08 LS Flex Pipe Replacement Suggestions

[dakotart1984]

Just started getting the P2096 code and I saw a few threads posted but im looking to see if anyone has had any recent experience with replacing their flex pipe. Im looking to replace the entire pipe not just weld in the flex and I have a few questions. Will the walker part (54785) suffice or should I save more beans and opt for the OEM? Once I get the pipe off, is there a replacement screw/bolt that one could recommend? As it looks, those bolts arent going to make it off without disintegrating completely. The cat appears to be fine. Also what fel-pro/walker part numbers are needed for both ends of the pipe?

[avguy]

You didn't say if you definitely found a leak in the pipe. If not, the O2 sensor would be your first suspect.
I used a Walker muffler on my '05, and it was a perfect, drop-in fit. They obviously spent some time doing it right, because with 3 hangers and the flange, there's not much room for error in building this part. You should be able to figure out all of the parts you need from Rockauto or one of the other parts sites.
If you do go ahead with replacing that pipe, study the whole thing carefully. On my '05 there is no way the flex pipe connection to the cat would come off clean. Due to the really poor design of the cat flange, the new flex pipe would either need to be welded to the cat flange, or else I would need to buy a new cat. And also take a look at the type of bolt being used. It may have changed by 2008, but on my '05 they used miserable flange-welded bolts. These wretched bolts are always totally un-reusable due to rust. But far worse, they also don't just drop out either - they need to be drilled out. From my DIY point of view, it's the worst possible type of fastener that could be used for exhaust parts, and made the muffler replacement take much longer than it it should have. I guess they just figure this work will be done by someone working under a lift with specialized professional tools and welding equipment. If you don't have that stuff, plan on a long day.

[petrified.rabbit]

the second o2 sensor is in front of the flex pipe anyhow. So only replace it if it is leaking. The Code is most likely the o2. as it would still read correctly since it is before the leak.

i didn't look at the exhaust parts.

[dakotart1984]

You didn't say if you definitely found a leak in the pipe. If not, the O2 sensor would be your first suspect.
I used a Walker muffler on my '05, and it was a perfect, drop-in fit. They obviously spent some time doing it right, because with 3 hangers and the flange, there's not much room for error in building this part. You should be able to figure out all of the parts you need from Rockauto or one of the other parts sites.
If you do go ahead with replacing that pipe, study the whole thing carefully. On my '05 there is no way the flex pipe connection to the cat would come off clean. Due to the really poor design of the cat flange, the new flex pipe would either need to be welded to the cat flange, or else I would need to buy a new cat. And also take a look at the type of bolt being used. It may have changed by 2008, but on my '05 they used miserable flange-welded bolts. These wretched bolts are always totally un-reusable due to rust. But far worse, they also don't just drop out either - they need to be drilled out. From my DIY point of view, it's the worst possible type of fastener that could be used for exhaust parts, and made the muffler replacement take much longer than it it should have. I guess they just figure this work will be done by someone working under a lift with specialized professional tools and welding equipment. If you don't have that stuff, plan on a long day.

Thanks for the replies. I havent taken the O2 off to check it yet but I can literally separate the flex portion of the downpipe that comes from the cat. I jammed the pipe back in, cleared the code and it took 2 days to come back on, rather than coming back after 15 mins of driving after clearing it. Thats why im suspect that the flex could be the cause and it definitely has the hum of an exhaust leak. I figure, replace the pipe as its needed anyways then look at the O2. Im not ruling out that the O2 or the harness could be bad yet as I cant count how many times Ive smacked that thing while working under the hood. I wont have time until next week to look at it. The one tool I dont have is a welder, I have access to one but I REALLY dont want to have to weld anything. I would rather drill out the bolts and replace them with proper ones that can withstand the test of time, hence why I was asking for suggestions for hardware.