a free spin spot, and a much firmer/friction spot. While in the free spin spot the "knock" you are hearing is 95% of the time the rod re-connecting with the crankshaft. The other 5% of the time is actually the rod connecting with the crankshaft AND the piston slapping the bottom of the head. So there are variations to a degree on rod knock and serverity. I would have someone drop the pan and look at it if I were you honestly. It's really not that hard to do, and honestly, I can do rod bearings with everything still in the block. So it's not a complete engine tear down/rebuild, UNLESS, the crankshaft journal has been scuffed enough to need turned. IF that is the case, you might as well just pull it all apart and build it up.
 

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Discussion Starter #12 (Edited)
Hey thanks for the info. If the dealer wont do it I can do it myself. If I do have to do this myself mind if I pm you? Since comp and leak down are fine that means everything else is okay? Comp was 175 across the board. I forgot what the leak down was
 

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Levee
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You can PM anytime, doesn't matter. Its fairly easy to do for sure, just make sure you have a torque wrench (this is a requirement, NOT an option). After that everything is easy. If you have good compression and leak down was good too, then you should be fine with just replacing the bearings (again that is if the crank hasn't been damaged too much).
 

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Discussion Starter #14
Alright thanks. Ive some a few aircraft engines so well see how similar car engines are haha.
 
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