Hi, I have a 1997 Civic Ex and I recently noticed my AC starts to have a gas odor pouring out when I'm stopped. My car also has gotten much louder sounding more like lawn mower :/. I think it might be the intake manifold or the manifold gasket not sure. I would like you guys input btw I am new to car repair or cars in general.

 

Open the hood and idle the engine and look around the fuel rail and gas lines for leaks. Do not drive the car any with gas leaking out anywhere, as that is a severe fire risk.

Increase in noise like that usually is because one of the exhaust pipes has rusted a hole in it. With the engine idling, temporarily block the tailpipe with a rag. Pressure should build up quietly. Any small holes in a pipe will make a hissing noise under the car. If you don't get any pressure buildup at all, the pipe is completely broken.