i have a 96 civic Lx and i put a aftermarket header with stock exhaust and i had a stupid exhaust rattle around 3k rpm i figured that the header was too big for the stock exhatus so that was the problem.

now i just put the same header on a 96 Si and i put on 2.5" stainless exhaust with high flow cat and resonator and i still get the same "tin can" rattle nosie around 3k rpm.

i realize that the header may be the issue but dose anyone have experience fixing this issue?

 

Man i have the exact same rattle and i have absolutly no idea whats causing wish someone here had the problem and fixed it.

 

Did you install new header and exhaust pipe gaskets and then torqued the nuts/bolts to spec?

 

Sounds like the exhaust has the rattle from you removing the cat. It's probably in the muffler, unless you installed it without spring bolts, then it could be the joint or the pipe moving.

 

Everything is done properly. Tightened enough properly with spring bolts and gaskets. There is a cat and resonator. In the stock y8 exhaust there is no cat in the header. Anymore insight?

 

so by rattle do you mean the exhaust note or is the car being vibrated by the exhaust hitting something ?. off the bat I would say heat shield(s) loose or it's just the exhaust this is a sohc after all what exhaust brand ?.

 

i just installed dc sports header in my 98 civic ex along with a magnaflow cat, and rest of it is factory....

I have the exact same issue, right around 3k rpm's I get a nasty rattle... I *think* there's a flaw somewhere in the connection between header and cat. I know my header/cat didn't come with any gasket or anything for this... what about you guys??

 

its the exhaust the bigger pipe and having a resenator and all that will change the sound of the exhaust so that the sound this one makes or it could be that you have broken honeycombs in your cat or some of your baffeling in your resenator is broke, or it could be your heat sheild like said above

 

You said 1996 SI. You're from Canada, yes?

1) Are both O2 sensors secured to the piping?
2) Is there any hangers for the header to hang onto?
3) Which gaskets did you install?
4) Have you checked the heat shield?

 

if you have a larger header and cat/test pipe and are running the stock exhaust that could cause some rasping/rattle. have you gotten under the car and looked ?

 

That's usually why people who correctly do the step-by-step called-for process, looking for loose hardware (bolts, clamps, shields, etc,) don't find it at first. Those broken pieces (if that's what it is) can really rattle when the exhaust sound-wave frequencies and pressure waves resonate to the right point. It frustrated me to no end in two civics. Both times, broken on the inside is what it turned-out to be.

 

Not sure name brand of header and the 2.5" exhaust is custom from teknotic here in Ontario. I used new exhaust gaskets from local part store. And cat is new like resonator. And there are no heat shields to rattle anymore lol. Not sure what to do anymore lol.

 

hmmmm. Assuming that you're getting the rattle during engine revs only (no transmission or wheel movement), AND - if everything is fairly new, AND if all of the connection bolts are verifiable tight, ***And still thinking exhaust system,*** I'd try this next... Usually not having help:

Process of elimination:
- Put it in the air (on stands).
- Check both the exhaust system sensors to make sure they're not in pieces. (a long shot that *should have showed-up as a check engine signal, but easy and good to eliminate).
- If they're good, and they probably are.
Doing the least and easiest first, next:
- Disconnect the system at the rear header flange only.
- Shake the disconnected cat-back sections from side to side and listen for your rattle coming from inside.

If it still doesn't show-up, there's nothing else that I can think of besides removal of cat-back components and checking again.

 

go there and ask Eric, colin or jay they'll help you out if you're really at a dead end


but i'm willing to bet it's something small and simple that's just being missed

 

My exhaust rattles only when the car is at full operating temp and at idle. Rattles near the header/cat flange, removed heatshields as well. Pisses me off.

 

Ya when I have free time ill probably go there. It's a 2hr drive from where I live now.

 

That may be a bad gasket or broken spring bolt? New gasket and bolt kit cost me $16 at local part store so give that a try

 

Ive got almost the same problem. Changed everything in the exhaust headers, bolts, gaskets removed every heatshield, even replaced the rubber the exhaust hangs from. I was reading someone that it could be the timing belt tensioner making the noise im gettin my belt done this week and il let you know

 

Double check that your O2 sensor isn't rattling against the shift linkage.
After market catalytics may be direct fit, but the bung is in a different location and your O2 is likely to rattle off of it.
That's assuming you have one installed of course.

Source: My 99Si does the same damned thing, I'm going to re-weld my direct fit cat at a different angle once I get the ball rolling on that car agian.

 

How tight should the spring bolts be?

 

The service manual extract that C0671 posted above states 22NM (16ft-lbs).

 

I have all aftermarket but I assume it's around the same. I'll tighten then some more and see if it stops.

 

I'm thinkin it's way more simple than all of this.. I have a 2000 civic with a B16 swap. full HKS exhaust including headers and no Cat. mine rattles at about 1500 and 3000 rpm. I've found that it's the S pipe rattling up agains the car itself. when I pull on the exhaust and let it go, you can hear it hitting the car. my old apexi exhausts was hitting the gas tank. this HKS Doesn't go over the control arm like the apexi did so I don't know exactly where this one is hitting but I do know it's exhaust to car contact and not a gasket or cat or spring bolt problem. not really sure how to remedy this though..