My car has developed a metallic rattle coming from under the engine area, but only when the car is cold. It starts rattling around 2K+ RPMs. After driving for a little bit the noise disappears. Seems to me like a loose heatshield that expands with heat but everything that I can see under the car does not appear to be loose.

Any ideas what to check? Car has about 92K miles, 2005 RWD sedan.

 

i have the exact problem sometimes. . . interested in some feedbacks

 

Does it sound like this?
AUDIO LINK
I had a zoomH2N mic taped under the drivers side control arm brace. Pointed towards the exhaust.
It sounds like rattling where the exhaust or the transmisson is.
I have to press the gas pedal at the right angle to hear it for a lenght of time.
I believe it only makes the sound when the car is warmed up.

I fixed it by taking a dermel to the exhaust sheild.
Right side by the flex.
http://www.flickr.com/photos/30488813@N06/7897253244/http://www.flickr.com/photos/30488813@N06/7897253244/ by http://www.flickr.com/people/30488813@N06/, on Flickr

 

Same issue here. Both my heat shields are loose.

Temp solution was a wire coathanger wrapped around and tightened up, but now one side rattles a bit with that.

Gonna try trimming some of it next

 

It could be the heatshield, but also check the driveshaft loop which is a curved metal piece that's supposed to catch the driveshaft if it falls (don't see that happening, haha). But that was rattling on my exhaust, so I just took it off and no more rattle.

 

Been hearing this lately. Annoying noise backing up every morning!

 

Mine was loose last year although it didn't rattle very much. When I had my coupe midpipe installed I had them cut off the heat shield as well.

 

Havent been on here in a while, I figured I would update this thread. It was indeed the heatshields, the passenger side was loose. Rust sucks. The drivers side was not loose, but it was getting there. My solution was tightening 2 large hose clamps around each heatshield. Thanks again for the replies.

 

RadioGuy, have the clamps held up? Your initial description sounds very much like what I've been hearing on mine for the last 6 months. I hear it when I leave work and accelerate with 50-75% throttle once I turn out of the parking lot. Hear it around the same RPM range, but only within the first 20-30 seconds the car is running. Don't hear it in the morning, but I don't accelerate that hard in the subdivision, and I'm guessing the source of the rattle is warmed up by the time I get to the main road.

Car's almost to 90K miles now, had it here in GA since fall of 2009, so I wouldn't expect to see much in the way of rust, but I haven't climbed that far under the car in the last few oil changes to inspect anything meaningful.

 

I swapped out my coat hangers to hose clamps. Been holding up quite well now

 

My loose heatshields solution is always as simple as taking them off. You won't miss them, neither will your car.

 

I put them on about 5K miles ago, so far so good. I'll take a look at them this weekend when I change my oil.

 

Been noticing this noise lately too. Tend to get it when the car is warm rather than cold. Most noticeable at idle, but also occurs at various RPMs, usually as they are falling. Gonna jack up the car to change the oil soon, so will check it out then.

'05 Sedan btw

 

I have the same rattle under the same conditions as everyone describes. I removed the rusted heat shields around the cats, but still have the noise. Where else could be source? Maybe the metal jackets over the y-pipe? This is not rusted but I see some gaps between the top and bottom shells of this jacketing. Where is this driveshaft support bolt that was mentioned?

 

I know this is an older thread, but I ended up here while looking for ideas on a rattling I hear that sounds a LOT like a heat-shield. I haven't confirmed the condition of my shields, but I think they're ok. What I found is something I want to share for anyone else looking for ideas on rattling sounds.

I have an '05 5AT Coupe, 113K miles. I'm waiting for a weekend with some free time to change the spark plugs, and still have the originals, which might be contributing to the issue for me. Also, I might have some carbon deposits, due the the age of the engine, but I flog my engine on a regular basis and occasionally dump a bottle of fuel system cleaner in, so I'd hope that carbon build-up isn't too big of an issue for me. When I leave work, I have a nice, 1/2 mile stretch of road right out of the parking lot, no traffic or intersections. I often accelerate at 1/2 - 3/4 throttle all the way up to 50 mph or so. When the engine is between 3K and 5K rpm, I can hear a very noticeable rattling/buzzing, almost identical to the noise my sister's 2.5 Altima had before I found a broken weld in a heat shield. It seemed to only make this noise under medium to ahrd acceleration, and only before fully warming up. It does it in winter, and summer, so even if the engine is still heat soaked with the water temp being aroun 120-130 degrees F, it will still do it. By the time I'm to the highway, I don't ever hear the noise again. I assumed this meant heat-shield, never suspected knock or ping, because I would expect that to persist or get worse as the engine heats up. However...

My car states that it Requires 91 octane. In my area, we have 87, 89 and 93. I used 93 for the first year or so, before I started using 87. I noticed no change in performance, even in summer months, and in fact, mileage seemed to actually improve based on actually calculation based on miles drive/ gallons put in at fill-up. Not enough to be sure, since it fluctuated from tank to tank, but at least enough to feel confident it was not negatively affected. I speculated (perhaps incorrectly) that due to the potential (up to) 10% ethanol that is blended in, the actual octane of the fuel at the pump might be higher than the stated, assuming the stated rating was for the base gasoline. (I've never found any way to find out if the ratings were based on the true value after any ethanol blending.)

On a hunch, I've put 93 in my tank a couple fill-ups ago, and it seemed the noise went away. After 2 tanks of 93, I went back to 87, and I heard the sound the next day, though not quite as bad as it had been. I guess what I've been hearing IS ping, and I'm going to continue with Premium gasoline until i get my plugs changed. Then I'll test again with Regular and see if the sound persists.