Common problems on the BMW N55
The N55 is the successor to one of the most legendary European engines of all time. It doesn’t matter if it’s a 135i or a 335i, these cars are some of the most solid and adjustable out there.
However, while it can be considered much more reliable than its big brother, the N55 still has a few skeletons in its closet that you should watch out for, whether you’re an owner or a potential buyer.
VANOS solenoid failure
Since their introduction to BMW models in 1992, VANOS systems provide variable valve timing to BMW engines for increased performance and smooth operation. As with any complicated part, VANOS. The N55 is not exempt from this problem. VANOS solenoids can become worn or dirty and prevent oil from passing through them. The flow of oil to the cam gears is what allows the timing to be adjusted, and when it slows down or stops, it can cause a number of problems for the car. Some of these symptoms may include rough idling, low RPM driving, loss of power, and decreased fuel economy. These problems are often accompanied by a check engine light and occasionally the car goes into a limp mode.
High pressure fuel pump failure
Although more common in early engines, all N55 owners should know the symptoms of a failing high pressure fuel pump (HPFP). An O-ring separates the fuel pump between the fuel half and the oil half, and when this O-ring degrades over time, it can cause a significant loss of fuel pressure.
As you can imagine, when the engine can’t get the right fuel, bad things happen. This problem can present itself as problems starting the car, hesitation when accelerating, stopping,. Fortunately, even though it will need to be replaced, there are a few things you can do to extend the life of your HPFP. Using high-quality oil with additives can prevent accelerated O-ring wear, and keeping your vehicle healthy with regular changes can also help.
Water pump failure
The water pump is one of the most vital parts of your engine, it keeps the coolant circulating and prevents the engine from overheating. The N55 has an electric water pump, unlike most cars where the pump is driven by the engine. These electric pumps have a higher probability of failure than a traditional one, and problems can worsen over time without proper maintenance.
Water pump failure is most often seen in engine overheating, which can lead to costly repairs. You can also often hear the cooling fans working overtime to compensate for the pump, and the pump will often make a shrill sound when the pulley or bearings loosen. Coolant vapor and its sweet smell are your last warning sign before things turn catastrophic if they haven’t already. To avoid this, the cooling system should be regularly serviced and you may want to replace the pump at 60,000-90,000 miles as the pump will eventually fail.
Oil leaks
There are two main points that the N55 loves to leak. One is the oil filter housing gasket, which becomes less effective over time. Of course, oil wears out all parts, but a particularly weak part like this gasket is more susceptible to total failure and oil leaks. This leak is often found in the drive belt, which can cause serious problems such as premature belt wear or even belt breakage, which can (in rare cases) lead to total engine failure. The other big culprit is the valve cover and its gasket. A minor leak here may be safe to drive on and cause little or no damage for a short period of time, but these parts are relatively inexpensive and not replacing them for a small leak can allow the leak to grow and eventually allow let the oil rise. reaching the engine mounts and even the belts.
Loading pipe problems
The N55’s factory charge pipes are made of a plastic material that is initially resistant to heat and pressure, but with constant heat cycling and increased pressure, this plastic can begin to crack and eventually filter out When this happens, you will notice a significant loss of power and throttle response, as well as the car possibly entering a limp mode state. This problem is much more common with increased boost levels, but it can still happen on a completely stock engine. So, even with increased stock, a reinforced plastic or even metal charge pipe can be a smart investment to prevent future boost leaks.
Is the N55 worth it?
The N55 was essentially BMW’s answer to the unreliability of the N54, and is a much more robust engine. However, it’s still a complicated, high-tech, high-performance engine that needs to be treated as such. The earlier N55 engines have a bit more issues, but still these engines will run great and well with proper owner maintenance.
When you own or buy a car with an N55 engine, it is important to take the car in for an expert inspection to make sure the engine is in good condition. With the right owner, these engines can be as reliable as any.
Service and inspections N55 at Alex’s Autohaus
Alex’s Autohaus is your premier destination for BMW and European car service in the Salt Lake Valley. Our ASE certified technicians will keep your Bimmer running smoothly and know what to look out for on your specific vehicle. With our help, we can keep your N55 buttoned up and your car on the road. Call or schedule an appointment with us online today!
