BMW X5 M50D ENGINE REBUILD
BMW X5 M50D N57 ENGINE PROBLEMS
Another BMW in for an engine rebuild, however the 3.0D tri-turbo N57 fitted to the X5 M50d differs slightly in a number of ways to the more common single and twin turbo variants. The latest M50d in for an engine rebuild arrived with typical symptoms common with the more powerful N57 variants and this was a seized engine. The engine was unable to turn at the starter.
The N57D30C (Tri-Turbo) variant generally has a stronger bottom end to cope with the higher power output. It manages this with much larger/longer main cap bolts and a different connecting rod design, however these improvements do not make the engine immune to failure. A lack of frequent oil changes and the negative contribution from the aggressive emission control systems (DPF, EGR etc.) still contribute to the same failures.
We removed the power unit, separated the gearbox from the engine, removed the ancillary components and stripped down the engine completely. As suspected we found one spun main bearing.
N57D30C ENGINE REBUILD
The engine block was taken to the engineer for a line bore, in the case of the tri turbo the main caps already utilize dowels (a process included with the engineering work on single and twin turbos). With the engine block back to spec and thoroughly cleaned a new crankshaft was fitted, along with all standard parts in the rebuild procedure.
After this the ancillaries components are reattached and the engine connected to the gearbox. The power unit is reinstalled onto the subframe and fitted back to the vehicle. After everything had been connected up and ready for testing we found the starter motor had been burnt out after roadside assistance and tried to start the seized engine so many times. An easy fix and the car is back on the road.
