Bodywork, parts inventory and technical findings – Mercedes-Benz 290 W18 restoration after failed attempts
At the end of 2023, this Mercedes-Benz 290 W18 arrived in our workshops – the oldest vehicle entrusted to us to date. This factory-built, short-wheelbase convertible had undergone several restoration attempts, some abandoned, others poorly executed.
Previous modifications are rarely fully documented. Body panels may have been provisionally fitted, welds filled with putty, or parts from other vehicles installed. Only a thorough assessment will determine what is still usable and where a new start is needed.
Especially with an open-top pre-war Mercedes on a short chassis, the fit of many parts is crucial. Doors, A-pillars, window frames, sills, and convertible top connections must all function together. Previous modifications may have shifted these points without it being immediately noticeable. Furthermore, the steel-wood body construction of this era means that the wooden frame and steel panels behave differently, and repairs that only address one of them will create subsequent problems.
The parts inventory is recorded separately. Missing or incorrectly identified parts from previous restoration attempts must be identified before materials are procured or new parts are manufactured. Work on the body, woodwork, and mechanical components is then addressed systematically.
Steel and wood body and open design on the short W18 chassis
The convertible bodies of the Mercedes-Benz 290 W18 were constructed using a steel-wood frame: a wooden skeleton with attached steel sheets. This makes restoration more complex than with a purely steel body. Both the wood and the metal must be assessed simultaneously. Wood can shrink, crack, or become permanently damp; the contact points with the metal are frequent corrosion points that are not always visible from the outside.
On the Mercedes 290 Cabriolet, the convertible top frame, door fits, and window frames are additional critical areas. Incorrect preparatory work becomes apparent at the latest in panel gaps, chrome parts, seals, and convertible top connections. Especially with a factory-built convertible with a short body, the basic shape must be correct before discussing paintwork, interior, or chrome restoration.
Straightening work, rust removal and technical inspection according to findings
Previous work is first uncovered and assessed. Poor welds, filled joints, incorrectly fitted sheet metal, or unclear wood repairs must be rectified before seam sealing, cavity protection, and paint preparation can be properly carried out. Straightening work and rust removal follow based on the actual findings, not a wish list.
Parts for the W18 Cabriolet are a complex issue in themselves. Production numbers for these variants were small, and many fittings, trim pieces, convertible top components, interior parts, and technical components cannot simply be ordered off the shelf. Therefore, missing or incorrectly identified Mercedes 290 parts are either traced, refurbished, or newly manufactured.
The side-valve 2.9-liter six-cylinder engine with overdrive gearbox, brake system, and swing axle undergoes a separate technical inspection following the bodywork assessment. Engine, carburetor, ignition, cooling system, fuel system, gearbox, axles, steering, and brakes must be assessed step by step in this pre-war car. A technical restoration is only worthwhile if it is clear beforehand which components are complete and which previous work needs to be reopened.
Have your Mercedes-Benz 290 W18 restored – even with a difficult history
For vehicles with a restoration history, photos of the body, frame, doors, window frames, wood trim, convertible top frame, engine compartment, and available parts are a good starting point. Especially with a Mercedes-Benz 290 W18 Cabriolet where preliminary work was interrupted, an early inspection is crucial to ensuring the project remains manageable.
In our workshops in the Czech Republic, we examine how bodywork, rust removal, woodwork, technical overhaul, painting and interior fittings realistically fit together – and what is feasible for a vehicle with multiple restoration attempts.
