6G Celicas Forums

Hey, had a rattling problem somewhere in the exhaust recently which I believed was the flex pipe, had it replaced and the noise is still there so I'm fairly sure its the cat, now as far as I can see in the Australian ST204 there is only one cat which is on the manifold? so I looked up on Ebay and they seem the most expensive ones and as for getting them in Australia I'm sure they are super expensive so I have a couple options.

I looked at my friends mums celica recently and noticed it had headers and where my cat was, it looked to have none and the o2 sensor was lower, why is this? would there have been a cat in there that couldn't be seen perhaps?

another option is perhaps gutting the cat until I find one at a wreckers or something, I've heard people say this lowers power and makes it louder, I've also head it makes it no louder and no more or less power, whats really the answer?

thanks, this is driving me crazy.

This post has been edited by Euphoria: Apr 12, 2010 - 11:30 PM

This is the only cat I could see.

i would say on the headers, the o2 sensor is lower just because of the design 4-2-1 (if it is that type). most headers i seen on any car usually has the sensor slightly lower. On my car I only have 1 cat. converter also, its the same as yours. Also removing the cat. just frees up the flow of the gases. As for noise im sure that the noise level will go up slightly or alot.

Right, no cat, slightly louder, more straight flow. Aftermarket headers has the o2 sensor location slight lower. cali spec celicas have two o2 sensors.

Given he's in Australia, I doubt he was seeing much in the way of California Celicas.

Your Celica appears to be equipped with a 5SFE, which had its primary cat directly under the log-style manifold (single-piece extractor). It effectively acted as the manifold's collector.

Your friend's mom's Celica might be another model, or have received an engine replacement from a Camry. The 5SFE in the Camry received a manifold with separated runners (4-1 or 4-2-1 extractor design). This places the catalytic converter much lower in the exhaust setup.

However, I'd guess that the rattle you're hearing isn't coming from inside your catalytic converter. Rattles from the exhaust are typically due to the hangers. A hanger might have slipped loose, the rubber connecting the hanger on the exhaust to the hanger on the car might have ripped, or -- as is usually the case -- a weld has broken. As the engine vibrates, you get a rattle.

Easy test: set the car up on a lift and do what you have to in order to get the rattle to sound (I had to pull the emergency brake and put the car into reverse). Then grab the exhaust (I suggest a heavy glove). Then it's just a matter of finding which hanger is rattling. I managed this without putting the car on a lift, but I'm slender enough to reach the exhaust while the car's on the ground.

nah I am pretty certain its not the hanger.

Tap the cat with your fist, that should tell you if indeed the cat is making the noise.

it's pretty solid so it doesn't rattle but exhaust places told me it was rattling a little, i don't think i can tell until i take it off.

Well guys a couple weeks ago I took my cat off and shaking it around had no noises and it looked in good shape both ends, tapping it with things it didn't rattle.

as that wasn't the culprit I didn't gut it as Id rather a car that was good to the environment rather than getting 0.2hp lol

Put it back together and the noises are still there, only now its at different revs, VERY WEIRD.

The only thing I could really point out was the Gasket between the cat and manifold which was in 3 parts, looking at this diagram below 25576 is the part I'm talking about, mine was in 3 parts that seemed to sit together.

Anyway this is the rattle?

well I picked up a stock manifold and cat, noise still there! so I don't know where to start, what else can cause rattles?

It rattles at specific revs, you can't hear it directly in front of the engine as the engine noise overpowers it but you can hear it in the car with the windows down coming from the engine bay area, you can even hear it outside the car, im so sick of it haha.

Anyway engine mounts could cause this? the front and rear have been replaced but the other 2 I haven't touched nor looked at.

thanks.

anyone?

Try checking the heatshields under the car and even in the engine bay. I had a loose heat shielf below the car and that was causing a rattling noise. Its possible that it would be that, but i could be wrong. Worth a try though.

Yeah I've checked all heat shields.

does it sound like this?



if so i can offer no help, but i have the same noise... lol. Sounds like... maracas?

Does sound kind of similar, I will have to get a video, I did one with my phone but its a ****ty recording.

well whatever mine is, it has been there since i got the car. I took it to toyota once and had them listen to the sound and they said its nothing to worry about................................................. but never proceeded to tell me what it was. It only happens at certain RPMs, very weird, but i've learned to live with it since it isn't bothering anything.

mines been there for a bout a year, at first you could only hear it revving up in neutral but now its when you change gears, even outside the car you can hear it, my friends said they heard it and I've heard it when the tyre place took my car for a drive.

Everything I've seen described in this thread still leads me back to suspect the hangers.

well had a good look over all the hangers, all have the rubber still there.

I did workout it doesn't seem to do it whilst the engine is cold, although I don't want to rev much past 3k when its cold.

I'm thinking its something on the timing belt area, or the alternator, anyway it could be a bearing in the alternator?

And if the only manner in which a hanger could rattle is for the rubber to disappear, you'd have eliminated that as a possible source.

However, as I originally posted:


Note particularly that last point, regarding the welds. The break doesn't have to be big. All that is required -- and all that is usually present -- is a hairline fracture. You actually have to get under the car and inspect each hanger by eye and by hand, at close range. Simply looking under the car to see if the rubber is present is no more effective than deciding your oil pan can't be the source of the leak because you can see the edge of the gasket.