Engine support metal

A metal engine support provides the load-bearing connection between the engine block, transmission housing and chassis or subframe of MAN and Mercedes trucks, buses and vans. Unlike rubber-metal mounts or hydraulically damped engine mounts, this support primarily absorbs structural forces: engine weight, reaction torque during acceleration and deceleration, vibration loads and dynamic loads caused by uneven road surfaces. The design varies considerably depending on the chassis, engine position, cab configuration and transmission. Selection based solely on the model name or visual comparison is never sufficient; always identify metal engine mounts, support arms and mounting brackets using the vehicle's chassis number.

Metal engine supports are available as cast aluminium supports, nodular cast iron brackets, forged steel support arms or welded steel constructions. They feature precisely machined mating surfaces, locating bushes, threaded holes and bores for engine mounts, chassis mounts or transmission mountings. The fit of locating pins and bolt holes is essential: a support installed under stress causes premature wear of rubber-metal mounts, driveline misalignment and additional stress on exhaust flex sections, coolant pipes and propeller shafts.

Depending on the vehicle series and engine family, the shape, height, centre-to-centre distance and mounting points vary significantly. This applies to MAN engines D08, D15, D20, D26, D28 and D38, as well as Mercedes engines OM 364, OM 366, OM 402, OM 421, OM 422, OM 441, OM 442, OM 457, OM 460, OM 501, OM 502, OM 503, OM 904, OM 906, OM 926, OM 934, OM 936, OM 470, OM 471 and OM 473. Even within the same engine family, the Euro emissions class, engine brake specification, PTO configuration, automatic or manual transmission and vehicle application may require different supports.

Metal engine mounts do not wear in the same way as elastomer mounts, but they can crack, deform or develop excessive play due to fatigue, overloading or a previous collision. Typical fault symptoms include a dull knock during load changes, visible engine movement, abnormal vibrations in the cab or steering column, cracked exhaust components and repeatedly loosening mounting bolts. On heavy-duty tractors, a cracked bracket can develop after prolonged driving with a defective engine mount; the metal support is then subjected to peak loads for which it was not designed.

First inspect the engine and transmission mountings on a vehicle lift. Carefully relieve the driveline using a suitable engine support bar or transmission jack, without supporting the engine block on the oil sump. Then inspect welds, ribs, corner transitions and bores for hairline cracks, corrosion and deformation. Use a vernier caliper or dial gauge to measure the play in locating bushes and check the flatness of mounting surfaces with a straightedge. Compare the engine height on the left and right; a difference often indicates collapsed engine mounts or a distorted support bracket. Also inspect the bolts for stretching, damaged threads and oval holes.

Replace a metal engine mount in the event of proven cracking, permanent deformation, worn locating holes or damaged threads. Welding is only justified where permitted by the manufacturer and where the material type, heat input and dimensional accuracy can be controlled; for cast aluminium or cast iron supports, replacement is the only safe solution. Install the new bracket together with an inspection of the associated rubber mounts, spacer bushes and fastening materials. Use new bolts where the manufacturer specifies angle tightening.

Thoroughly clean the mating surfaces, position the driveline without stress and tighten the fasteners to the specified torque and any required torque-angle procedure. Only then should the engine support bar or jack be removed. After installation, check the clearance around the fan, exhaust system, propeller shaft and lines. Technical support and a wide availability of new, used and inspected parts help minimise downtime for trucks, buses and vans.