Exhaust noises?

[edgemaster]

Hi Guys, I have a 2009 LTD with about 125k miles, that makes noises lately. The wife says after driving for about half an hour the car gets louder as if the exhaust system was leaking somewhere. So I crawled under to check things. All the rubber hangers look god and are intact. I noticed that small muffler just behind the cat. It is connected to the rear part of the exhaust system with a large clamp and the pipes are stuck one inside another. What's weird is that the smaller pipe is slightly clean for about 1/2" as if those 2 pipes are kind of loose and slip back and forth. Is it possible that, after the exhaust system is sufficiently hot, the 2 pipes get loose and a small exhaust leak develops? Is this a known issue or am I imaginating things?  

[enigma-2]

Looking at the literature, there is apparently a gasket (located at the mid-pipe to catalytic converter) that degrades over time, or the flange ears can rust off.

 

One suggestion to verify this is to connect the reverse output from a shop vac to the tailpipe with duct tape to make an air-tight connection. Then using a squirt bottle of soapy water, spray the solution on all the joints looking for soap bubbles from the air escaping. 

 

There should NOT be any places along a worn exhaust system where it's shinny nor have traces of black from carbon. (Telltale signs.)

 

If you find even a small leak, have it fixed immediately as CO2 is dangerous inside the cabin.

[edgemaster]

Thanks for that info. I'll do a check as you suggested, hoping the leak shows itself on a cold muffler system.

[edgemaster]

enigma-2: Are you talking about gasket 5C226?

[Samurai Edge]

My initial thought, as enigma suggested, would be any doughnut or gasket connection between the exhaust pipes.  That's typically the first place to start.

 

Look at highly rusted areas and tap on them with the handle of a screwdriver.  Listen for dead sounds as opposed to ringing sounds when tapping.  A dead sound is an indication of worn out areas which you obviously can't see.

 

Check all the muffler connections as well as the muffler bodies themselves.

 

A sure-fire way to find leaks if they don't become obvious, is to put the car up on a lift or high quality ramps or jack stands, start the car, and giving it a few minutes to warm-up, crawl underneath and listen for where the leak may be coming from.  Done it more than once.

 

BTW, if the exhaust heat up, and the two (2) pipes were slightly loose when cold, the pipes will expand as they heat up and seal the small space closed.  We are talking about small gap.  Some headers were designed to work that way.