OK, I searched and searched and searched on this topic to no avail. With that said:

I got under the car to check it out yesterday. Shook the entire exhaust, from the exhaust manifold to the cat to the b-pipe to the muffler. Even pinged on it with a hammer here and there. The rattle was sourced at the b-pipe, NOT the cat converter. Upon shaking the pipe a bit more, I noticed a few "pebbles" that were poking through the (I think there's two) holes on the bottom of the b-pipe. There was a white one and a pinkish one. I'm 90% sure that these things are what's rattling, as the sound it made when I was shaking the pipe sounds virtually the same as when the car is running. FYI, the car has ~145000 miles and is stock. There have notbeen any CEL codes thrown my way (yet). The heat shields are firmly fixed to the car, and there was no contact between exhaust components and the shields even with some vigorous shaking.

Before taking further action, I wanted to ask what is a good way to go about dealing with this problem. I've concluded that I have to remove the cat and b-pipe to get a better look at the "pebbles".

1. Do you guys think the "pebbles" are broken off parts of the catalyst's element (what else could they be)?
2. If the old cat is bad, should I get another OEM cat? From what I can tell, they're really expensive (~$700). If not OEM, can you suggest a good aftermarket? I've heard that a lot of the aftermarket ones go bad fairly quickly.
3. How the hell do you get the rusted bolts off the exhaust components?

Thanks in advance.

 

i think i have t he same problem....does it happen all the time when u drive cause when i drive my car it only happens once in a while. Sometimes when its at idle it makes the rattle noise till i reach 2500rpm and then its gone. the cat convertor i prefer is Catco...its only $100.

 

It becomes noticable when the engine is at either 1100 RPM or greater than 3000 RPM. I can still faintly hear rattling at all other engine speeds. Catco? Never heard of it. Can you give me more details: how to get it, how long have you had yours (assuming you have one), fitment issues, etc. THanks!

 

no i dont have a catco cat convertor, but ive heard it performs very well. U can find it at Jegs.com.

 

not sure what 'pebbles' you're referring to in 1, but you might want to check your heatshields. if gravel gets caught in them they can rattle and sound awful. As for cats, carsound (aka magnaflow) is a great brand catalytic converter to look into. Flows much better than stock or catco, only drawback is that they come in universal sizes, so you would have to get the flanges welded on by muffler/exhaust shop. For rusted bolts, go to any auto parts store and look for "PB Blaster". Spray it, let it soak 10-15 min (some people even wait overnight) and attack! That stuff works wonders.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by MugenGSRb18 &raquo;</TD></TR><TR><TD CLASS="quote">no i dont have a catco cat convertor, but ive heard it performs very well. U can find it at Jegs.com.</TD></TR></TABLE>
NO WAY. Go to summitracing.com We don't sell magnaflow. But we do have dynatech and catco. I think the dynatechs are all high flow, and catco has those EPA and highflow ones. We also carry a few other off brands. And I believe we can get some drect fit highflows as well for some hondas. I've had a catco on my car for about 4 years and haven't had any problems with it. I have a universal 2 1/2 inch that the muffler shop welded the flanges and o2 bumg on for me.

 

i'm having the same exact problem... i'm just everything is rusted on the bottom so i can't just take out the cat to check it out.... soo i'm probably just going to change the whole piping system along with the cat.... good idea? we'll find out soon enough

 

[<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by mdpalmer &raquo;</TD></TR><TR><TD CLASS="quote">.
3. How the hell do you get the rusted bolts off the exhaust components?

Thanks in advance. </TD></TR></TABLE>

pb blaster 10-15 minutes done also try craftsman damagedbolt nut removers there is nothing that combo will not get off

 

You might just wanna get new bolts for the exhaust so you don't have to worry about having the same trouble down the road.

Breaker bars works good for snapping the bolts.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by FlatBlackTeg &raquo;</TD></TR><TR><TD CLASS="quote">You might just wanna get new bolts for the exhaust so you don't have to worry about having the same trouble down the road.

Breaker bars works good for snapping the bolts.</TD></TR></TABLE>

Yep, that was exactly what I was thinking!

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by dFreezy &raquo;</TD></TR><TR><TD CLASS="quote">not sure what 'pebbles' you're referring to in 1, but you might want to check your heatshields. if gravel gets caught in them they can rattle and sound awful. As for cats, carsound (aka magnaflow) is a great brand catalytic converter to look into. Flows much better than stock or catco, only drawback is that they come in universal sizes, so you would have to get the flanges welded on by muffler/exhaust shop. For rusted bolts, go to any auto parts store and look for "PB Blaster". Spray it, let it soak 10-15 min (some people even wait overnight) and attack! That stuff works wonders.</TD></TR></TABLE>

I'll get under the car later next week and take some photos for you. Time for a stupid question: what does "PB" stand for in "PB Blaster"? I see you're at Virginia Tech. One of my former TAs did his undergraduate work there. What year/major are you?

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by seejay &raquo;</TD></TR><TR><TD CLASS="quote">i'm having the same exact problem... i'm just everything is rusted on the bottom so i can't just take out the cat to check it out.... soo i'm probably just going to change the whole piping system along with the cat.... good idea? we'll find out soon enough
</TD></TR></TABLE>

That may be expensive, depending on where you get your parts. I was considering doing that, but didn't have much of a reason to. Everything else looks good except for the rusted bolts and pebble things in my b-pipe. What I'll probably end up doing is:

1. remove the cat, examine it. replace if need be
2. remove the exhaust pipe B and shake out the pebbles
3. double check heat sheild fitment
4. get new bolts/fasteners/gaskets
5. bolt everything back up

It sounds like if I get an aftermarket cat, there has to be some welding done in order to get it to fit correctly. I'll research this a bit more.

 

OK guys, I fixed my rattle noise that EVERYONE seems to talk about. I had this rattle noise on my '94 GSR and I fixed it in my '95 GSR. So here it is.

On another thread I read that the rattling comes from the A pipe aka downpipe from the exhaust manifold (headers). I pulled everything off and inspected the downpipe and if you look at the entire stock headers it's really big in diameter but when you look inside the tubes it's not so big. Basically there's a pipe inside the cast iron molding (pipe within a pipe) and what happens is, it breaks off from the outter cast iron piece. Then when you rev to 3,000rpm it will rattle.

I put in some DC 4-2-1 headers and it fixed the problem instantaneously. Of course on other cars there may be other sources for the problem such as heatshield. Just check everything, but the really loud annoying one is usually the stock headers.

 

Well, I got under the car and had one last look.

I realized that there are heat sheilds that sit on the underside of the cat and exhaust pipe B. For some stupid reason, I thought that they didn't exist before. Well, I also realized that there is some space between the shield and pipe where small objects, like pebbles, could get caught.

You guys already know what happened: I ripped the damn thing off (of pipe B), and guess what? Pebbles galore!!! I think that four or five 4-5 mm diameter pebbles fell out with the shield.

I was so excited about this, when I started my car back up, I ripped around the block to check that the sound was gone. It turns out that the 1100 RPM (almost idling) is totally gone. Unfortunately, the &gt;3000 RPM rattle is still there. I suspect that there may be some other pebbles stuck in the shield under the cat. I'll try taking that thing off tomorrow.

BTW: those rusted bolts gave me hell!! even with the PB blaster!

 

nice.. I have the same *** problem on my 94
gsr...guess I need to get under and check

 

check those rubber pieces. maybe one came lose

 

That rattle is most likely your upper heat shield. The corners tend to rust, resulting in an unsupported, vibrating structure.

 

Your hypothesis is probably correct, assuming that the rust has caused some deterioration of the bolts/support. For my car, I don't think the rust has done that much damage yet. After examining the bolts/nuts/supports, I think that they may have be even stiffer due to the bonding effect the rust has on the fasteners. But it is consistent with the vibration at higher engine speeds (stiffer =&gt; higher frequency) When I get the sheilds off I'll let you know.

 

ive done all of the above... my car still rattles. i took out my whole cat off the car and took off the heat shield to see if there was any pebbles. i got aftermarket header alrdy. everyone ive asked in the past juss say its the heatshield... either its rubbin or like wat Dogginator said... its rust.