[skpatel1975]

I have a 2009 328i coupe 6-speed RWD. Engine is done at 90K miles. Looking for a replacement engine. All the VIN decoders say mine is a N52K engine. Looking for insight what the difference is and compatibility between N52 engines.

[Matrix6048]

The N52K engine underwent minor modifications in September 2006.
Modifications were made in following areas:

• Cylinder head cover
• Camshafts
• Crankshaft
• Stem diameter of exhaust valves increased to 6 mm instead of 5 mm
• Torsional vibration damper
• Crankcase ventilation
• Hot-film air mass meter (HFM)
• Throttle valve
• Digital motor electronics

[Jros]

Keep your maf, throttle body, harness, coils, valve cover if you swap in an older N52.
Maf on yours may be digital if you run MSV80 ecu, and throttle body connector is different.

I am currently running an N52B30 in a car that was born with an N52B25K engine with no problems at all, self swapped in a weekend so it was not very hard to do.

Mine comes from a 330I with automatic transmission, but my car is a 6sp- in that case watch out for the crank pulley counterweight (smaller for manual), and the oil pan that is different between auto and manual (it fits slightly harder for the auto one, slightly bigger). Obviously the flywheel must be from the old motor.

i did not, but you could swap the oil pan from your old engine to get rid of the oil return for the ccv, i just capped it on mine because i am using N52K valve cover that incorporates the ccv system oil return too.