Insulation

Insulation panels fitted alongside and underneath the engine and gearbox help dampen noise from the engine and driveline while protecting adjacent parts from heat, dirt and spray water. These insulating components are used on MAN trucks such as the F2000, TGL, TGM, TGA, TGS, TGX and TG3, and on Mercedes-Benz LN, SK, Atego, Axor, Actros and Arocs models. They may also form part of the underbody protection on buses, including the MAN Lion’s City, Lion’s Coach, Mercedes Citaro, Intouro and Tourismo, as well as certain Neoplan models. Selection by model name, year of manufacture or visual comparison alone is never sufficient: always identify insulation parts using the vehicle chassis number.

Engine and gearbox insulation components are generally moulded panels made of fibre-reinforced plastic, foam laminates, rubber elastomer or textile-like absorbent composites. Depending on the version, they combine acoustic absorption with protection against moisture, heat and stone impact. Unlike a visible undertray, insulation is mounted alongside or underneath the engine and gearbox, often using plastic clips, push pins, bolted connections or integrated mounting tabs.

The correct shape depends on the engine version, gearbox type, chassis height, wheelbase, air suspension, exhaust system and the presence of components such as EBS (Electronic Braking System) wiring, air lines, AdBlue components, heat shields or mounting brackets. On tractor units and rigid trucks, insulation for a specific engine and gearbox combination may therefore differ from a version for another driveline. Also check the clearance around moving parts, exhaust components and the propshaft; incorrect insulation may rub, come loose or be damaged by heat.

Common defects include torn mounting holes, detached clips, split edges and material that has become saturated or deformed due to prolonged exposure to moisture, oil or heat. On vehicles used in construction, waste collection or distribution applications, caked-on dirt can significantly increase the weight of the insulation. This can cause mounting points to break off and the component to sag onto engine, gearbox or exhaust components. Damage also frequently occurs after contact with obstacles, stone impact or work on the engine and gearbox.

During a periodic inspection, first check that the insulation is complete and does not contact moving parts, exhaust components, lines or wiring harnesses anywhere. Inspect for polished rubbing marks, fraying and worn areas. Around hot components, check the clearance according to the prescribed workshop procedure. Then inspect all mounting points for cracks in the underbody or at the brackets. Fitting new insulation to worn or broken retainers without repairing the mounting surface will quickly result in repeat damage.

Replace insulation when the material is hanging loose, retaining water, frayed or no longer maintaining sufficient clearance from engine, gearbox or exhaust components. Clean the mounting area beforehand and remove mud, road salt and corrosion around metal brackets. Use new clips, locking nuts or specified fasteners when the old ones are deformed, brittle or corroded. Do not fit a universal panel that blocks drainage or obstructs inspection of engine, gearbox or exhaust components. A correctly fitting insulation component reduces engine noise and prevents dirt from accumulating around vulnerable driveline components. Thanks to Braem’s stock-focused parts supply, vehicle downtime during repairs can often be kept to a minimum.