Solutions For Common Exhaust Problems

Your vehicle's exhaust system's primary function is to extract or 'exhaust' gasses from the engine of the car out and away efficiently without causing any toxic fumes to enter the vehicle's cabin.

A car's engine is really just a big air pump sucking both air and gasoline/diesel into the cylinders, then igniting it, causing the hot expanding air to power the engine. These hot gasses have to be expelled, and your car's exhaust system is tasked with this function.

The exhaust system has four main parts. The exhaust manifold, otherwise known as the exhaust header, the catalytic converter, the muffler, and lastly, the tailpipe. These parts are, in turn, all connected in-line with steel piping, typically manufactured from mild steel or more expensive and durable stainless steel.

Let's have a look at each part in turn and share some common problems that can happen and suggested solutions for problems with the exhaust system.

Exhaust header

The exhaust header is bolted to the engine's exhaust ports and takes the hot exhaust gasses down to the catalytic converter or a turbo if the vehicle happens to be a forced induction type engine. 

Either of cast iron design or a more performance-oriented tubular pipe header, the exhaust header is designed to operate under extreme pressure and heat around 400 to 500 degrees Fahrenheit. Those vehicles with high-performance pipes can reach temps as high as 1000 degrees Fahrenheit. 

Such high temperatures, along with the vibration from a revving engine, will, unfortunately, lead to exhaust problems in the long run. An unusually noisy engine note is one the clearest indicators of an exhaust manifold that has cracked and started leaking. Along with strong exhaust smells, the vehicle's fuel economy may suffer with poor performance and even a check engine light (CEL) being illuminated on the dashboard.

Cracked cast iron manifolds are normally easy to spot on visual inspection and will require either a replacement or, if a more cost-effective repair is preferable, specialized welding by a suitable workshop. Tubular-style headers are also prone to cracking, particularly around welded areas, and will require similar repair.

All internal combustion engines utilize a gasket to create a seal between the exhaust header and the engine. Failure of this gasket will cause similar noise and performance issues, such as a cracked exhaust header, and will require the removal of the exhaust header to enable the replacement of the gasket. This is relatively inexpensive parts-wise but does require some handy DIY skills or the use of a dealer's service center or workshop.

Not fixing these problems quickly enough may, unfortunately, lead to the premature and expensive failure of the engine's head gasket and overheating.

Catalytic Converter

The catalytic converter is the exhaust emission control device that converts the toxic exhaust gasses and pollutants into less harmful exhaust emissions through chemical reactions between the gas and the precious metals found in the unit.

Failure of catalytic converters is normally due to overheating, melting, or breakage. This leads to problems including incomplete combustion, causing engine misfires and difficulty starting your car, as well as a noticeable drop in performance, along with reduced acceleration.

Bad smells like rotten eggs or sulfur are a sure sign of a clogged-up catalytic converter, along with dark exhaust smoke or extreme heat from under the vehicle. Cleaning of the converter is possible if still relatively new. 

The lifespan of a catalytic converter is usually around ten years.

Internal damage due to age and gasoline products to the honeycomb filter structure can also result in a noisy, rattling converter. 

Unfortunately, repair of these units is not a realistic possibility, and replacement costs tend to be expensive.

Mufflers

Mufflers are part of the exhaust system designed to keep exhaust emission noise levels down to bearable and legislated levels.

Made with either stainless steel or mild steel coated with aluminum to provide protection from the chemicals and heat in the exhaust gasses. 

The relatively heavy weight of the muffler means that a steel bracket is typically welded to the muffler, which in turn is attached to the underside of the vehicle using a rubber hanger. This rubber hanger allows the exhaust to move around a little bit along with the engine to help prevent cracks in the exhaust system as well as reduce vibrations and noise entering the vehicle's cabin.  

Problems that can occur with mufflers include rattling due to physical damage, failure of the rubber hangers, rusting, and subsequent perforation. A damaged muffler will result in reduced vehicle performance, higher noise levels, dangerous toxic fumes entering the vehicle's cabin, along with loss of fuel economy. 

Easy, inexpensive repairs are possible but only recommended if the muffler has minor damage. 

The exhaust muffler is typically vulnerable to pothole damage, road debris, or even speed humps, and any small cracks and small holes caused by these hazards can be patched with specialized adhesives that bond to the exhaust muffler surface.

Replacement of the muffler due to physical heavy damage or deterioration due to rust, if the muffler is constructed of mild steel, is the only possible remedy.

Failure of the exhaust rubber hanger will result in the exhaust system rattling and bashing against the chassis or even, in the worst case hanging low and hitting the road surface. Rubber hanger replacement is an easy repair for both the DIY mechanic and workshop but requires the vehicle to be lifted on a hoist to access the underside of the vehicle.

Tailpipe

Just like the chimney on the house, the tailpipe is designed to release exhaust gasses away from the rear of the vehicle and out into the air.

The design and function of the tailpipe are mostly aesthetic, and modern sports cars, for example, use double-pipe outlets to portray a sporty, high-performance look.

Possible problems with this part include rusting, falling down, rattling, or physical damage.

Repair of any of these problems will normally entail a quick and easy replacement of the tailpipe. With such a massive interest in aftermarket performance and styling parts, there are plenty of tailpipe products to choose from.

As mentioned, these components are all connected with the tubular exhaust piping, which itself may rust and perforate if constructed from mild steel or even get damaged by any road debris or obstacles. Repair is generally out of the scope of the home mechanic, and replacement of the damaged section by a recognized workshop like Granite Subaru is recommended.

Call or visit our team of experts at Granite Subaru if you are experiencing any above-mentioned exhaust problems, whether it be your Subaru or another make, and we will gladly inspect your vehicle and offer a repair solution.