The R107’s exhaust is a long, heavy system with plenty of joints, hangers and, on US cars, a catalytic converter. Leaks change the sound, can upset the O2 sensor, and can let fumes into an open car.
Exhaust layout by model
V8 cars have a cast manifold on each bank feeding downpipes that join into a Y-section, then (on catalyst cars) the converter, a center resonator or muffler and a rear muffler. Euro cars without a catalyst use a different front section. Six-cylinder 280SLs have a single manifold. Exact parts depend on year and market, so order by chassis number.
Common leaks
- Manifold-to-downpipe flanges and their gaskets
- Rusted clamps and joints at the center and rear mufflers
- Cracked or perished rubber hangers, which let the system knock and crack
- Holes in the rear muffler, which rusts first because condensation collects there
Manifold gasket ticking
A ticking that is loudest cold and fades as the engine warms often comes from a leaking exhaust manifold gasket or a loose manifold nut. It is easily confused with lifter tick (see lifter tick). Listen with a length of hose near the manifold joints, or look for black soot streaks at the head. Replacing the gaskets can be difficult because studs seize; soak with penetrating oil for several days and use heat carefully.
Catalytic converter issues
- Rattle: the internal substrate has broken up. It can block flow.
- Sulfur smell: often a sign of rich running; fix the mixture first (running rich).
- Glowing red or power loss: a blocked converter, usually from misfires or rich running. Stop driving and fix the cause.
Stainless options
Stainless steel systems last much longer than mild steel and are popular for cars that will be kept. Choose one that keeps the original sound and fitment, uses correct hangers and keeps the catalytic converter on cars that legally require it.
Emissions considerations
US cars were built with converters, and many states require them to remain. Removing one may be illegal where you live and can make the car fail inspection; check local rules. Illinois, for example, does not test cars of this age, but federal tampering rules still apply. See Illinois antique plates and emissions.
Quick answers
- Can exhaust fumes enter the cabin? Yes, especially with the top down at low speed or with leaks near the front. Fix leaks promptly.
- How long does a mild steel system last? On a car stored dry and driven regularly, years; on a car that makes only short trips, condensation can rot mufflers quickly.
- Should hangers be replaced with the system? Always. Cheap new hangers protect a new system.
