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I have had a noise I experience on my 08 Civic EX since new upon a cold start only when it's freezing or below. The lower the ambient temperature the worse the noise is and the longer it lasts. When it's not too cold it goes away in 30 seconds. When it's colder it can last a few minutes. The noise is only noticable when driving around the yard or at parking lot speeds and only happens when the car is in reverse or drive. The noise comes from the area of the engine where the pulleys are. I took it to the dealer last week and left it over night so they could test it first thing during the cold of morning. Well, they said it was a drive belt tensioner and ordered the part and replaced it. I took the car home only to find out the very next morning that nothing had changed. I took the car in today for the same thing. My question is what could it be? It's still on warranty probably for the next four months or so. I'm afraid they'll just try and blow me off tomorrow. If they do what do I say? After all, they believed strongly enough that it was a problem for them to replace the belt tensioner so I would hope they don't come back with "we researched it and it's normal" Any ideas, insight or suggestions would be gladly appreciated. Thanks.....

 
Rep Power: 812

maybe a loose heatshield rattle?

 
Rep Power: 0

UPDATE!

Gearbox: That's exactly what it sounded like but not even close.

Okay so they had replaced the belt tensioner. I take it in again and they said they couldn't really hear it and asked if they could keep it another night which pretty much meant they had to keep it the whole weekend. I said sure, it has to get fixed. Well, they tell me they replaced the drive/alternator belt and they can't hear it anymore.. I say sure they're just grasping at straws I think but what a ya know the noise is gone! Apparently the bad tensioner messed up the old belt and it was slipping is what I was told.