Did you replace your rear mount and still have a rattle try this?

[BTschakert]

Willie has some valid points below. Let me summarize this better.

-Rear engine mount if torn will cause vibration and movement.
-Where do rattles and noise generate from?
-Metal to metal contact.
-So trouble shoot those components rubbing against each other.
-Between the cats and exhaust system there are flexible gaskets which possible erode and/or sometimes forget to be put back in after service work.
-There are rubber band type supports at the lower cat and the rear of the exhaust system that are easily replaced if broken or missing as well. Mine on a Minnesota car of almost 11 years are still in good condition.
-In summary it is a two step trouble shooting process to evaluate your rattle/vibration issues. Hope this helps.

Original posting:
I have not seen this posted but if I'm wrong sorry but I thought I would share my results. I replaced my rear mount that many of us talk about and I still had a rattle. Digging around I noticed that the upper and lower cats where straight metal to metal and the sound of the rattle originated from this area. Looking at the BOM I was missing the Flexible gasket 18229-S3Y-J01 (for my 01 5speed). So I bought that and the flex bolts. Removing the flex bolts from a MN car after 10 years was a pain in my back side. Installed the new tapered gasket and wow. I have a new car for $16.39. I would even recommend checking this first before replacing the rear mount due to how cheap it is vs the rear mount.
13s3y01_b02.jpg

[Eli]

Excellent, thanks for posting.

[Kenpo]

Interesting, 01 shakes as well and cant figure it out. Checked all mounts and they're all ok. I'll have to check this out in my car. GOod find.

[Willie Williford]

A bad rear mount will cause a vibration or shake, not a rattle.
With the "doughnut" missing on the exhaust pipe, you probably had a very putrid smell of exhaust fumes. Seldom do they burn out, someone left it out during some kind of repairs.

Willie

[retepsnikrep]

I've had this rattling issue Willie and the little asbestos gasket had deteriorated and was rattling around inside the joint.
Very annoying but easily cured.
In UK we don't have that first CAT on the downpipe our part looks like this. No 7 on diagram.

There were no excessive exhaust fumes ASAFAIK.

[BTschakert]

With the flex bolts and springs the two components are pushing against each other the flex gasket is adding a dampener to the whole system. The rattle comes up when shifting or hard acceleration so the engine torques a bit and that is what was causing it in my case.

[madmanmostafa]

I actually have the same rattle. It sounds super cheap. It didn't happen at first and now after about 3K or so miles later, it even happens at idle. It just sounds like a squeak and then a rattle at around 1800RPMs. It's right there at the flex joint. However, looking at it, it didn't appear to be a flex joint. Usually flex joints.. flex?

Anyway, the flange at the springs is definitely where I can hear it coming from. I thought maybe it was the heat shield, so I pulled it off and to no avail. The noise remains.

[BTschakert]

If your bolts are in decent shape taking the two cats appart to check is fairly easy. But be warned if the are fouled up like my midwest car you will end up replacing the bolts. Mine were so bad one broke trying to get it out. I ended up die grinding it flush with the cat flang and using a vise grips on the small pice of threads left from the back side. Took about an hour to do.

[3Banger]

I just had my vehicle in. The right motor mount was gone causing shaking. I could see black debris about the right motor mount.

The gasket for my spring bolts was gone cause clanging between the pipes. I could reach down when the engine was cool, and I could move one of the springs up and down.

Mine also is a Minnesota vehicle -- for about 7-8 years. A Honda dealer drilled out the spring bolts for about $214.00. The gasket was replaced and new spring bolts were installed. The springs were still good.

The motor mount was replaced for somewhere over $200.00.