Exhaust pipe?

[markzbornak]

Hi everyone,

This is my first post. I looked around, but didn't see a similar topic. If there already is, please excuse me.

I thought I might have a bad exhaust manifold. I took a look today and did not see any visible cracks or leak locations on the manifold or gasket. What I DID notice was that it appears that the exhaust pipe my exhaust manifold fits into is too large and also cracked. I was under the impression that the fit should be relatively snug, but I could be wrong.

I had a new catalytic converter put in back in July. I noticed that the car sounded a little louder than before. The noise has gotten worse and now sounds like the typical exhaust manifold noise. I really don't think it's the manifold now.

Is it possible that the mechanic used the wrong size pipe and it has now cracked causing the noise to become louder? If so, should I try to repair the pipe or replace it? Is it a DIY job? I have a bit of experience, but I do not own a welder.

Here is a link to a picture of what I am describing. I tried to make things as visible as possible. Thanks for any help!

[ilovecorollale]

I think that is a stock size one there. There's a flange/gasket that seals between there where the bottom manifold fits into that pipe, the gasket flange in between could be the problem for leaking? Or maybe else where like a punctured whole or so along the pipe.

Do you experience any power loss or decrease in mpg?

[markzbornak]

Hi,

Thanks for the quick reply! I SEEMS like the sound is coming from underneath the hood and not further down the pipe. I will check it tomorrow once I can get it up in the air.

Do you think this is the part I might need?

I have not noticed any decrease in gas mileage. Sometimes I feel like I am not getting enough power up hills, but that might be my imagination.

[EdW]

Can you get your hand up there to the coupling/flange where you think it's leaking from? If so, when the car is cold, put your hand there and have someone start the car. Feel around for the air leak. It's going to get hot, but you have a couple of seconds to try and feel where the air is coming out, and if it's as loud as you describe, should be fairly easy to detect. I'd start at the coupling, and if all seems well there, let it cool and then move to the next suspect area.

[markzbornak]

That's a really good idea. I can definitely get my hand down in there. I'm going to try it in the morning. Thanks!

[Bernie3]

You can also partially obstruct the exhaust pipe with a rag, just enough so as not to stall the car. The rag will cause back pressure and make it easier to spot a leak. Be sure to remember to remove the rag once you are done.

[randini667]

We used to call those the donut gasket, mine went out at about 109,000mi... But save yourself some time and pick up the bolt hardware kit too, because likely the bolts and springs are toasted and rusted.

-Rand

[WTFseabass]

i had this same exact problem a while back, I replaced those bolts and the donut that is in between the pipes...i also replaced the exhaust gasket and ported my stock headers and sounds and feels better...but i also did not have loss of gas mileage but lack of power when take off or going up mountains/hills...

[markzbornak]

Thanks for the help everyone. I felt around and it seems like it is coming from the flange gasket area. I got the car in the air and I do not see any cracks/holes in the pipe, so I think it has to be that flange gasket.

I got a replacement flange gasket, and I am planning on getting new bolts/springs today. Do I need to take the exhaust manifold off to replace that gasket or can I get to it another way. I looked underneath, and all the bolts on the hear shield over the exhaust pipe are rusted. I've sprayed them with PB blaster, but they seem to just be spinning. Should I try to pry that heat shield off or am I wasting time when I should just remove the manifold anyway?

Thanks again for all the help.

[EdW]

You should be able to get at the two bolts that attach the down pipe to the mainfold from under the car without removing anything. Just took a look at my 98 and you can see the top half of the bolt and the threaded manifold flange they screw into from the engine compartment. I mention this because you're probably going to want to put a torch on this flange area and use heat to try and free up the bolts. If they break in the manifold, you'll be drilling and tapping or using a nut on the top end of the new bolts. And before you screw the new bolts in, coat the threads with anti-sieze compound so that if you ever need to take it apart in the future, it won't be frozen.

[markzbornak]

Well, I got in there and the bolts came off very easily. I sprayed a little PB Blaster and waited a minute, then they came right off.

I don't know what I was thinking before about taking the manifold off. Once I took those bolts off, it was very easy to replace that gasket/flange. The old one was considerably smaller and looked worn.

The noise is significantly less now. There is still some other type of loudness in the exhaust system, but it's now down to the level where any mechanics that looked at the car said it was normal. I don't think it's normal, but maybe only another 8th gen corolla owner would notice.

I'm still wondering if the last mechanic didn't do something when they put on my catalytic converter in July. Maybe it's possible that a non-direct fit cat would cause the exhaust to sound a bit louder.

Either way, the major "tick tick" sound is gone and my power up hills is back!

If anyone has any further insight, I am all ears. For now, I am reasonably content.

I really appreciate everyone's help on here, and I hope that I can do the same for someone else in the future.

Mark