BMW 335: revive the M54 mechanically and make it as reliable as possible

This video chronicles a full mechanical revival of a neglected BMW 335 with an M54 engine: an engine-out cleanup, gasket and seal replacement, recharge of major systems, and diagnosis of multiple cascading failures. The shop discovered extensive sludge, a missing or botched 'all pan gasket' job with broken/torqued-off bolts, and obvious long-term neglect. They installed a valve cover, accessories, brand-new '17T turbos' ("China for the win"), plugs and coils, and cleaned the engine before reinstallation.

Major problems found and fixed (summary with shop actions and outcomes):

• Oil/engine sealing and hardware: missing/broken oil pan bolts required extraction; the valve cover and pan gasket were replaced and the engine thoroughly cleaned to restore reliability.
• Exhaust/downpipes and drivetrain fitment: preinstalling downpipes caused fitment pain; lesson: install downpipes after the motor is in the car. Transmission was refitted and a polished stainless exhaust with 3.5" single pipe was installed; final tip choice were Turner 'bazooka'-style tips.
• Brakes/ABS/DSC: the car arrived with 'zero brakes'. They replaced rotors/pads, added stainless braided lines, inspected DSC, and discovered an ABS pump with a stuck separator valve that needs replacement. The shop notes the ABS pump is inexpensive (~$70) but its absence delayed completion.
• Vanos, cam ledges and oil screens: persistent Vanos codes led to removing the valve cover and cam components. They found clogged Vanos screens with gritty debris and damaged cam ledges; both intake and exhaust cam ledges require replacement and new Teflon seals. The quoted price for OEM cam ledges was stated as '2900'.
• Sensors and belts: a low/erratic fuel pressure reading pointed to the fuel pressure sensor under the intake, which they replaced; a noisy belt was replaced with an OEM unit and resolved a major squeal. After addressing Vanos screens, seals, and the belt, Vanos codes cleared and the engine ran markedly healthier.

Shop recommendations and cautions from the video: use OEM Vanos solenoids and timing-related parts ('OEM only'); avoid cheap aftermarket Vanos parts. Do not preinstall downpipes when dropping a motor back in. Expect cascading failures on long-neglected cars: small parts (screens, seals, sensors) can create code storms that mask root causes.

Final state: mechanically healthy for street use except for outstanding items (ABS pump replacement and some EVAP/cooling hold-up noted). The car drives as a 'sleeper' with improved performance but would benefit from a proper Stage 2+ tune and further supporting mods for full power.