Slight metalic rattle when accelerating under load

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golftango

Member
:
2009 Mazda5 GT
Folks,

Recently I have been getting a slight metallic rattle when accelerating with a light load (i.e. going up slight incline, etc.). This only happens at low speeds and the RPMs around 1.5-2K. It is not a "knocking" sound associated with bad gas and I use quality fuel. Cannot duplicate the sound when standing still and revving. Any ideas?
 
My protege5 used to make the exact same noise. Used to bug me to no end, checked everything from heat-shield to rocks caught in the under-body. Never found it. I think it stopped after I got my valve cover seal replaced but that was probably just incidental. It's been replaced with another new low RPM grining sound.
 
Another idea....

I have heard some complaints on this board about a metal shield on the A/C compressor that can come loose.

Tape a cellphone to the underside of your hood and go for a drive while listening on another phone? (coffee)
 
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Since its only in low rpms, on an incline & on an AT, I think its the same thing I have heard on my Subie 4AT, Accord 4AT and possibly even my Daytona 3AT, but that was so long ago and that car was so abused, I can't be certain. I think its the tranny itself straining since its trying to pull the vehicle uphill in an extremely low-torque/low-hp situation. My suggestion: Use the manumatic and DON'T DRIVE UPHILL IN HIGH GEARS!
 
thaxman said:
Since its only in low rpms, on an incline & on an AT, I think its the same thing I have heard on my Subie 4AT, Accord 4AT and possibly even my Daytona 3AT, but that was so long ago and that car was so abused, I can't be certain. I think its the tranny itself straining since its trying to pull the vehicle uphill in an extremely low-torque/low-hp situation. My suggestion: Use the manumatic and DON'T DRIVE UPHILL IN HIGH GEARS!
Click to expand...

We're not talking Mt. Everest here. This is a slight incline, such as highway entrance ramps and hills that you could walk up barely breaking a sweat.

To say that for each incline you should be using the manual mode is ludicrous.
 
Well, regardless of the steepness of the incline, you aren't supposed to be putting a load on the drivetrain @ 1500 rpms. It wouldn't be any different than towing a boat on a level roadway @ 1500 rpms.

I'm not sure if that's what it is, either. Just that its been brought up by at least 1 other forum member a good year ago, and that it seems to be what I experienced. Oh, and the grade I was on wasn't too steep, either. It was right before the point when the trans would kickdown to a lower gear when the incline got steeper.
 
Cars can knock even with "quality fuel". Going up inclines of any grade with low revs makes the engine labor...
 
He's got a buzzing sound. Our engine will easily handle bad gas. The chance of knocking valves, IMO, is 0%.
 
I've experienced this too, on a gentle incline. The AT drops to the lowest gear and "chugs" a bit - try bumping into 4th.
 
Turns out it was the plastic shield under the engine/trans. The dealer hadn't tightened half the bolts and it was just buzzing around.
 
There is a multitude of things that could cause the noise. The low rpms just creates the frequency that causes this item to rattle. I've searched for the rattle in my Protege5 and couldn't pinpoint the sound from listening inside or out. I found it by mistake, it happened to be one of the brackets inside the dash the holds it up.
 
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