Hi guys,

I have a 08 G35 sedan, 5AT. It has stock exhaust except for the muffler end.

When the car is warmed up, there’s exhaust (or under the car) rattle at D gear position with A/C on or when I raise the RPM just a bit.

I tried to tighten all the head shields after catalytic converters with clamps, remove all clamps and tried to bend head shields to be away from exhaust pipe, but the rattle is still there.

It doesn’t rattle when the car is on going.

Here’s the YouTube link that I recorded:
https://youtu.be/P6K9rKc0f90

(rattle noise from 0:22 and 0:54)

Any idea how to get rid of the rattle? 🙏🏻

 

All my exhaust rattles were from the heat shields so I removed them all since they trap moisture and cause premature failure .

 

Thanks for the reply. Is it safe to remove all head shields? I heard much heat will come into the cabin..

 

Yes it is. You can confirm with a muffler shop.

 

The heat shields matter when the catalytic converters die a horrible death. At that point the element will be literally glowing orange and dripping on the ground. Until then the heat shields on the cats will HELP but the ones glued to the floorpan themselves will suffice. I've seen MANY Z/G cars with the heat shields removed from the cats, never seen one that was a problem but they can be welded on the sides so they can't ever rattle and will work just fine. It's up to you.

One trick I use all the time to fine heat shield rattle is get some heavy duty earth magnets, Amazon usually has vendors that sell 1.25" circle ones. Stick those on the exhaust system where you suspect rattles. It will IMMEDIATELY damp the sound when you stick a magnet on the rattling part. Almost literally works every time and saves a ton of time finding that f'ing rattling sound.

If the rattle only shows up while driving at certain rpm you'll have to selectively move those magnets around to find it. It's a process of elimination.

 

i really appreciate your detailed answer. Could you please show me a picture or sample how and where I should the earth magnets? Should I put the earth magnets between the exhaust pipe and headshield or right below/top of the head shields?
(how should the magnets be thick to dampen the rattle?)

 

Basically the magnet just adds mass and magnetic clamping force to the rattling object which will either stop the rattling sound entirely or make it sound significantly different (lot deeper sort of "thumping" sound rather than the really high pitched tinny rattle sound it would normally make.

I usually would just stick them on heat shields, near hangers, near flanges, up on the header heat shields you can fit a couple. Then reproduce the rattle sound and see if it's gone or at least changed in tone. Now start subtracting magnets 1-2 at a time until it makes the rattle again.

I have a whole box of random sized magnets but these neodymium ones are usually my go-to. Just a fair warning they're EXTREMELY magnetic, don't accidentally get one stuck to any painted surface on your car like the fenders, you WILL damage the paint trying to remove it! Don't ask how I know this...


Also, don't use fishing magnets, those things range from like 400-1200 lb magnets and if you get it stuck to a flat spot on the car you might not get it off without damaging something. I've seen those magnets used to pull incredibly heavy objects out of the river, i-beams, sunken boats, safes, etc. There's a town nearby that's underwater (planned by the Army Corps of Engineers when they built all the dams on the Columbia River) and people used to go magnet fishing all the time. They would use a winch and dozens of buoys to pull up extremely heavy stuff with a magnet...

 

Thank you so much for the detailed answer with explanation 🙏🏻

I will order the magnets and will stick them to the heat shields area. I will post a new thread with video after getting magnets.

Thank you again and have a wonderful weekend 🙇🏻‍♂️