When Your Silencer Doesn't Silence: Diagnosing Car Exhaust Silencer Problems By Sound

Posted on: 14 December 2015

Hearing strange sounds coming from your car is never a pleasant experience, and in many cases the car exhaust system is to blame. This intricate series of pipes, filters and mufflers can malfunction in a number of ways, and its complexity can often leave amateur mechanics stumped when it comes to finding the source of the strange noise. However, before you throw away your tools in despair and call in the mechanics, pay close attention to your exhaust's silencer, and the noises it is making -- many exhaust problems produce distinctive noises, which can help either you, if you already have some experience with cars, or the mechanics diagnose and fix the problem much more quickly and easily.

Loud roaring

If your car exhaust has become unpleasantly loud, particularly when accelerating or at high revs, you probably have a hole or crack in your exhaust silencer, the large, boxy structure at the end of your exhaust pipe that muffles engine sound. If the damage is externally visible on the body of the silencer itself, it can be patched effectively at home, either with welded metal plates or specialised airtight epoxy sheets that are cut to size. However, if the crack has occurred in an awkward position, such as the seal fitting the silencer to the exhaust pipe, you may require professional help.


A persistent humming or buzz that occurs while driving can indicate an exhaust that simply isn't fit for purpose, particularly if it only occurs at a certain number of revs. This buzzing is caused by excessive vibration within the silencer or resonator (if your car has one), and generally indicates one of two things:

  • Your exhaust has taken a knock or dent, changing the shape of the silencer and reducing its ability to reduce noise.
  • Your car has been fitted with an aftermarket exhaust system that is either poorly fitted or designed for lower-capacity engines.

In either case, it's a safe bet that your silencer will need to be replaced. Stock silencers intended for your particular model of car are best, but can be difficult or expensive to find. Talk to an exhaust specialist, who will be able to assess the scale of your problem and recommend suitable replacement parts.


If your car has started to sound more like a steam train than an automobile, and engine noise has taken on a rhythmic chugging noise, you may have a blocked exhaust system. A blockage can occur at any point along the exhaust line, but the bafflers inside your silencer are one of the key culprits, since they tend to degrade and collapse over time, blocking normal air flow through the complex internal arrangement of the silencer. In any case, it's important to have this problem seen to by professional mechanics as soon as possible --  a blocked exhaust pipe can easily become a leaking exhaust pipe as the build up in air pressure causes metal fatigue, potentially causing harming carbon monoxide to leak into the interior of the car.