Rep Power: 0

Lately when I turn my engine on I'll get a rattle near the front. The exhaust is also now a lot louder near the front. I have also lost a lot of power I need to ride my clutch a little going into 1st and second.

I'm guessing it's my catalytic converter. I went under my car and tapped it and heard some rattling closer to the muffler side of the cat.

Does that sound like a typical broken cat?

If that's the case what would be a good cat to get, on a quick search I've seen some from 50-300. Also would I have to replace any gaskets or O2 sensor or any other parts?

My muffler was replaced about 2 years ago (still stock) but my headers are basically covered in rust. While I'm down there would it be worth it to replace them with performance headers? If so are the 4-2-1 the best to get?

My car is a 2000 civic ex only upgrades under the hood is a cold air intake. Any help would be appreciated I don't know a whole lot about cars.

 
Rep Power: 390

It might just be your heat shield... where did you tap?

And the race header is the best header for the D17, but it deletes the cat, but its pretty easy to keep the cel light from coming on.

 
Rep Power: 390

It might just be your heat shield... where did you tap?

And the race header is the best header for the D17, but it deletes the cat, but its pretty easy to keep the cel light from coming on.

 
Rep Power: 0

The heat sheild was off. I was tapping the cat itself. On the side that connects to the back end (muffler side) I was getting a rattle.

 
Rep Power: 0

It ended up being my downpipe and cat started to separate causing the exhaust leak and loss of power. I'm going to buy a new downpipe and cat anyone know the name of the gasket that goes between the downpipe and headers?

 
Rep Power: 0

Is it a doughnut gasket?

 
Rep Power: 332

doughnut, yes.

 
Rep Power: 813

the cat has 80k/8yr federal warranty fyi...

 
Rep Power: 0

gear box how much is the spark plug gauge (oppening) for a civic 2000 ex coupe???

 
Rep Power: 0

gear box how much is the spark plug gauge (oppening) for a civic 2000 ex coupe???

 
Rep Power: 813

hmm not sure exactly, my manual is only for 01+ but sparkplugs.com says it should be the same 0.044 inch

 
Rep Power: 260

what are symptoms of a bad cat? i get rattling/scratching/metal noises when i accelerate from a dead stop but never cruising or when it rains. and my banging the exhaust i also hear that there is something rattling inside, but i took it out and nothing. the cat looks okay from underneath but i havent taken the header off to check yet since its not a constant issue.

 
Rep Power: 813

well a cat can get clogged, that would cause a glowing header and poor performance. but also the materials inside can fall apart and start rattling around. this is less serious, since as the pieces break and become smaller, they will start coming out the exhaust. eventually tho the cat will not function as an air purifier and you will fail smog (the engine light will also come on due to low catalyst efficiency). but engine will not get damaged because exhaust can still flow freely. if there is no engine light, i would say youre fine for now.

 
Rep Power: 260

ya its just embarassing because there is this stretch of road at my college where where pavement sucks and theres a ton of stop signs, meaning acceleration from a stop, which causes a lot of noise underneath or towards the rear of the car. theres no noises on the freeway or at cojnstant speeds though and all the heat shields is not touching the exhaust at all. for some reason it started making noise after i got my front lca bushings installed but its probably coincidental.

 
Rep Power: 813

the energy lca bushings are quite noisy in the winter on bumpy roads, but its more of a squeaking/creaking sound not a rattle. if they are oem rubber bushings, you may want to make sure the suspension parts were tightened properly. seems like a big coincidence and it may not be exhaust related at all.

 
Rep Power: 260

but the sound is clearly coming from underneath the car not the front of the car where the lcas should be. also if it something was not tight wouldnt i feel make more noise as acceleration climbs high or more vibrations? the part i dont understand is that it wont make any noise in the rain ever. any ideas where i can start tightening with the front lcas?

 
Rep Power: 813

which lcas are they, oem? can you post some pic?

 
Rep Power: 260

i really doubt the front lcas werent tighten down or they are the culprit because the noise will only start when the exhaust is warm or after a drive. I'll never ever hear it as im pulling out or about to get on the freeway, but right after the freeway drive, ill hear it and it is on the passenger side mid section of the car where the exhaust is. I have a greddy sp2 catback so the piping is really big compared to stock. it doesnt look like it is hitting the heat shield at all, but my guess is that it expands after a drive and is hitting something? though it wasnt the case when i first installed it. Also if the car is still and im revving i wont hear it either. Would getting poly exhaust hangers help or would it make the incabin more uncomfortable for me?

does the exhaust shake more from a lower gear like from 1 rpm to 2 or so? because im having more noises in that range especially when i mash the gas pedal. after it reaches 3 rpms or at cruising speeds theres no noise. but if i let go of the gas and mash on it again i'll hear the noise slightly. My guess is the exhaust? especially since my cat converter looks fine, the honey comb structures still look like they are in tact. and plus the car is only 68,000 miles

 
Rep Power: 813

my best guess is the exhaust heat shields, youll be surprised just how much the exhaust moves around. i had this issue a while back and would constantly get rattles with aftermarket exhaust. after removing heat shields, not a sound. the shields are only there in case you park in grass and the exhaust starts a fire. and yes, heat shield rattling against the exhaust sounds very similar to when the cat converter pieces start breaking inside and jingling around. ive heard both. and yeah the most rattle occurs at idle and low rpms when the engine (and exhaust) is moving more.

 
Rep Power: 260

ya that seems to be the case, immediately after getting off the freeway the road leans to the right for water draining purposes and thats when I start hearing noise. on my way back to the freeway theres no noise because the exhaust is not warm up i'm guessing. btw aside from removing the heat shield can I bang on them or something? It's just really hard to imagine how it could be hitting because well theres like an inch of clearance still.

any ideas on how the noise started up months (at least 6) after i installed the exhaust?
and will getting poly hangers means more incabin vibrations for me?
thanks again

 
Rep Power: 813

an inch of clearance is like nothing. i had 2 inches and still had rattling. the poly hangers wont really matter, the exhaust will still swing around without fixed mounts. as for why it just started happening, i noticed that too. when i first installed, the stock hangers were pretty stiff, but the new exhaust weighed 40 lbs instead of stock 15 lbs so over time the hangers started to sag and get loose. i replaced with new, but it would just sag again. also the heavier weight gives the pipe greater momentum so when it moves, it has a greater tendency to keep moving until it hits the shield. stock exhaust is so light, it absorbs the impact and doesnt bang.

 
Rep Power: 260

that makes a lot of sense. i dont feel comfortable removing the heat shields though, so i might take a hammer and start banging on them?

 
Rep Power: 260

also dont you think thicker material hangers would mean less movement for the piping?
its interesting how I get a loud knocking sound when it rains but never a grinding sound.

 
Rep Power: 260

also dont you think thicker material hangers would mean less movement for the piping?
its interesting how I get a loud knocking sound when it rains but never a grinding sound.

 
Rep Power: 813

you can try the hangers, it may help a bit. theres nothing wrong with removing the heat shields, i put my hand on the car body after turning the car off and it never got hot enough to cause any damage. but if you want you can try bending them. the metal is pretty soft.