The exhaust had gotten louder over the last couple of drives so I peered underneath and found the muffler blown out:
Click to view attachment

Here's a close-up.
Click to view attachment

I realize this is from an internal backfire, but what does this indicate and why did it happen? I never heard a "bang" or "pop" - only noticed a louder exhaust.
Thanks,
Tom

bursh?

Also add that they rust out from the inside, thinning the metal from the condensation formed when the engine is shutoff.

its a bursch thing....
Go to AutoZone and get a Hush Thrush muffler that is the same length with the same location of the in and out tubes...with tubes the same diameter and cut that one off and the tail pipe...then weld (or clamp) a new muffler in its place.

20 bucks was the last one I bought.

Rich

They rust on the shelf.

great tip (so far ) Rich, i'm bookmarking this one.

Just wait for it

Thanks for the tip, Rich. This muffler doesn't really look all that rusty - the metal is torn and cracked. I can't figure out what caused it. Maybe vibration?

its a bursch thing.

Rich

i have one that the muffler fell apart internally...just about to weld on a turbo replacement..if you search the word "bursch" you can read endless threads on it good luck,Dave

it looks like the primary pipe being that close to the muffler right there has caused some severe extreme heat cycling and has caused the sheet metal to expand and contract to a greater amount compared to the surrounding metal hence fatiguing that section to the point of failure.

That's very plausible. I took a closer look and indeed the muffler proper is/was touching the pipe. The muffler really does not fit well. So it's a bursch thing

it also appears that the muffler is not original to the exhaust system, it looks to be a replacement muffler that does not quite fit properly.