Engines
BMW N52 oil leaks: oil filter housing and valve cover gaskets
Oil on the engine of an N52 is common. Some leaks are messy. One of them can destroy your serpentine belt and much more.
Which cars have the N52?
The N52 3.0 straight-six was fitted from about 2004 to 2015 to cars like the E90 325i and 330i, E60 525i and 530i, E83 X3, E70 X5 3.0si and the Z4. It is smooth and reliable, with a few known leak points.
The oil filter housing gasket
The oil filter housing sits on the side of the engine. When its gasket hardens, oil drips onto the serpentine belt. Oil-soaked belts can slip, fray and get pulled into the front of the engine, which can damage the crankshaft seal. This leak should be fixed as soon as it is found.
The valve cover gasket
The N52 has a plastic valve cover. With age the gasket hardens and the cover can crack. Oil then leaks onto the exhaust side, which causes a burning smell and smoke from under the bonnet. A cracked cover should be replaced, not just resealed.
Other N52 checks
- Electric water pump and thermostat: these fail with age and can cause sudden overheating warnings.
- Lifter tick on cold starts.
- VANOS solenoids and their seals.
How we fix leaks properly
We clean the area, confirm exactly where the oil comes from, and replace gaskets with new OEM parts. On the oil filter housing we always inspect the belt and tensioner and replace them if oil has reached them. Fixing the gasket but leaving an oil-soaked belt only moves the problem.