Exhaust System Repair and Inspection

The most obvious sign is a louder engine, especially on cold starts or when accelerating. Others include a ticking sound near the engine that fades as it warms, a metallic rattle underneath, a sulfur or raw fuel smell, fumes inside the car, a check engine light, and lower fuel economy. Each points to a different part of the system.

A leak ahead of the oxygen sensors can let outside air in and confuse the readings, which can set codes. See check engine light diagnostics when a light is part of the picture.

Exhaust contains carbon monoxide, which you cannot see or smell on its own. If you notice an exhaust smell inside the car, or feel headaches, dizziness or drowsiness while driving, open the windows, limit driving, and get the vehicle inspected right away. This is a need item, not something to put off.

Common sources include leaks near the front of the vehicle, rusted pipes under the passenger area, a damaged tailpipe that ends too close to the body, and worn trunk or tailgate seals. We check both the exhaust system and the body openings that could let fumes in.

The catalytic converter cleans exhaust gases, and California makes removing one illegal. The same law limits passenger vehicle exhaust noise to 95 decibels and requires the system to be in working order. Converters usually fail because of an engine problem upstream, like a misfire or oil burning, which overheats or coats the inside. Replacing a converter without fixing that cause often ruins the new one, so we check engine health first.

Things to know:

• A rattle inside the converter shell can mean the internal core has broken apart
• A flashing check engine light means a misfire bad enough to damage the catalytic converter, so ease off and get it checked
• Replacement converters must meet California requirements for your vehicle
• Converter theft has been a problem in many areas; a sudden, very loud exhaust after the car was parked can be a sign

If a converter was stolen, we can inspect for other damage and quote a compliant replacement. Details on current emissions rules are published by the California Bureau of Automotive Repair (opens in a new tab).

We raise the vehicle and follow the system from the engine to the tailpipe. We look for holes, cracked welds, rusted pipes, broken hangers, loose heat shields and damaged flex joints, and listen with the engine running. For hard-to-find leaks, we may use smoke or feel for pulses at joints on a cold engine. Photos show you exactly where the problem is.

Many exhaust fixes are small: a new hanger, a clamp on a loose heat shield, or a gasket. Others need a section of pipe, a muffler or a converter. We quote what the inspection supports and mark which items affect safety and which only affect noise.

Exhaust parts near the rear wheels can rub on suspension parts if hangers fail, so we check suspension mounts nearby at the same time. Shopping for a used car? Exhaust rust and leaks are part of every pre-purchase inspection. On a private sale in California the seller provides a smog certificate less than 90 days old unless the vehicle is 4 model years old or newer.

Some exhaust problems can wait a short time and some cannot. Fumes in the cabin, a pipe dragging on the road, or a loud leak near the engine with a burning smell should be handled right away. A heat shield rattle or a small leak at the tailpipe can usually be scheduled. This table sorts the common ones by urgency.

When in doubt, call (909) 608-7699 and describe what you hear and smell. We will tell you whether to drive in or arrange a tow.

The shortcuts that come back are the ones that hide a problem instead of fixing it: wire holding up a muffler, tape over a hole, or a heat shield removed to stop a rattle. They quiet the car for a while, but the leak, the heat or the loose part is still there. A proper repair uses the right hanger, clamp, gasket or pipe section.

Shortcuts we see on cars that come in:

• Coat hanger wire instead of a hanger. It rusts through and lets the system drop again.
• Exhaust tape or paste over a hole. Heat cracks it within weeks on most systems.
• Heat shields pulled off. The shield protects the floor, fuel lines and anything you park over, like dry grass.
• Clamps over rotten pipe. The clamp crushes weak metal and the leak moves an inch over.
• Ignoring a manifold tick. Leaking manifolds can break studs over time, which turns a gasket job into a drilling job.
• Aftermarket or removed emissions parts. In California, emissions parts must be legal for your vehicle, and missing or modified parts can fail the visual part of a smog check.

Why short trips matter here

Exhaust makes water as it burns fuel. On short errand trips along Foothill Blvd, the system never gets hot enough to dry out, so moisture sits inside the muffler and pipes and rusts them from the inside. Cars that mostly make short trips tend to need exhaust work sooner.

Misfires also hurt the converter, so a rough-running engine should be checked under tune-ups before a new converter goes in.