So what exactly is rattling on my exhaust?

[NiteKids]

there's always this nasty rattle in my exhaust when I first turn it on but it goes away once everything warms up.

heat shilds?

Bad gasket?

Exhust bolts are not tighted enough?

[Dousan_PG]

which of those 3 have you already checked? why dont you check it first and come back.

[NiteKids]

Ha good idea! But I have a feeling the shields in my dummy cat (The one that comes hollow on S14 where a cat normally would be on any other car.) is what is rattling. Hmmmm

[DRIFTING_SIL_EIGHTY]

theres a rattle on my exhaust to. but not sure if its an exhaust noise. i have a hole in my cat right now and at 3000 rpm i hear it. it dissapears above 3000 and below. not sure what it is and im also thinking it might be my tranny ??? what do you guys think ? ima lift it up today and try to figure it out. did all 95 and up 240 cats dummies ??? i need one bad since mine has a hole in it.

[Yoshi]

I had this problem back when I had my stock one fixed.

Get under your car and see if any of hangers are rubbing on the inside of your bumper. the hangers have very little clearance (on s13s anyways), and much longer than stock, OR fatter than typical gaskets could be enough to make it rub when the engine is running (the whole exhaust system moves back about 1/4 of an inch, then contracts as it warms up).

2 mins with a sawzall fixed my issue, you should check that out first, easiest fix :)

[Dunkee]

Originally posted by NiteKids
Ha good idea! But I have a feeling the shields in my dummy cat (The one that comes hollow on S14 where a cat normally would be on any other car.) is what is rattling. Hmmmm
That's where my problem was but not inside the cat. Do you mean the cat after the headers? if so, it's just the outside heat shield cover. Paid $20 bucks to get it removed.