Muffler clogged?

[terryjm1]

When you buy a vehicle that was left in a pasture and worked on by high school auto shop students it is reasonable to run into some odd problems. I think this is an odd one. Well, I haven’t seen this before.

Yesterday, on a 16 mile up hill drive my exhaust started sounding odd. It got a little louder and sounded like exhaust was leaking but still muffled, more like air escaping under high pressure. It’s hard to describe but it is not like a typical loud exhaust leak. And the sound goes mostly away when not under hard acceleration. It’s definitely coming from the tail pipe. I can hear just a bit of the odd noise at idle listening close by the tail pipe.

This one has a Borla center muffler and the rear one has been deleted with a short section of pipe replacing it. It wasnt loud and had a nice low rumble before it started making this odd sound. What is also nice is the tail pipe, without the rear muffler, is the perfect fit for the SG bumper keeping it up and out of the way.

I believe the Borla has fiberglass in it and I think it has shifted causing this noise. I also think I’m down on power a bit, likely caused by a partial restriction. It also rattles when I shake it. However, I can’t completely rule out it isn’t a catalytic converter rattle. Being the hoarder I am, I have a replacement exhaust ready to install but I am bummed because the current exhaust is solid otherwise. My suspicion is moisture has rotted away the metal inside allowing the fiberglass to move and cause a partial obstruction. The Borla appears to have a stainless steel shell but I imagine that is not the case inside. I have an endoscope. Maybe I will take a look through the tailpipe.

Anyone experience a muffler failure like this?

 

[kris812]

My Center muffler did something similar on me. It was already replaced by the P/O along with 1 Cat.

Whenever I had the cat Y pipe off, I ran compressed air into the OUTPUT of the Y pipe and listened to the 2 inputs. The Cat that was replaced was definitely 50% restricted. Got a new Y pipe from Partsgeek.

Much later my center muffler started rattling and making weird noises. Only 99% sure that was the problem, I hit the center muffler with a big hammer and dented it in, the noise went away so then I was 100% sure.

I went with flowmaster so that there wasn't any stuff inside to go bad, and I've used them for decades without any issues like this. I also went this route because the factory pipe hits the rear A arm on Droop.

A Local shop charged 300$ for cat back pipping with muffler, britpart pipe kit was 300$ as well and reviews said it needed tweaking.

 

[JUKE179r]

This D2 muffler was clogged too

 

[StangGT5]

I have not seen a muffler fail in a way that it caused a restriction. However, I have absolutely seen the old D1/RRC Land Rover catalytic converters break apart and get blown all the way into the rear muffler. I've heard cheap replacement y-pipe rattle like the stock ones, but not break apart and clog the system like the stock ones do.

Is it possible you're hearing catalytic converter material in the borla muffler, rather than the innards of the muffler itself? Assuming the y-pipe connection was retained, maybe disconnect the muffler from the y-pipe and take a look inside.

 

[terryjm1]

“Is it possible you're hearing catalytic converter material in the borla muffler, rather than the innards of the muffler itself?”

I have considered that may be the issue but hope it isn’t. I’m not getting any “catalyst inefficiency” codes. I will hook up my diagnostic scanner and see if the O2 sensor readings are weird until I can get a look inside.

One of the cats has a decent size dent in it…

“Assuming the y-pipe connection was retained, maybe disconnect the muffler from the y-pipe and take a look inside.”

i will be prepared when I get it on the lift to replace everything if needed.

To add to the worldwide contribution from forum members to this D1, I picked up a lightly used Y-pipe/cats and muffler from lunchbox in St. Louis my last visit.

Unfortunately, I had to move a bunch of stuff into my shop temporarily from our house and have to wait until I get that out of the way before I can tear into the exhaust issue.

Sigh, my 300tdi D1 is sidelined with a wheel bearing issue and now this one is sidelined with this issue. Both happened shortly after I moved all that stuff to my shop.

 

[terryjm1]

I finally had a chance to investigate the problem. It was both a catalytic converter that came apart internally as well as the muffler. I only found two chunks of the catalyst material stuck in the muffler but much more must have passed out the tailpipe. The entire last section of the catalyst material was gone. Also, a piece of the muffler internals had lodged at the back of the muffler and prevented the larger chunks from passing through. I’m going to guess the catalyst material damaged the muffler.

So, I pulled the entire exhaust and replaced it. I used a Britpart center muffler and an ansa rear pipe and resonator. The new y-pipe and converter came from Atlantic British via Lunchbox who sold it to me after briefly being on his D1. He also gave me the lightly used center muffler.

One lesson learned… don’t mix Britpart and Ansa parts. I had to shorten both the Ansa pipe and Britpart muffler exit pipe as well as do a lot of bending to get it all happy together.

By the way, the standard rear resonator doesnt fit well with the Safari Gard bumper. I may end up cutting off the resonator and fitting a short section of pipe. It just hangs down too much and kind of defeats the purpose of the Safari Gard high clearance bumper. Why do they make those resonators so big?

It does run super quiet now. The loudest noise it makes is the very overactive fan clutch.

 

[terryjm1]

Following up on this, i received a quote to sell the catalytic converters from RRCATS today. They are half the value they were about a year ago.

But, that is not why I am follwing up. Expanding on my last comments, when I cut the pipes off and inspected the catalytic converters the driver side one had lost the last section of “honeycomb”. It appears there are 2 separate honeycomb sections in the cylindrical converter. However, I didn’t get a code for catalyst inefficiency. I now understand why the aftermarket converters are so much smaller. It seems half of the catalyst material is enough to do the job.

I probably could have just cleared the clogged material and replaced the muffler and continued on. But, I already had the y-pipe with cats thanks to Lunchbox.

But, my hope to break even on cost, like the last time I replaced them on another one, isn’t going to happen with the large drop in scrap catalytic converter prices.