Both engines are 3.0-litre straight-six diesels, and both were fitted to a 530d. That is where the similarity ends. The M57 is the earlier iron-block engine, used into the E60 and E70. The N57 is the later aluminium-block engine in the F10, F15 and early G30. A listing that only says "3.0 diesel" is not enough to order from.
Different generations
The M57 came in single-turbo and twin-turbo forms. M57D30TU and M57D30TU2 are the codes you will see on later cars. The N57 added more electronics, a different fuel system and, on many cars, swirl flaps in the manifold. The gearbox bellhousing and the engine loom are not shared. This is a replacement of like for like, not an upgrade you bolt in over a weekend.
What fails on each
On the M57, swirl flaps on the early manifold, the thermostat housing and the turbo hoses are the usual extras. The bottom end is generally the reason people still look for these engines. On the N57, the flaps, the EGR cooler and the chain at very high mileage are the questions. Neither engine should be bought with coolant in the oil.
Ordering the right one
Read the stamp. If the old engine is already out, the VIN of the car still tells us the code it left the factory with. xDrive cars need the matching oil pan. Automatic cars need the flexplate, not a manual flywheel.
M57 guide · N57 guide · N57D30A from a 730d
At the ramp
Keep the gearbox that belongs to the car unless you bought the pair together. An M57 flexplate and an N57 flexplate are not a detail. Neither is the engine loom. Photograph the connectors before they come off the old engine so the new one goes back in the same order.
Prime the oil system as far as your workshop's procedure allows before the first start. A dry turbo on a six-cylinder diesel is an expensive first five seconds.
The yard is at Andreas Meyer Straße 38, 22113 Hamburg. Call or WhatsApp +49 15510 030835, or email autowerkeengines@gmail.com, Monday to Friday, 9:00 to 16:00 CET. Shipping is 249 € per order. We are an independent seller, not BMW AG.