Loud noise in Exhaust system?

Question

My car(99civic hx) have a loud noise coming from the Exhaust. If the car is in park and I step on the gas, I don't hear that kind of noise, but when I'm on the road, 40mph and up, it starts to make a loud noise like big truck reducing speed from 4th gear to 3rd gear. I replaced the muffler, the gasket, and another gasket on the other end of extension pipe,under the engine (no holes). But the noise still there. It stop only if I turn right at a curve. Where the noise is coming from and how can I fix it? Please don't tell me to go to a garage. Thanks

Answer 1

You may have a seam that has broken on the exhaust pipes leading to the catalytic convertor or one of the joints. It gets louder on the road perhaps because it widens as the heat or wind is getting at it.

Since you hear it less when you turn right, that means that it is likely on a seam or joint that closes with the added force of the car turning.

Look for a rusted joint or broken seam on the right edge of the exhaust system, probably in front of the muffler or catalytic convertor. It is probably easier to do this if it is up on a lift.

If it has just come apart at the joint, it may be possible to weld or otherwise fix the exhaust pipe. If it came apart at the catalytic convertor, it may require changing that, which is expensive.

If you don't have to meet emission requirements and the catalytic convertor is the problem, see if the garage is able to install a resonator instead. Much less expensive, but does not do as good a job to clean the air coming out.

Answer 2

Make sure the muffler is perfectly level. If it isn't you it can collect water in the low spots and get little loud steam explosions when you turn corners or let off the gas and reduce exhaust pressure.

Answer 3

Your exhaust system is making contact with the body under a load. Inspect the system carefully and pull on the hangers to determine where the contact is being made. Once you determine where the noise is being created at you can adjust the pipes/muffler or replace the hangers to make it stop.

Answer 4

Sounds like the catalytic converter may be plugged when your going 40 the pressure may blow it open. But I don't think so. This is very unusuall. Expecially when you mentioned when you turn right from a stop. I don't think it's the exhaust could be a cv joint. Do you notice a shaking in the front end. Sorry can't help without knowing more or seeing it myself.

Answer 5

I have NO mechanical ablility but thankyou, thankyou, thankyou for wanting to cut out the noise. I hope it's not a mechanical problem that will affect your driving but someone in America actually isn't trying to annoy everyone else with a noisy muffler.

You are one of the few who apparently doesn't have a problem with penis size. You're my hero.

Answer 6

When the air gets' flowing I bet it is the catylitic converter falling apart and rattling.