Recently had a new sound develop in my 2007 Honda Fit Sport, audible at idle. Stuck the car on jackstands, started it up, and soon found the issue: one corner of the catalytic converter heat shield was loose. Hopefully this video will be helpful to you if you run into a similar issue with your Fit.


Note that, while yes, it'd be easier to simply remove the heat shield by cutting it off or somehow getting those rusted fasteners to cooperate, the heat shield does protect your car from burning to the ground if you ever park on a dry, flammable surface (e.g. leaves, dry grass).

Update 7/6/2017:
3 years after my fix, the shield has been through enough winters that it had rusted away to the point that it was only connected on one of the 4 connection points and was generally loose and prone to making noise. I un-did my clamps (which are surprisingly still in usable shape) and ripped the two halves off. I'll just need to be cognizant about where I park now (e.g. not parking on top of a pile of dry leaves).

 

I had the most annoying loud rattle one day and eventually my bottom shield fell off into the road while driving. Luckily no accidents occured because of it.

The rattle went away for a while until the top shield then started rattling slow in reverse and at idle.

I used 2 clamps, one at the front and one at the back of the converter, snugged them up tight and its been pretty quiet since.

 

I remember this happening on my Civic many years ago. What a pain in the ass.

 

I have had to do this fix twice, once at the front of the shield and then 2 years later at the back when it rusted loose (today)

The rattle almost sounded like a squeaky belt sometimes.

I used 14 gauge copper wire that I had on hand and twisted it till tight. It has stood up well to a few salty Canadian winters.

 

We had a big rattle...traced it to the hood support rod. Tied an elastic velcro to the middle of the rod, and pulled it toward the top of the radiator...no more rattle.

 

Same issue with my mom's three year old Ford.
I believe it is because she lives next to the sea where corrosion is high and the cheap materials involved. Fixed in the same way.

 

Mine fell off about two and a half years ago. Maybe "fell off" is not the correct way to describe that. Dragging along the ground for ten miles and then knocking it off with a broom handle is closer.



You can see where it came in contact with the ground!

 

Update: 3 years after my fix, the shield has been through enough winters that it had rusted away to the point that it was only connected on one of the 4 connection points and was generally loose and prone to making noise. I un-did my clamps (which are surprisingly still in usable shape) and ripped the two halves off. I'll just need to be cognizant about where I park now (e.g. not parking on top of a pile of dry leaves).

 

I replaced mine when they started to rattle. I took the extra step of spray painting the shields with high temp paint and they seem to be holding up great so far.

 

Good call on the paint, especially in upstate NY where things seem to rust even worse than our stuff.