Underbody rattling
 

Hey guys. Recently I removed and reinstalled my driveshaft and now I have an unknown rattling noise coming from what appears to be the driveshaft. Can anyone shine some light on this? It is driving me crazy. Thank you!

Attached is a video of the incessant noise



https://www.youtube.com/watch?v=hSg07vAY8Do

Get a piece of garden hose (or similar). About five feet long or so. Hold one end to your ear while you move the other end under the car. Be very careful if you get near any moving parts.

Edit: That doesn't sound like a drive shaft or u-joint to me. Sounds more like a small metal plate.

Did you loosen or remove the sub frame brace and heat shield for the resonators? Make sure these parts all torqued down.

@Flyfish I removed some bracing underneath the engine but none towards the back of the car.

I thought it was the heat shield but it sounds almost like a loose nut or bolt, Its really bothering me.

It's so loud, I can hear it at low speeds driving down the road.

I would uninstall everything and install it back again, it does sound like a bolt or a washer or something small is loose. It doesn't sound like a dreaded scraping or knocking sound which is good news. Does the sound change if you press the clutch or when your driving?

YES. This is what I thought too. Thank you. I just don't want to go through the trouble of doing all the work again.

Why did you remove and replace your drive shaft (not that I care), however, it may jog your memory into thinking about what else you did. Couple more questions; Is the noise in the video just from revving the engine, were the wheels in the air? What type of transmission? What else did you remove???

I was removing it to take the transmission out to service the CSC.

The noise occurs while driving and while in park. The revving is just to make it rattle louder at a certain frequency. 2 of the wheels were in the air yes. 6MT

Some exhaust pieces and a bunch of stuff from the clutch and clutch line but the noise seems to be coming from the mid/rear. I removed multiple wiring harnesses and random small things.

UGH. I for the life of me cant figure this out.

Maybe a nut, bolt or foreign object that was dropped into the exaust piping?

Another good guess! But I was knocking on different parts of the exhaust with my hand and I never heard anything rattling. I cant replicate it unless the car is idling at a very specific RPM. Its so frustrating.

Well, shoot. Here are my thoughts on this.... I think we can eliminate the driveshaft and clutch, since the noise happens when the car isnt moving?... unless theres a loose nut bolt or washer...
Make sure theres no contact with the heat shield...

That leaves the exhaust. When you say it happens at a certain frequency, perhaps it would be more accurate to say RPM? After all, the higher the RPM, the more airflow going through the exhaust, the more likely that airflow is disturbing whatever is loose.

I think the next step would be to start at the muffler... remove the muffler (completely off the car and hangers)... start the car and see if the noise/rattle is still there... itll be loud because of lack of muffler, but youd be able to tell.

If it's still there, remove the next exhaust section and start the car to see if it's still happening. Do this til you get to the last section you removed. And even then check the last section for any foreign object visually. Flashlight, camera..etc...

It's a pain, but itll definately help you narrow down the problem.


Edit... it goes without saying, do this outside.... have PLENTY of ventilation!!!!!!!

As I was listening to my front right end-link rattle yesterday, I was wondering if you every figured this out? :-)