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Discussion Starter #1
Goodmorning, so I replaced the valve seals in my 2003 touring 350z. At the same time I replaced all timing chain tensioners just for the **** of it. I drove it for around 850km and now after the car sits for a while, cools down, there is a terrible metal on metal grinding sound on startup coming from the engine bay. It only happens for about 2 seconds then disappears. After that the car runs just fine. Wondering if anyone has had this problem and fixed it? could it be that I put in a faulty chain tensioner? Or would it be more from mal-lubrication of the chain? I read a G35 thread describing the same symptoms my cars having. The result of that was a new engine due to metal shaving being circulated throughout the engine. He said the best way to diagnose his particular issue was to drop the oil pan and check for shavings. I'm going to do that tonight but what are your opinions on the grinding sound?
Thanks
 

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Wow- the timing chain is designed to last the life of the VQ engine. I wouldn't replace it unless absolutely necessary. Let us know what you found when you dropped the pan.
 

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Discussion Starter #3
So I took the oil pan off and found no shavings which is good. I would like to say that the "grinding" noise I described is inaccurate for what I'm experiencing. I would say it's more resembles slack in a chain, not grinding. Sorry about that
 

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Did you replace the chain tensioner when you swapped out the timing chain? Is there a chance an error is reassembly is causing the noise?
 

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Discussion Starter #5
Well I never replaced the timing chain, I replaced the valve seals and then the mechanic who I was working with noticed that one of the tensioners wasn't working properly. So we decided to buy new tensioners and replace the old ones. I would say that it's always a possibility that the tensioners or one of them is faulty. As for putting the engine back together properly I'm sure we did. The car runs fine, and it hasn't blown up yet. Haha
 

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VQ engines are precision machines. If there's a grinding noise upon startup, there's something wrong with either the part, or the way it was installed.
 
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