ancdmd

what kind of noise are you getting at 60mph?

BMW7_LS430

Is there something to protect cats from getting to this problem? Like a spray or something that prevents rust.

peafarmer

The noise is sort of like the noise that you hear from one of those subarus with the "racing" exhaust pipes. It is pretty quiet at idle, but not lexus quiet. At low speeds in a parking lot it seems "normal". But when driving, it passes through two resonances at around 35 mph and 60-65 mph. Of course, these are the two speeds that you really don't want the noise. The really crazy thing is if I speed up to 75-80, it seems much quieter, don't know if the wind noise is eclipsing it or if it really is quieter.

I am going to crawl under the car today and see if I can hear anything at idle...I wish I had a super direction-finding sonar system to pinpoint the noise, because the noise is not too bad at idle....

Thanks,
Andy

BT3100

Another good way to tell if you have a leak is to open your window when you are in a fast food drive through.
You will hear the sound loud as the wall on the drivers side will resonate the sound.

peafarmer

OK, crawled under the car today to change oil and take a look. What I found is that the gap on the flanges between the upstream cats and the Y pipes is much wider at the bottom. The driver's side is actually leaking water when the car is started. Also, I was able to sense the leak using a piece of newspaper.

The gap is close to 1/4 inch on the lower flange side and less than 1/16 inch on the upper flange side. The driver's side was also tighter on the left side than the right.

So, I took some 14mm wrenches and evened the driver's side flange from left to right, but there is no way to even it top to bottom.

So, either the Y pipe needs to be bent upwards a few more degrees, or, ....is there a gasket type that can make up the misalignment. I can't imagine that exhaust systems are that precisely bent, but who knows.

If the Y pipes need to be bent more, should I just return them and buy the Lexus part, or can a good shop tweak them to make them mate up nicely?

Thanks,
Andy

BT3100

Hey Andy I know the feeling. Those flanges need to be leak proof or you will get a P430 or P420 Code and a Check Engine light. The gasket that goes between the pipes is 1/8" thin and has a metal surround. It is not forgiving and will not take up much slack. To make matters worse if you try to replace the gasket without pulling the "Y" pipe the gasket tends to get torn up by the lip inside the flanges.
Here is what I did and it worked. Once the surfaces were mated I felt for leaks. Any leaks must be sealed. The bottom side in my car had about a 1/16" gap. I used Quick Steel High Temp to seal the gap. This resin works great for larger gaps but must be left to cure for 24 hours. For the thinner gaps I used Acousti/Seal. This is a great product for sealing minor voids in the exhaust system. It may be able to seal larger gaps but I used the Quick Steel. Acousti Seal has been used for decades by shops to ensure a leak free seal when joining pipes. It is a great product that cures as you drive.

Here is a link...

http://www.turnermotorsport.com/p-13...-5oz-tube.aspx

ancdmd

also make sure you use lexus gaskets, the ones that come with the y-pipe are junk.

Lavrishevo

iTrader: (1)

Check out my experience with my LS400:

https://www.clublexus.com/forums/ls4...r-lessons.html

peafarmer

OK, took it to a custom exhaust shop with a good reputation today and they re-aligned the Y-pipe and then were able to make the flanges fit. Also, they found that the pipe was out of round at the rear, just in front of the resonators, so they welded it there. Now the exhaust is quiet.

Only problem...car is still making noise...now it looks like a have a bad wheel bearing. No wonder the thing was so loud, both bearing noise and exhaust at the same time. Off to another thread!

Andy

Boomer01

Is the code gone?

Kira X

iTrader: (24)

Thanks for that link. I never knew about all of that stuff. My muffler guy mentioned that some Lexus' will throw codes with a high flow cat.

acarapella

Did anyone have long term luck with an aftermarket pipe and cat? My es300 y pipe / flex pip / cat unit is leaking. A new from Lexus is $1,300. eBay aftermarket is $250. But I haven't heard good reviews. Still looking at my options and getting opinions

ancdmd

I've had mine for 18 months and its fine. I got mine from the Exhaust Distribution website, but they also sell on ebay. I just installed Magnaflow cats last week, they seem well-made and are stainless steel, not sure about the core material, so hopefully they will last quite a while.

acarapella

What kind of car do you have

ancdmd

I have a 2002 LS430