Bmw N55 common problems

So you just bought a N55 engine equipped bmw car and you are ready to squeeze some more power out of it and have the fun that this car can provide? Here are some common problems that car with the N55 engine has shown over the years with or without a software tune installed on the factory (ECU) (PCM) engine management system.

If you own a 135, 235, 335 ,435, 535, X1, X3, x4, X5, X6 or any other car with a manual (ZF S6-45) or automatic (ZF 6HP19 and ZF 8HP45) gearbox below you will find a list which we will update through time.

Common N55 Engine Problems Brief List :

  • Boost and Charge pipe braking or detaching from throttle or intercooler.
  • Valve Cover Oil Leak
  • Water Pump Failure
  • Leaking Oil Filter Housing Gasket
  • VANOS Solenoid Failure
  • High Pressure Fuel Pump Failure (HPFP) – Mostly older models
  • Fueling system insufficiency (Can not hold more than +- 500hp)

The boost pipes issue :

A lot of owners have reported problems with both of those pipes especially after a tune on the n55 platform.The pipe on the left side (charge pipe) is attached to the throttle with a small metal safety clamp which can not hold higher boost pressures and in some cases not even stock boost when the car gets too warm inside a race track or after hard use on the street.

Exactly the same thing can happen to the boost pipe which is connected directly to the intercooler and in that case you need to replace everything plus the o-ring seals inside it.We suggest the upgrades to be done with custom made aluminum pipes which are sold by a lot of companies as an upgrade for the N55 engine.

N55 Valve Cover and Gasket Leak Symptoms:

  • Low engine oil light
  • Burning oil smells, or smoke coming from valve cover area
  • Oil on spark plug threads

It is like bmw never learned anything from the n54 oil leak and not only issues which are giving hard times to most of the owners with higher mileage bmw cars.

Another issue that ties into the valve cover and gasket is the Positive Crankcase Ventilation Valve (PCV valve).A PCV valve uses the engine vacuum to pull any blow-by gases out of the crankcase, and is integrated into the valve cover. Higher pressures and fatigue of the PCV valve lead to eventual failure, and this is a fairly common issue with the BMW N55. Due to the fact you must remove the valve cover and gasket to access the PCV valve you may want to consider replacing your valve cover, and as always, the valve cover gasket should be replaced.


N55 Water Pump Failure

  • Engine overheating significantly – usually rapid over-heating once the pump fails
  • Cooling Fan running full speed (noisy)
  • Coolant boiling out of coolant cap
  • CEL DTC : 2E81, 2E82, 2E83, 2E84, 2E85, 377A

Problems with water pumps do not only affect the N55, but are a widespread problem among most Bmw engines. Water pumps are responsible for circulating coolant throughout the N55’s cooling system in order to cool engine temperatures. BMW uses electric pumps that are driven by a composite impeller, which do not have a very long lifespan. It is important to note – the thermostat is also a common point of failure. Due to the excessive labor to replace a water pump it is recommended you replace the thermostat along with the pump.

The longevity of these BMW water pumps may vary significantly, with failures commonly cited as early as 30-40k miles while others may last more than 120,000 miles. On average, if your original pump and thermostat last until 100,000 miles they are likely soon on their way out.

BMW water pumps typically do not show any symptoms before failure, but rather, fail quite suddenly. If the pump is slowly failing electrically, this can simply be tested by examining the coolant flow in the cooling system; a failing pump will not flow coolant at the intended pressure.


More details coming soon for the rest of the problems.

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