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Hi, glad you guys are on board now as official sponsors!

I have a question about the v6 long tube headers with y-pipe.

Looking at the stock y-pipe design:

[attachmentid=16175]
[attachmentid=16176]

In the workshop diagram, it is the number 6 circle.

But looking at the CP-E design, there's only a two small flex joints that appear to hardly move:
http://www.cp-e.com/imgs/maz6s_mid_pic_01_lg.jpg

I know alot of people are complaining about ratttling, I always wondered if the fact that there is no flex in the CP-E y-pipe, when the engine bucks back and forth under hard acceleration/decelleration, is this lack of flex going to cause excessive wear and tear on the exhaust/headers/engine?

Here's several posts with current owners saying they have rattles:

http://forum.mazda6club.com/index.php?s=&a...st&p=801047
http://forum.mazda6club.com/index.php?s=&a...st&p=801106
http://forum.mazda6club.com/index.php?s=&a...st&p=801493
http://forum.mazda6club.com/index.php?s=&a...st&p=801913
http://forum.mazda6club.com/index.php?s=&a...st&p=801997
http://forum.mazda6club.com/index.php?s=&a...st&p=802213


Here's one poster who says he's y-pipe bolt broke.
http://forum.mazda6club.com/index.php?show...9468&st=15#

Any ideas on how the design of the y-pipe could be causing these rattles?
 

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Hi, glad you guys are on board now as official sponsors!

I have a question about the v6 long tube headers with y-pipe.

Looking at the stock y-pipe design:

[attachmentid=16175]
[attachmentid=16176]

In the workshop diagram, it is the number 6 circle.

But looking at the CP-E design, there's only a two small flex joints that appear to hardly move:
http://www.cp-e.com/imgs/maz6s_mid_pic_01_lg.jpg

I know alot of people are complaining about ratttling, I always wondered if the fact that there is no flex in the CP-E y-pipe, when the engine bucks back and forth under hard acceleration/decelleration, is this lack of flex going to cause excessive wear and tear on the exhaust/headers/engine?

Here's several posts with current owners saying they have rattles:

http://forum.mazda6club.com/index.php?s=&a...st&p=801047
http://forum.mazda6club.com/index.php?s=&a...st&p=801106
http://forum.mazda6club.com/index.php?s=&a...st&p=801493
http://forum.mazda6club.com/index.php?s=&a...st&p=801913
http://forum.mazda6club.com/index.php?s=&a...st&p=801997
http://forum.mazda6club.com/index.php?s=&a...st&p=802213
Here's one poster who says he's y-pipe bolt broke.
http://forum.mazda6club.com/index.php?show...9468&st=15#

Any ideas on how the design of the y-pipe could be causing these rattles?
[/b]

Thanks for the welcome! I'm sincerely sorry that you're experiencing problems with your y-pipe!

It's tough to diagnose rattles and other odd noises over the internet, but I'd be happy to guide you to help find out what may be causing these noises.

To answer your question about the flex pipe, that likely isn't the cause of the noises. The flex pipe is only there to relieve the stress induced when the engine rocks relative to the exhaust system, and to allow the pipes to expand while they heat up. We made sure the flex pipe allowed sufficient travel to prevent cracked welds and the like. Even though it is smaller than the stock unit, it should be fine even when you're hard on your car.

The rattle you're hearing is probably from the y-pipe contacting something under the car. Without looking under the car while it's on a lift, it's hard to recommend where to look for interference. If you'd like, you can take picture of the pipe under your car and send them to me, and I'll look them over with our head engineer. I can't promise anything, but we'd be happy to work with you in order to figure out what the problem is. Or, if you're in the area, you're more than welcome to schedule a time to bring your car in so we can actually put it on a lift and check it out.

I would start by jacking up the car and looking at the y-pipe to see if it gets unusually close to anything else under the car. You might also try shaking or gently banging the pipe to see if the pipe itself is rattling. Also, take note when the pipe rattles. Only when the car is cold? Only when hot? Any certain rpm range? From road imperfections? You get the point.

If you can give me some more information, we can move forward. Good luck, and I'll wait to hear from you.


Jordan
 

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I notice more rattle when the car is cold then when hot. The rattle starts around 2.5k and up until around 3k, where the sound overwhelms the rattle.

Now the rattle sounds more like the heatshield rattling or hitting something than anything. But I noticed today when it was around 80F outside the rattle subsided...a lot...after a little bit of driving.

{edit} I did jack the car up to see if a heat shield for the CAT was loose...but it was solid. I didn't want to rev the car on jack-stands...so, I didn't. I'd prefer putting it on a lift if I can get to one.
 

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I'm pretty interested in this topic too. Mine rattles pretty bad between 2250-3000 RPM, at normal throttle. If I use less throttle, it doesn't usually sound that bad. Also, it doesn't rattle at all when engine braking down through that same RPM range. All other times the headers sound really good.
 

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I notice more rattle when the car is cold then when hot. The rattle starts around 2.5k and up until around 3k, where the sound overwhelms the rattle.

Now the rattle sounds more like the heatshield rattling or hitting something than anything. But I noticed today when it was around 80F outside the rattle subsided...a lot...after a little bit of driving.

{edit} I did jack the car up to see if a heat shield for the CAT was loose...but it was solid. I didn't want to rev the car on jack-stands...so, I didn't. I'd prefer putting it on a lift if I can get to one.
[/b]

I'm pretty interested in this topic too. Mine rattles pretty bad between 2250-3000 RPM, at normal throttle. If I use less throttle, it doesn't usually sound that bad. Also, it doesn't rattle at all when engine braking down through that same RPM range. All other times the headers sound really good.
[/b]

Great, this is all good information. I have a couple suggestions.

First, try re-torquing the bolts on the flanges. Exhaust systems go through numerous thermal cycles which subsequently expands and contracts all the pipes. When this happens bolts tend to loosen up, and this creates exhaust leaks. Soemtimes an exhaust leak can sound like a metallic rattle.

Also, the fact that the rattles are less noticable when hot makes me think that when the exhaust system heats up (and expands) the flanges are pressed together and they create a better seal, which reduces leaks. I could be wrong, but this is my best guess at the moment.

If the flanges turn out to be leak-free, then I'd suggest looking at spots where the exhaust system gets close to the body of the car. Look for scratches or gouges in these areas, as they'll indicate places where there may be interference.

Let me know how it goes.


Jordan
 

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Is this happening with members who have kartboy hangers?t curious to see if the OEM hangers are part in partial responsible as well.
 

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I know I run the risk of being kicked out of the country, but I don't have the Kartboy Hangers and I do have the MF CatBack. To avoid the mufflers bumping I put some nylon around the tow bar.

Gonna check the falangies as suggested by Jordon this weekend.
 

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Rattle seems to be coming from the heatshield. I had a couple people check and there doesn't seem to be any exhaust leaks.

Bent the heatshield a little and it seems to help, but I still get a rattle.
 

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When I installed my Magnaflow Cat-Back, I noticed a rattling when I started the car. It wasn't the exhaust banging against the tow hook either because I have the Kartboy hangers. I got under the car and looked, but couldn't find anything obvious. I did howerver bend the heat shields so they didn't curve at the bottom. I did this most of the way along the exhaust. That eliminated the rattle. Might be worth trying. No idea what kind of rattles I will get when I finally install my headers though...
 

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When I installed my Magnaflow Cat-Back, I noticed a rattling when I started the car. It wasn't the exhaust banging against the tow hook either because I have the Kartboy hangers. I got under the car and looked, but couldn't find anything obvious. I did howerver bend the heat shields so they didn't curve at the bottom. I did this most of the way along the exhaust. That eliminated the rattle. Might be worth trying. No idea what kind of rattles I will get when I finally install my headers though...
[/b]

Did that for the front part. The exhaust is such a low rumble with the headesr and magflows. Sounds great, but looks like it's resonating with the shield. I'll try that once I get back to the West Coast.

One of the guys I talked to suggested some foam backing on the backside of the heatshield. Maybe later.

Thanks!
 

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I took my car to a shop and had them fix any exhaust leaks, and they fixed two of them. The rattling/buzzing was definitely reduced. Which part of the heatshield are you guys bending?
[/b]
I believe people are bending the very bottom of the heat shields. You will notice at the edge, it's contoured to follow the bottom of the car. Try bending the shield so it is straight.

Great, this is all good information. I have a couple suggestions.

First, try re-torquing the bolts on the flanges. Exhaust systems go through numerous thermal cycles which subsequently expands and contracts all the pipes. When this happens bolts tend to loosen up, and this creates exhaust leaks. Soemtimes an exhaust leak can sound like a metallic rattle.

Also, the fact that the rattles are less noticable when hot makes me think that when the exhaust system heats up (and expands) the flanges are pressed together and they create a better seal, which reduces leaks. I could be wrong, but this is my best guess at the moment.

If the flanges turn out to be leak-free, then I'd suggest looking at spots where the exhaust system gets close to the body of the car. Look for scratches or gouges in these areas, as they'll indicate places where there may be interference.

Let me know how it goes.
Jordan
[/b]
Jordan,

Did you guys test the y-pipes that were fixed by Kooks? I know the original y-pipes were tested as part of the original design, but I'm interested to know if CP-E had the opportunity to test the fixed pipes with the headers.

There still seems to be a lot of people having issues with rattles even after double checking for leaks and verifying that nothing is in contact with other parts of the car. The more people try to figure out what the rattling is, the more it seems like it's coming from the y-pipe/cats.

A few people have even mention that they had no rattling with the original y-pipe (until the cats failed anyway) or with the off-road one.

Just curious what input you might have on this.

Thanks.
 

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I believe people are bending the very bottom of the heat shields. You will notice at the edge, it's contoured to follow the bottom of the car. Try bending the shield so it is straight.
Jordan,

Did you guys test the y-pipes that were fixed by Kooks? I know the original y-pipes were tested as part of the original design, but I'm interested to know if CP-E had the opportunity to test the fixed pipes with the headers.

There still seems to be a lot of people having issues with rattles even after double checking for leaks and verifying that nothing is in contact with other parts of the car. The more people try to figure out what the rattling is, the more it seems like it's coming from the y-pipe/cats.

A few people have even mention that they had no rattling with the original y-pipe (until the cats failed anyway) or with the off-road one.

Just curious what input you might have on this.

Thanks.
[/b]

We tested the y-pipe after the Kooks fix, but we didn't encounter any unexpected noises. I'm wondering now if this is an isolated incident with several of the kits, or if everyone is having rattle issues? Anyway, here's another couple procedures we'd like someone to try.

Since people claim the rattle is coming from the cats, our first shot in the dark would be to wrap two or three stainless hose clamps around the cats. This should help hold the heat shield around the cat, and will keep things from vibrating if there's any play. The other thing someone might try is to hold your hand on the cat and feel for any vibration (while the exhaust is cool of course!). If you feel a vibration at the same frequency as the rattling sound, then this would also help determine what the heck is going on.

Josh told me this afternoon that we're going to have a 6S coming in soon, so we'll be able to play with it some and see if we can't figure out what the cause of the vibration is. Thanks a lot for your patience guys, and I'll keep you updated once we get the 6S in here.

By the way, is this noise everyone is hearing a 'buzzing sound', or a 'rattle?'


Thanks,
Jordan
 

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I'm getting a buzzing sound
[/b]

If that's the case, I have a feeling the cat heat shields are vibrating and the hose clamps could be a temporary fix. If someone has a chance this weekend, give that a shot and see if that helps.


Jordan
 

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You're talking about putting clamps around the whole cat itself to hold the two halves together?
[/b]

That's my thinking, yes. I was imagining stringing a few clamps like these together:



I'm pretty sure the halves are stamped together and then tacked, which leaves room for the shields to flex away from each other away from the tacked areas. If that's what's causing the buzzing/rattling, then hose clamps around the outside of the cat would help press the shield halves together and maybe reduce or even stop the buzzing. Then, we can work on a proper fix for you guys.


Jordan
 

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Ill see if i can take a run to home depot and get some of these and try it out for you guys. I never had the rattle with the offroad y pipe i had but now with the kooks modified y pipe im getting the rattle sounds like your taking a wrench and hitting a thin sheet of metal. I did rev the car and it does sound like its coming from the cats.. From what i heard.. I did check for leaks while the car was on i put my hand around all the flanges and didnt feel any air coming from them.
 
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