1981 308 sounds like the Jetsons spaceship

I’ve got a very consistent noise that seems to be coming from my 308’s exhaust. I just got the car and know very little about it’s previous history. The noise is very much ‘load dependent’ in that it’s not there at idle, is very consistent when you add a little load, and gets more prominent if you add more load. You can literally feather the noise in and out with the accelerator pedal, hot or cold. The frequency is tied to engine rpm, but the volume is tied to engine load. It reminds me of a VW bug or the spaceship on the Jetsons cartoon. I’ve found posts indicating it’s coming from the mesh in the exhaust pipe tips, and others saying it’s from the emissions sampling ports in the exhaust manifolds. It appears to have the original cats and muffler, and the sampling ports (at least on the rear bank where I can see them) seem to be severed and pinched shut. Is this a normal characteristic? If not, is it serious? Is it relatively easy to eliminate?

 

Thanks for your replies.

I took a closer look based on some of the comments. On the rear bank (that I can see easily) one sampling port has a plugged extension tube intact, 2 others have plugs in them, and one has what looks to be an extension that's pinched off. The forward bank has the tubes installed (see attached photo). The air injection tubes are installed (at least in the rear bank that I can see) as is the air pump (although the belt's missing).

If the air injection tubes are all installed (and intact), could they still be making the noise?
Could the sampling tubes be making the noise?

One comment indicated the WAR could be causing the noise, but how can that be diagnosed other than replacing it?

Any input regarding the meshed exhaust pipe tips?

Thanks for your replies.


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Thanks for all the responses but I’ve still got some more questions.

I’ve seen several threads detailing this type of problem; some say their tubes are intact, some say they’ve been removed (and still make some type of noise), and some say it’s caused by the exhaust tips.

Is it correct to assume that this noise was NOT present when new and was the result of some type of system degradation?

Inserting sleeves in the exhaust tips seems like the easiest and least invasive solution, but if it’s only covering up a potential time bomb (deformed air injection tubes that could break off and go through the engine) then it doesn’t seem like a great idea.

As stated before I’m new to this game and appreciate all of the input. The thought of pulling the engine out of a car I just purchased is not at all appealing, especially if I’m not even sure that I’m chasing the same noise and/or eliminating the air injection system will fix it.

 

Two sheets of K&S Mfr #87181 .018 stainless steel ($7.99 each at Ace Hardware) did the trick. I took it for a long drive, the noise is absolutely gone, and none of the inserts blew out. I’ll call it a win. Thanks for the suggestions!