Car is a 2005 LS430 with 212k with original cats.

Issue: The catalytic converter flange is rusted and deteriorating away causing a leak between the flange to the Y-pipe.
See photos below. I also put up a photo of the "good side" to see the difference in appearance.

Has anyone run into this?
Do they make flanges that could be welded onto the original cat?
If not, what mfg are you guys replacing cats with? Bosal? Walker? Pacesetter? etc?

Thanks in advance!

 

I'm not sure there is much you can do with this. In general, exhaust rust occur from the inside out, although the external part looks rusted out. I've seen very few car exhausts over the last 50+ years where rust is from the outside in. Exhaust gases carry a lot of moisture/condensation, so no matter how much you try to protect the outside, you still can't manage the inside rusting problem.

I've seen some welders fabricate these parts, just the rusted out area, cut out the rusted section, and weld a new one in. but that only buys you a couple of years. I wish there was hope i could offer you. maybe someone here knows more about this?

 

All valid points, thanks.

Looking like I will go the replacement route. OEM prices are super expensive, so I will go aftermarket.
All ears to others experiences and recommendations on aftermarket items, good or bad.
Thanks.

 

There are many many many threads regarding this infamous Y-pipe. I think you're lucky to have gotten that many miles out of yours. Mine rusted through at various areas, including where you show on your picture. I had about 150k miles on it. I believe I got a good deal on Ebay and paid about $625 which included shipping. The cat flange is very thick and when we removed the rusted pipe, the flange was solid and easily mated up to the new Y-pipe.

Here's a link to the Ebay listing... Y-Pipe linky to Ebay

The part # is 17410-50390 for 2004-2006 model years.

 

Thanks. Thats not a bad price for the OEM y-pipe.
I am more concerned about the Cat side flange. it appears to be worn pretty well.
Does anyone have a up close photo of the cat flange? Curious what the mating/sealing surface looks like.

 

Google the part number, 1845050350, plenty pics of similar cats/flanges.
Here's the actual part...

 

If you can find a shop that specializes in exhaust repair they can do repairs @ about 1third of the cost. I have a local one I send friends to and any exhaust prices are about 1/3 of the quotes they have gotten from auto repair shops and dealers. Good Luck

 

Thanks guys

 

Local shop with aftermarket part with lifetime warranty - $640 installed w/tax.

 

If I were in your spot, I'd get the Pacesetter Y pipe from Rockauto. It has a heart next to it too, which means many people have bought it and there have been very few issues/returns. Less than $200.



Yea, it's nice to have OEM but for this I wouldn't bother. You can buy three of these for the price of the Lexus part.

 

Since no one mentioned it yet, I would like to point out that you really need to use OEM gaskets for all flanges. The ones that come with these aftermarket parts are apparently not very good. Even my local no-name shop, who has since gone out of business, knew this and ordered me OEM gaskets when ordering my aftermarket Y-pipe.

 

Thanks Stan!
I have new gaskets on hand. Going to separate the Y-pipe from the cat and see how the flanges looks once exposed.
To be continued....

 

Anyone know why they took this off of Rockauto. Debating on whether this or Davinco is the better fit.

 

The new OEM gasket did the trick.
The old one had deteriorated and was causing the issue.
Its been 3-4 weeks with no issues.

 

Many of us live in CARB states, though, and have annual emissions inspections....