BMW N55 engine report
BMW N55 · 335i (F30)
3.0 LPetrolInline-62012–2016
70/100
[good]
A quick everyday 335i, if the bearings and chain are sound
Worth buying, but only on the right car. A full record of oil changes at least every 10,000 km, an oil filter free of bronze flakes, and no chain noise when the engine starts from cold.
ExcellentGoodSolidRiskyAvoid
- Known issues
- 17
- Critical
- 4
- Sources
- 120
Verdict
Rod bearing failure is the risk that decides this car, because it is very common here and counts as a design weakness rather than bad servicing.
Have a specialist check for bearing wear and read the oil-change history before you agree a price. Timing chain wear is common as well. The oil pump fails only occasionally, but when it does it can starve the engine of oil. Seal and gasket leaks are to be expected, and the high-pressure fuel pump and injectors give out from time to time, so keep money aside for them. The turbo, the intercooler and the head gasket almost never cause trouble.
Specs
- Displacement
- 3.0 L2,979 cc
- Layout
- Inline-6
- Fuel
- Petrol
- Compression
- 10.2:1
- Production
- 2009–2021
- Chassis
- F30
- Fitted
- 2012–2016
Known issues
17 confirmed · sorted by severity
CriticalRod bearing failure
Connecting rod (big end) bearing wear or spun bearing, usually from oil starvation or extended oil-change intervals -- can destroy the engine if not caught early.
Symptoms
- Knocking Noise
- Warning Light
How often
Very common · Design weakness. Can destroy the engine if ignored. Not safely drivable.
Evidence
85 owner reports back this, confidence 50/100.
CriticalOil pump wear / sludge buildup
Oil pump wear or sludge accumulation (often from extended oil-change intervals) reducing oil pressure and lubrication.
Symptoms
- Warning Light
- Knocking Noise
How often
Occasional · Design weakness. Can destroy the engine if ignored. Not safely drivable.
Evidence
27 owner reports back this, confidence 50/100.
CriticalPiston ringland failure
Piston ringland cracking under high cylinder pressure/heat, common on tuned forced-induction engines.
Symptoms
- Power Loss
- Smoke (White/Blue/Black)
- Misfire
How often
Very rare · Design weakness. Does not normally destroy the engine. Not safely drivable.
Evidence
4 owner reports back this, confidence 50/100.
CriticalHead gasket failure
Head gasket failure, often preceded by overheating; can lead to a warped head or cracked block if not addressed.
Symptoms
- Coolant Loss
- Smoke (White/Blue/Black)
- Warning Light
How often
Very rare · Age-related wear. Does not normally destroy the engine. Not safely drivable.
Evidence
4 owner reports back this, confidence 45/100.
HighHigh-pressure fuel pump failure
HPFP wear or failure, sometimes shedding metal debris into the fuel system.
Symptoms
- Misfire
- Warning Light
- Hesitation
How often
Occasional · Design weakness. Does not normally destroy the engine. Not safely drivable.
Evidence
28 owner reports back this, confidence 60/100.
HighTurbocharger failure
Turbo bearing/shaft wear, oil seal failure, or surge damage, often linked to oil starvation or carbon buildup.
Symptoms
- Power Loss
- Smoke (White/Blue/Black)
- Whining Noise
How often
Very rare · Age-related wear. Does not normally destroy the engine. Still drivable.
Evidence
4 owner reports back this, confidence 50/100.
ModerateTiming chain stretch / guide wear
Timing chain elongates or plastic guides wear prematurely, causing rattle, incorrect valve timing, or in severe cases chain failure.
Symptoms
- Knocking Noise
- Cold Start Rattle
- Warning Light
How often
Common · Design weakness. Does not normally destroy the engine. Still drivable.
Evidence
49 owner reports back this, confidence 60/100.
ModerateWater pump failure
Water pump seal or bearing failure (mechanical or electric pump), causing coolant loss.
Symptoms
- Coolant Loss
- Warning Light
How often
Rare · Design weakness. Does not normally destroy the engine. Still drivable.
Evidence
14 owner reports back this, confidence 65/100.
ModerateExcessive oil consumption
Worn valve stem seals, piston rings, or a clogged PCV/oil separator system causing oil consumption above manufacturer spec.
Symptoms
- Oil Consumption
- Smoke (White/Blue/Black)
How often
Rare · Design weakness. Does not normally destroy the engine. Still drivable.
Evidence
8 owner reports back this, confidence 45/100.
ModerateDual-mass flywheel / clutch wear
Dual-mass flywheel wear causing rattle/vibration, often coinciding with clutch replacement interval.
Symptoms
- Excessive Vibration
- Knocking Noise
How often
Very rare · Expected maintenance. Can destroy the engine if ignored. Still drivable.
Evidence
6 owner reports back this, confidence 45/100.
LowOil leak from seals or gaskets
Valve cover gasket, rear main seal, or front main seal degradation causing external oil leaks.
Symptoms
- Oil Consumption
How often
Common · Age-related wear. Does not normally destroy the engine. Still drivable.
Evidence
40 owner reports back this, confidence 65/100.
LowFuel injector failure
Injector wear, sticking, or seal failure causing misfires, rough running, or fuel leaks.
Symptoms
- Misfire
- Rough Idle
- Fuel Smell
How often
Occasional · Age-related wear. Does not normally destroy the engine. Still drivable.
Evidence
21 owner reports back this, confidence 50/100.
LowThermostat / temperature sensor failure
Thermostat sticking open or closed, or temperature sensor drift, causing incorrect operating temperature.
Symptoms
- Warning Light
How often
Rare · Age-related wear. Does not normally destroy the engine. Still drivable.
Evidence
9 owner reports back this, confidence 65/100.
LowWastegate / boost actuator failure
Wastegate, boost control actuator, or diverter/blow-off valve failure causing boost leaks or inconsistent boost pressure.
Symptoms
- Reduced Power Mode
- Turbo Lag
How often
Rare · Design weakness. Does not normally destroy the engine. Still drivable.
Evidence
13 owner reports back this, confidence 50/100.
LowIntercooler failure or leak
Intercooler core cracking or pipe seal failure, causing boost loss.
Symptoms
- Power Loss
How often
Very rare · Age-related wear. Does not normally destroy the engine. Still drivable.
Evidence
4 owner reports back this, confidence 50/100.
LowVariable valve timing solenoid/actuator failure
VANOS/VTEC/VVT-style variable valve timing solenoids or actuators fail or clog, causing rough idle, rattle on start, or reduced power.
Symptoms
- Rough Idle
- Reduced Power Mode
- Warning Light
How often
Very rare · Design weakness. Can destroy the engine if ignored. Still drivable.
Evidence
6 owner reports back this, confidence 50/100.
LowEngine sensor failure
Crankshaft, camshaft, MAP, lambda/O2, or MAF sensor failure causing rough running, stalling, or incorrect fueling.
Symptoms
- Warning Light
- Rough Idle
- Misfire
How often
Very rare · Age-related wear. Does not normally destroy the engine. Still drivable.
Evidence
2 owner reports back this, confidence 45/100.
- Critical
- High
- Moderate
- Low
Rod bearing failurefrom 84k km
Oil pump wear / sludge buildupfrom 114k km
High-pressure fuel pump failurefrom 164k km
Timing chain stretch / guide wearfrom 80k km
Water pump failurefrom 113k km
Oil leak from seals or gasketsfrom 105k km
Piston ringland failurefrom 89k km
Head gasket failurefrom 97k km
Showing the 8 highest-impact of 17 dated issues. The rest are in the list above.
Buying checklist
0 of 15 checked
Sources
Updated 12 Sept 2026 · scoring v2.7
Behind this report sit 120 owner posts, forum threads and official records. Nothing gets on the list on one person's word. It takes a recall, or owners on separate platforms describing the same fault. The score then sets how often a problem turns up against the damage it does.