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Transmission rattling?

Hey guys,

I just got this 2007 Mazda6 S Sport Value Edition for free from a family member. It has an automatic transmission.

While driving it in a parking lot I noticed that the car was make some kind of a rattling noise whenever I start accelerating slowly from around 1000ish rpms. After that the noise disappears. The first time hearing something like this was in a Prius I rented, though I don’t think this affects performance at all. I am wondering if this is normal?

Also the car has being sitting unused for about a couple of months before I picked it up. I noticed immediately a burning smell after driving it, somewhere under the driver side, which makes me suspect if it has something to do with the transmission. I know very little about fixing cars of course but I also own a manual transmission car, and this smell kinda reminds me of a burning clutch.

I drove the Mazda 6 from Utah to San Francisco. The car drives great. The transmission seems to work fine. No slipping. Driving around those hills in San Francisco just fine.

Would like to know your opinions about this. Thanks!

Transmissions usually whine rather than rattle. Noises are not normal.

Based on the statement that you got a burning smell, I’d guess you have a broken heat shield for the exhaust that rattles when you drive. It is a noise that can appear and then go away as you speed up.

The burning smell might also be a minor oil leak that dripped on the exhaust while it was sitting and then burned off. You might want to have that checked by your local independent mechanic.

The rattling noise is much more likely to be coming from a loose or broken heat shield on the exhaust system rather than from the transmission. In fact, I am going to go out on a limb and say that I have never experienced a transmission that made a rattling noise.

But, if you have suspicions regarding the transmission, I would assume that you pulled the dipstick and checked the level, color, and odor of the fluid. When you did that, what did you find?

The burning smell could be from something like a plastic grocery bag that got caught underneath the car, and that melted onto the exhaust pipe. I would strongly suggest that you take the car to a mechanic (a REAL one, not a quick oil change place), and have them put the car up on a lift. With any luck, they will find the source of both the rattle and the smell, and–more than likely–neither will be of a serious nature.