Rattle under car: Heat Shield corrosion
 

I had this strange rattle noise coming from under my 8 when releasing clutch and hitting around 3000rpm. At first I though it was just some loose screw somewhere.

Took it to dealer and was told (and shown) the nightmare: the heat shield around exhaust/cat was all rusted and had practically been corroded into two pieces.

The dealer quoted 3.5K for repair, apparently they want me to replace the whole exhaust/cat system. I was 5 months out of rust warranty, called MNAO and no go, quoting that there is nothing wrong with the car, it is the salt on the road to blame...WTF, I have been doing my oil change and maintenance at the dealer since I got the car, and no one ever informed me that there is rust there...so much for the "360 full cycle check"....

Is there anything else I can do to get rid of this noise without replacing the whole exhaust/cat? There is nothing wrong with exhaust/cat, just that the external heat shield is corroded. Can I just replace the heat shield?

Any thoughts?

Thanks all.

have you tried going to a local exhaust shop for some recommendations? Not sure if you posted a pic as my work may have blocked it, so I cannot see the damage.

This is a VERY common occurrence. The crazy heat makes them rust.

VERY simple fix: go to home depot and buy two large (maybe 1-inch wide?) hose clamps, at least 18 inches long.

Make sure the engine and exhaust are COLD - the car should be off for at least 2 hours. Jack up one side, and use 2 jack stands for safety. Wrap each hose clamp around the heat shield and the piping all together, one towards each end of the shield, and tighten them down really tight. The shield will still work effectively, and it will no longer rattle.

I've done this fix on my rx8, and a friend's miata. Works like a charm. It won't last forever, but certainly for another 10,000 - 20,000 miles. Then you can just do it again if needed.

yeah that 360 check is bullshit.

it's also bullshit that they want you to pay $3k for a replacement cat, when then catalytic converter itself the expensive part) is fine. They just suggest that because there's no way for them to replace only the shield.

Depending on what has corroded you can fix it differently. If it is just the hole around the bolt...a big washer will work...otherwise there are strip clamps or even wire that you can use..

Dealers have limited options to jury-rig things like DIY or muffler shops can

FWIW, during a routine inspection, the dealer told me that they needed to replace (repair?) my heat shield and bolts.

They did it for $165.

No idea what they actually replaced though.

EDIT: It did involve ordering parts, if that's any clue to what they did

I forgot what the heatshield look like, haven't really look underneath for a while :)

is it in the picture? if it is, you can buy it.

https://www.rx8club.com/attachment.p...1&d=1339027636

Do you still have the repair record? What is the part number for the heat shield?

If you can find the part number I can run a quote with the dealer again. Or I will just go with the DIY solution suggested above.

Yeah, I got rattle too. Mine isn't from the heat shield tho lol's.

http://youtu.be/vxSspNwlfRk

If yours is only partway off you can just use a hose clamp to hold it back on as everyone else said.

Here is pictures of what mine looked like before and after

https://www.rx8club.com/showthread.p...3A+Heat+Shield

Thanks all! Looks like hose clamp is the way to go. I managed to took some pictures, and the situation looks pretty similar to yours.


Could you please let me know if anything else looks bad (other than the heat shield)?

I hate diagrams, they look complicated...yes they are. lol

its all in one piece u can't buy another one from Mazda and slap it on.
well, there are alternatives, u just need to have some creativity that's all

Nope just looks like the heatshield. Good luck with your repair!

Mine rusted off about 6 months ago and I never replaced it. Should I replace it?

Peekaboooo Just don't park on any tall dead grass and you should be fine. I think a guy on these forums did drive over a garbage bag blowing in the road and it got stuck to his cat and caught on fire. (don't remember if that was this forum or another)

Just be careful and you will be fine. If you still have the shield Peekaboo you can always reattach it with those hose clamp method. Or using a old metal close hanger.

I had a similar issue. The dealership simply removed it. Said it wash't really required.

Thanks for the advice Gopherage. When this heatshield was rattling I was quite worried about it, and then one day it just fell off. I do have a new upper and lower shield, but I never put it on, I think I'll put it on now after hearing about the hazard.

Our Infiniti had a similar problem. I ripped off the shields also. I notice a significant increase in cabin heat and I could even feel it from the exterior coming through the windows at a stop. I used the hose clamp method to put it back.


I can't imagine how noticeable the heat increase would be with our 1700*F EGT... It's already horrid with the heatshield.

Did you say that you need an 18" hose clamp? I can only find 16" ones at the most. Where are you finding these large hose clamps?

Undo them, connect end to end for an infinite length of clampage....

Alright cool. Thanks

This. Just tighten the hose clamps if it rattles again.

Help me ben
 

hey ben i know its been almost 10 years but i had the same exact sound on my rx8 whenever i speedup around 2-3k rpm would you remember how you fixed it or what the problem was and if it was that bad? Thanks.