Yet another 4th gen cat rattle thread

[xxaarraa]

I searched, found several threads that complain about this problem, but none of them seemed to point to a solution that works.

Here's the story. 08 V6, 104k miles. At 900 RPM, there is a classic loose heat shield type rattle. Goes away when you rev past 900, goes away when revs fall below 900. More pronounced when transmission is in gear, i.e., stop lights.

I crawled under there several times, poked and prodded everything and none of the heat shields are loose. Yes, I checked the shields everywhere, they are all OK.

I isolated the noise to the front driver's side cat. I removed the heat shield surrounding it entirely, but noise still there. When I jam something between the cat itself and the frame cross member, noise goes away. That's partly what helped me isolate it to the cat.

Then I found this guy buzzing/vibrating like crazy (the rubber bushing).

So I put a hose clamp around it and cinched it down:

The rattle is still there, but more muted than before. It has also shifted the rattle further down in the rpm. It now happens at 600 RPM as opposed to the previous 900.

Anyone had a similar issue in the past? I am going to replace that bushing (anyone got a part #?) anyway, but could it be that my cats just vibrate more with age?

 

[jonesmw10]

I have the same issue as well. It's safe to say it's not the cat it self (internally) since the noise stops when you jam something in there to support it. I still have to take the heat shield off to see if that stops my rattle. I'll be interested to see what fixes it for you since its probably the same issue with mine.

 

[Yota_Noob]

I had a very similar problem when I bought my 4Runner roughly a month ago. At 1000rpm (no more, no less) there was a metallic rattle that I assumed was a heat shield. I work on Nissan's and they have this problem ALL the time. Finally got it in the air one day and inside those heat shields that surround the diver side cat, there was a small rock inside rattling around on the shield. There are a few really small holes in the shield I'm guessing for water to escape but not big enough to fish anything in to retrieve the rock. So I took an air blower to it until the rock shot out. No more rattle!

 

[xxaarraa]

I had a very similar problem when I bought my 4Runner roughly a month ago. At 1000rpm (no more, no less) there was a metallic rattle that assumed was a heat shield. I work on Nissan's and they have this problem ALL the time. Finally got it in the air one day and inside those heat shields that surround the diver side cat, there was a small rock inside rattling around on the shield. There are a few really small hole in the shield I'm guessing for water to escape but not big enough to fish anything to to retrieve the rock. So I took an air blower to it until the rock shot out. No more rattle!

Good point, I thought of that. But I ended up ripping off the heat shield anyway. I will however go through the other cats and try and blow some of the mud/rocks out.

 

[Combatman]

Just fixed a similar issue on my 4Runner that I just got. The PO had a Cat replaced before they sold it and there is a bracket that goes from the cat to the block with one bolt on the cat and 2 bolts on the block. Both of the bolts on the block were loose and the bracket and associated washers were rattling around. I simple tightened them up and problem solved.

Just figured that might be worth a check

 

[xxaarraa]

Just fixed a similar issue on my 4Runner that I just got. The PO had a Cat replaced before they sold it and there is a bracket that goes from the cat to the block with one bolt on the cat and 2 bolts on the block. Both of the bolts on the block were loose and the bracket and associated washers were rattling around. I simple tightened them up and problem solved.

Just figured that might be worth a check

Thanks for the tip. Any tips on how to get access to the bracket? From inside the engine compartment? Or take the skid plates off and get to it from underneath?

And just to clarify, when you say block, do you mean the engine?

 

[97BlackAckCL]

This happened to me multiple times on my 03. My buddy ended up removing the heat shields, and every time that was the cause of the rattling for me

 

[sonerick]

I had a rattle that I thought for sure was a heat shield or a cat, but it really just ended up being the gasket between the Y-pipe and the mid pipe. It had nearly disintegrated. I didn't discover this until my muffler all but disintegrated too and was replaced with a Gibson system.

The gasket is pretty cheap, might be worth looking into. If you replace it, plan on new constant tension springs too.

 

[xxaarraa]

I had a rattle that I thought for sure was a heat shield or a cat, but it really just ended up being the gasket between the Y-pipe and the mid pipe. It had nearly disintegrated. I didn't discover this until my muffler all but disintegrated too and was replaced with a Gibson system.

The gasket is pretty cheap, might be worth looking into. If you replace it, plan on new constant tension springs too.

I am going to look under there, but can you tell me roughly where the y pipe meets the mid pipe? I have the full 5 piece bud built skid plate setup so knowing exactly where to look will save a lot of time not having to take skid plates off.

 

[sonerick]

I am going to look under there, but can you tell me roughly where the y pipe meets the mid pipe? I have the full 5 piece bud built skid plate setup so knowing exactly where to look will save a lot of time not having to take skid plates off.

If you go on the passenger side, it's about 2 feet behind the front wheel and about 8" in from the frame rail. You'll see the flanged connection with constant-tension springs and bolts.

 

[xxaarraa]

If you go on the passenger side, it's about 2 feet behind the front wheel and about 8" in from the frame rail. You'll see the flanged connection with constant-tension springs and bolts.

Here's an update guys. Sonerik was kind enough to give me the part numbers for the y-pipe gasket, and I replaced it. As he predicted, my old one was almost completely destroyed.

Unfortunately for me though, my rattle still persists, even after replacing the gasket. I am back to looking elsewhere. Weirdly, the sound is more pronounced inside the cabin than outside. Super weird.

I am wondering if the issue could be more downstream - i.e., resonator or exhaust pipe itself. I know some folks just remove the resonator, and I have contemplated that, but wouldn't that increase noise in the cabin?

Resonator removed - Toyota 120 Platforms Forum

 

[sonerick]

Bummer man, sorry it didn't help.

Is the rest of the exhaust system downstream intact, i.e. not rusting out? Mine rusted at the welds between the muffler and the inlet/outlet pipes too.

There's also a heat shield above the muffler. Maybe there's something wedged in there that's rattling?

 

[Ohcrymore]

Here's an update guys. Sonerik was kind enough to give me the part numbers for the y-pipe gasket, and I replaced it. As he predicted, my old one was almost completely destroyed.

Unfortunately for me though, my rattle still persists, even after replacing the gasket. I am back to looking elsewhere. Weirdly, the sound is more pronounced inside the cabin than outside. Super weird.

I am wondering if the issue could be more downstream - i.e., resonator or exhaust pipe itself. I know some folks just remove the resonator, and I have contemplated that, but wouldn't that increase noise in the cabin?

Resonator removed - Toyota 120 Platforms Forum

Continue replacing the rest of the exhaust gaskets until it goes away. Cheap and easy fix. Had the same thing happen to me about a year ago.

 

[xxaarraa]

Continue replacing the rest of the exhaust gaskets until it goes away. Cheap and easy fix. Had the same thing happen to me about a year ago.

Yeah, makes sense. Any pointers on where the other gaskets are, and part #s if possible? Logging all the exhaust system part numbers in this thread would make it a very useful lookup for future users in the same boat.

 

[sonerick]

 

[sonerick]

Only one gasket downstream of the one you already replaced. Maybe it's that one?

 

[xxaarraa]

Only one gasket downstream of the one you already replaced. Maybe it's that one?

wow, you are awesome!

I am looking at the parts diagram you posted, and I see all these different gaskets?! All the ones I circled in red.

You think I need to replace all of 'em or just the ones downstream of the y-pipe? I'm not sure if all of them are even accessible without major work?

EDIT: Also, I'm having a hard time finding those part numbers. For 17451A for instance, is it 17451A-917-06083? What does the "**" stand for in the part number diagram? Sorry for newbie question.

 

[sonerick]

I'd start with the easy one first. The gaskets near the cats are going to be a real pain to get to. Since you said the noise is coming from somewhere near the resonator, it makes sense that this one would be the issue.

As far as parts numbers go, they are the ones in the "Part No" column. The "**" is just the website being stupid and not showing you the whole part number until you add it to your cart and place your order. I didn't realize it did this, and I'm not sure how to work around it yet.

 

[xxaarraa]

I'd start with the easy one first. The gaskets near the cats are going to be a real pain to get to. Since you said the noise is coming from somewhere near the resonator, it makes sense that this one would be the issue.

As far as parts numbers go, they are the ones in the "Part No" column. The "**" is just the website being stupid and not showing you the whole part number until you add it to your cart and place your order. I didn't realize it did this, and I'm not sure how to work around it yet.

Thanks again sonerik. I clicked through in the cart and found the part numbers, and bought them on Amazon (with prime shipping, I get it fast and also dont have to worry about creating account, putting in card number, address etc.)

I went ahead and ordered the gaskets immediately upstream (17451A) and immediately downstream (17420X) from the one I already replaced. I will report back once I fit these.

 

[hambone575]

I have the same rattle! Let me know how to fix!!!