Brackets

Mounting hardware for exhaust pipes and silencers must seal joints, support component weight and control vibration without restricting thermal expansion. Exhaust clamps, retaining straps, support brackets, rubber-to-metal mounts and bolted joints each serve different functions. An incorrect clamp diameter or a preloaded mounting can not only cause exhaust leaks but also damage exhaust flex pipes, connecting flanges and turbo connections.

U-bolt clamps apply localised clamping force to overlapping pipe joints; wide band clamps distribute the clamping force over a larger area. V-band clamps pull matching flange profiles together axially. Silencer straps and support brackets support the exhaust silencer, while rubber-to-metal mounts isolate vibration where specified by the vehicle design. These types are not interchangeable.

Always identify parts using the vehicle's chassis number. Visual comparison or selection based solely on the model name is never sufficient. On MAN TGL with D08 engines, MAN TGX with D26 engines and Mercedes Actros with OM 471 engines, the emissions standard, wheelbase and exhaust position may require different mounting hardware. Mounting arrangements also vary by version on Mercedes Sprinter, MAN TGE and buses such as the Mercedes Citaro.

Check the pipe outside diameter, clamp width, flange angle, bolt length, thread pitch and mounting hole centre spacing. Fit, roundness and permissible dimensional tolerances must meet the manufacturer's specifications. Material selection, such as coated steel or stainless steel, depends on thermal loading and the corrosive environment. Use only the specified bolt strength grade, locking method and elastomer grade; a universal rubber exhaust mount is not necessarily resistant to the radiant heat at its mounting location.

Soot marks around joints, ticking noises under load and signs of contact with the chassis indicate leakage or movement. Corrosion reduces the cross-section of silencer straps; thermal cycling can reduce clamp preload. Hardened or cracked rubber-to-metal mounts cause resonance and place additional loads on adjacent welds.

1. Allow the exhaust system to cool and support heavy silencers before loosening the mounting hardware. Inspect retaining straps, brackets, welds and threads for cracks, wear and material loss due to corrosion.
2. Measure the pipe outside diameter with a vernier calliper in two perpendicular directions to check for ovality. Check for flange damage and assess flat mating surfaces using a straightedge and feeler gauge where the design permits.
3. Check the mounts for play and compare clearances to the chassis, heat shields and lines with the installation instructions. If failures recur, also inspect the engine mounts and exhaust flex pipes.
4. Locate leaks using a suitable smoke tester on a cooled system, strictly following the vehicle-specific procedure and limiting the test pressure. Do not use unregulated workshop compressed air; mounting clamps cannot be used as a basis for determining a safe test pressure.

Replace deformed clamps, worn straps and damaged mounting bolts. Fit new sealing rings and single-use locknuts where specified. Clean contact surfaces without removing material that determines the fit. Tightening the clamp further will not reliably seal a corroded or oval pipe connection.

First position the pipes and silencers with the mounting hardware loosely fitted. Allow for the specified insertion depth, thermal movement clearance and neutral position of the exhaust flex pipes. Then tighten bolted joints in the specified sequence using a calibrated torque wrench. Use assembly paste only where permitted: changes in thread friction affect preload.

After installation, check for leaks, resonance and unwanted contact with the engine running and suitable exhaust gas extraction in place. Carry out a follow-up check after a heat cycle in accordance with the manufacturer's instructions; retightening is not permitted for every clamp. Braem can provide technical support in identifying suitable mounting hardware.