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I have a 1.3L Skoda Felicia, (carburetter engine without catalytic nor other gimmicks). Since past 1-2 months I would hear the exhaust sound has changed, it became more and more audible and at full throttle it sounded like a spitting with your tongue between lips (kind of like buzzing?). Recently, in past several days it started to change and gained additional bass and overall pitch has become more like a tractor. All the sound effects kick in after 1500-1800rpm and throttle more than 20% open. If I drive smoothly the exhaust almost not audible.

From what I know my exhaust consists of 3 parts (Y-pipe from engine and 2 resonators connected with pipe). Y-pipe looks quite rusted, but holds ok and I doubt it would degrade in described fashion, but maybe I'm wrong.

Here's the question - what part of my exhaust needs changing and how could I verify/check it without garage nor extra tools?

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5 Answers

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You can block one end while engine running and see if you can detect smoke coming out somewhere in the pipe/box (remember that the exhaust gets hot and if blocked for too long the engine will stop).

Other way is to visually inspect each element and see if they are fitted correctly, you should look for parts that can be easily disconnected.

Remember that some exhaust "boxes" have different components inside that can fail to remain attached, including some small pipes that help to reduce the noise. If that is the case you may need to replace that part of the exhaust. To cheek if that is the problem just give it a little shake (engine stopped) to see if you can hear any noise of losing parts inside.

Also you didn't say if the noise come from the front of the car or the back. If the noise come from the front you may check if the start of the exhaust is correctly attached to the engine and check for signs of broken/burn exhaust gaskets

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It sounds like a gasket might have blown out. Probably near the engine head, so the exhaust manifold itself.

You can try soapy water on the joints/mating surfaces to see if there are any bubbles coming up when you start the engine. Try this on a cold engine though, as it won't last long before it all evaporates.

But I'm willing to bet it's a gasket near the manifold.

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If I see rusted areas, I poke them with a screwdriver to see if they're solid. Other than that, start up the car on a cool morning and look for vapor coming out from places other than the tailpipe.

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Raise the vehicle on to jack stands or drive on ramps. With the engine running have a friend hold a rag over the tailpipe. Crawl under the vehicle. Move your hands around the exhaust system while listening and feeling for the leak. Be careful how close you get your hands to the exhaust system as it will get hot. If no leaks are found it is possible that the baffles or sound packing in the muffler have failed and the muffler needs to be replaced.

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If I were you, I first touch with hands every area of exhaus. If I don't find anything, its possible exhaust has the small holes. Then I start engine ant touch with hand again.

With ear you cant fint exactly location.

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I wouldn't touch the exhaust with bare hands after the engine has been running for a while, it gets hot. –  Tim Jun 1 '12 at 13:32
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