Car Model Guide/ Engines/ N52

N52B25 / N52B30

The safe choice of the range. Port injection means no carbon service and no high-pressure fuel system; what it does instead is leak oil from every gasket and eat a water pump.

Configuration	I6, naturally aspirated, magnesium-aluminium block	Displacement	2996 cc
Fuel	petrol	Injection	port
Shared components	oil filter housing · electric water pump

Cars using this engine

Variant	Chassis	Body	Years	Power	Risk	Good buy
323i	E90	sedan	2005–2007	177 PS	R2	€4,050
323i	E91	wagon	2005–2007	177 PS	R2	€4,300
323i	E92	coupe	2006–2007	177 PS	R2	€4,650
325i	E90	sedan	2005–2007	218 PS	R2	€4,750
325i	E91	wagon	2005–2007	218 PS	R2	€5,050
325i	E92	coupe	2006–2007	218 PS	R2	€5,450
325i	E93	convertible	2007	218 PS	R2	€5,350
328i	E90	sedan	2006–2011	234 PS	R2	€5,150
328i	E91	wagon	2006–2012	234 PS	R2	€5,450
328i	E92	coupe	2006–2013	234 PS	R2	€5,950
328i	E93	convertible	2007–2013	234 PS	R2	€5,750
330i	E90	sedan	2005–2007	272 PS	R2	€5,600
330i	E91	wagon	2005–2007	272 PS	R2	€5,950
330i	E92	coupe	2006–2007	272 PS	R2	€6,450
125i	E82	coupe	2008–2013	218 PS	R2	€7,000
125i	E88	convertible	2008–2013	218 PS	R2	€7,400
130i	E87	hatchback	2005–2011	265 PS	R2	€7,000
130i	E81	hatchback	2007–2011	265 PS	R2	€6,800

Engine and component issues

Electric water pump and thermostat failureelectric water pump€500–€800

Overheat warning with little notice, coolant temperature swinging, sometimes an immediate limp home. The electric pump's controller fails. It's a wear item with a service life, not a fault.

Check: Age and receipts matter more than symptoms, it usually gives no warning. Treat a car past 120,000 km with no pump history as owing €600.

CoolingcommonPartly detectableevidence: documented90–150k km

Cold-start lifter tick and VANOS rattleN52B25 / N52B30€150–€900

Sewing-machine tick from the top of the engine for the first seconds after a cold start. Hydraulic lifters drain down overnight, or the VANOS unit's internal bolts loosen.

Check: Listen at cold start. A tick that fades within 5–10 seconds is normal for this engine and not worth chasing; one that persists once warm is not.

EnginecommonDetectable at viewingevidence: documented100–250k km

Oil filter housing gasket leakoil filter housing€300–€600

Oil pooling on the subframe, oil on the serpentine belt, drips on the driveway. The gasket between the filter housing and the block fails. Oil then lands on the belt, and a belt that shreds can be drawn into the front crank seal.

Check: Put the car on a lift. Check the belt itself for oil contamination. An oily belt is the version of this fault that ends badly.

EnginecommonDetectable at viewingevidence: documented90–170k km

Valve cover gasket leakN52B25 / N52B30€250–€500

Burning oil smell after a drive, oil residue down the exhaust side of the block, occasionally smoke from the bay. The gasket hardens with heat cycles. Standard age-related failure rather than a design fault.

Check: Look along the exhaust side of the head for wet oil and baked residue on the manifold heat shield.

EnginecommonDetectable at viewingevidence: documented90–160k km

Eccentric shaft sensor leakN52B25 / N52B30€250–€450

Oil seeping from the Valvetronic sensor on the side of the head; in the worst case oil tracks into the wiring. The sensor's seal hardens.

Check: Look at the intake side of the head for a wet sensor body and oil tracking down the loom.

ElectricaloccasionalDetectable at viewingevidence: documented100–200k km

Chassis, gearbox and body issues aren't listed here. They depend on which car the engine is fitted to. Open a variant page for the merged list.