Today I was doing some work on the monte, and I had installed a Walker downpipe from autozone (figured i'd be getting a better downpipe in the future) a while ago but the heatsheild around it was causing rattling when I started up the car until it warmed up so I decided to take it off today.

Noticed that I was getting a VERY loud rattling which I initially thought was coming from the engine but I narrowed it down to the car. I should mention we used the old gaskets which werent too butchered so i'm wondering maybe that could be causing the rattling.

It's RPM dependent and will only do it at certain RPM's, never at idle. It's annoying as anything, and I'd really like to get it fixed. I don't want to replace the whole downpipe as i'm going to be getting a Z3 turbo in the next 2 months for it, so it's kind of pointless to get a whole new downpipe when i'll get a turbo downpipe with the kit anyway.

So has anyone experienced this and can point me in the correct direction to fixing this? Should I try replacing the gaskets or is the cat shot already?

 

If the bolts are all tight, using the old gaskets shouldnt cause a rattle. Im not sure if they use a donut gasket or a flat gasket. If they use a donut gasket it could be rattling around in there if it is really loose, but you would probably hear an exhaust leak as well. I would make sure the bolts are all tight to narrow that down. Then I would look and see if it is possibly rubbing up against the car somewhere. When I put my new catback on, I had to bend the front most hangers a bit and I bent them in a way that they rub the floor of the car. I too have a rattle at a certain RPM range. Seems pretty similar to what you are describing. If the bolts are tight and it isnt rubbing the car anywhere, I would check to see if maybe the rattling is coming from the cat or the heat shield around it (assuming thats not the shield you said you removed). I have used mechanics wire around cat heat shields before to keep it from rattling. If you wrap it around the shield and twist the two ends together real tight, it can temporarily get rid of the rattle. Its a temporary solution, but if you are just going to replace it, it could work well for you for the moment.

 

The whole car huh? Really narrowed that one down, lol- just thought it was funny...

 

I thought it was too. Mabye he meant cat??

 

It's not hitting your firewall??

 

Yeah I meant cat, hahah. Well I kinda stepped on it today getting on the freeway and the car backfired pretty loudly and the louder rattle went away but the exhaust sounds way different than it did, like it's leaking. i'm wondering now if it's really the donut gasket and the exhaust is leaking. the engine bay smells of exhaust/gas. Any more ideas?

i'm going to buy new gaskets for it and replace em on wensday, hopefully that will do it? i'll keep you guys posted.

 

I put a new resonator on about a year ago, but the installer didn't put those rubber pieces on that holds it from dragging, the car sounds like it could be a little quieter, should I replace the gaskets from the cat and the manifold?