Auris II | Cat. Converter Insulator Vibrating

[Auris GTI]

Hello!

Under light load and/or low rpm's the exhaust of my 2013 Auris HSD makes a 'tin canny' sound. Engine has to be at working temperature.
Booked it in to check with a mechanic (while throttling in P) and it was coming from the catalytic converter insulator (heat shield).

I was wondering if anybody else had this problem?

The insulator is connected to the (cat.) exhaust pipe with two rigid bolt connections, and two bolts with some kind of flexible washer (to deal with thermal expansion?).
(Re)tightening the bolts fixes the rattling for about 1-2 weeks. Would it be possible for these rings to wear out (10+ years) and unable to keep the connection under tension?

Looking at the spare parts manual, these rings are only delivered with the heat shield itself (PartNo. 17551-37040) which would probably be a pricier repair.
Is it really necessary for this connection to be flexible? Otherwise I could try to make all connections rigid to see if this works as a long term fix.

Thank you!

[Bper]

Hi John,If you fix the catalytic converter heat shield without a washer, you risk potential problems. The main issue would be a significant increase in rattling and noise coming from the exhaust system. The washers act as a buffer, absorbing vibrations that would otherwise cause the heat shield to bang against the exhaust pipe. Without the washers, these vibrations would be directly transmitted, creating a constant and likely louder tin can sound.The continuous rattling and contact between the heat shield and exhaust pipe could damage both components. Over time, the vibrations could wear down the metal of the heat shield and exhaust pipe, leading to holes or cracks.

As mentioned earlier, the washers also help accommodate thermal expansion. Without them, the connection between the heat shield and exhaust pipe becomes more rigid. This rigidity could cause stress on the exhaust components as the system heats up and cools down during operation. In extreme cases, this stress could lead to cracked. Hope this helps.

[TonyHSD]

I never seen on any hybrid these to go wrong. Usually every single Toyota will get similarly rattling noises but from any other heat shielding along the exhaust pipes. The reason is corroded material and holes becomes bigger so bolts and washer not able to hold the detail in place. Placing larger washers including cola cans can fix it as good as new. If you are definitely sure the rattling is from cat shield and these social washers are to be blamed, look from what they were made and do something similar as diy. The cat gets very hot, something to have in mind . 

[Auris GTI]

Thanks for the responses. Guess no washer is a big nono, makes sense.

Tony, I did a lot of searching and agree that almost all threads are about heat shields connected to the body. But I am absolutely positive that the cat. insulator is the problem here.

Searching for the CT200h gave me a hit though and replacing these rings was also mentioned. There was no follow-up after replacement unfortunately..

 

 

[Auris GTI]

I did some more digging on this problem with Toyota Prius searches and found some interesting information and similar cases.

These washers are a single standoff made from a seamed material, and the wire mesh is basically acting as a spring to prevent it from rattling. It is non-removable! 

I found some videos of the exhaust manifold heat shield (of a Toyota Prius), which uses the same standoffs, where the mesh is worn which allows the shield to rattle. This could also be a possibility for the problem with my catalytic converter heat shield. 

Does anybody know if the catalytic converter heat shield is accessible to remove, without removing/lowering the exhaust assembly?

https://www.youtube.com/watch?v=0sTKU20ZT-A

https://www.youtube.com/watch?v=oF3ykE-UNNk

[TonyHSD]

These videos are helpful. Not sure if you can remove the heat shields without lowering the exhaust. , best you can do is to try yourself. Also if you stuck a new wire mesh or something between the washer and heat shield to stop from rattling you will be good to go and not need to replace the whole part. 
Good luck and let us know how you did. It will be helpful for others. 👍

[Auris GTI]

And now for the conclusion because I hate unresolved threads...

Heat shield on top of the catalytic converter has been replaced some time ago. I've driven over 1500 miles with it and no rattles at all. Pretty sure the bushings were the problem. An audio file has been attached for future reference.