N55 Problems To Look Out For

"A summary of all the common problems experienced on the N55 engine"

The engine is highly reliable, but as with any engine design, there is a list of common faults that can crop up. Being aware of these faults can help you to anticipate and mitigate any damage that they may cause.

This article highlights several common problems with the N55 engine, such as oil leaks, water pump failures, PCV valve issues, injector problems, and carbon build up on the intake valves.

In general terms, the more recent engines had fewer problems as causes were identified and dealt with by design.

However, I must emphasize that these issues and resulting problems can often be avoided or mitigated if detected early enough and addressed promptly.

Regular maintenance and inspections are crucial for preventing these problems from turning into more severe and costly repairs.

Common problems and issues on the N55 Engine

• High Pressure Fuel Pump problems (HPFP) early pumps often failed, even some later ones still had issues despite revisions.
• Timing chain rattles - due to stretching and fatigue the timing chain can degrade and eventually fail, many problems are avoided if this is spotted early on and dealt with.
• Boost pipe leaks - failed connections, split pipes and hoses and degradation can lead to loss of boost or intermittent boost problems.
• Oil Leaks, Valve cover gasket, oil filter housing gasket, and oil pan gasket can all leak oil, which can cause a fire hazard. Keep an eye out for signs of oil seeping out and get them repaired promptly.
• Electric water pump can fail, causing cooling issues and potential overheating. Keep an eye on coolant levels and get any leaks investigated and repaired.
• Wastegate arm or actuator can wear out, leading to turbo rattle and Boost issues. Address any rattles before they escalate into a bigger problem.
• PCV (crankcase valve) can lead to high oil consumption issues. If you notice the engine is consuming a lot of oil, the PCV could be the culprit.
• Injector problems can occur around 50,000 miles. Get them checked for efficiency and consider replacing them around this mileage.
• Carbon buildup can occur on the intake valves due to direct injection, which can hamper airflow and cause power loss. Get it inspected and professionally cleaned to prevent buildup from becoming an issue.

Please watch our video which covers the main N55 Problems. Be sure to keep up with our latest YouTube content and subscribe. This video goes into more detail on the issues mentioned in this article.

High Pressure Fuel Pump problems (HPFP)

One common issue that some models have is with the high-pressure fuel pump. Initially, the high-pressure fuel pump used on these models was the same one used on its predecessor, the N54, which had numerous problems and issues.

Although there have been revisions to the high-pressure fuel pump over the years, even some of the more recent versions are still subject to failures and problems.

Therefore, it is advisable to check if the warranty has been extended in your area and to speak with your local dealer if you experience any issues.

Such issues can lead to rough running, misfires, or even a complete stall of the engine.

Timing chain Problems

It is also important to note that timing chains, being made of metal, will stretch and flex over time due to the abuse they undergo, especially if you are a heavy-footed driver (let's face it you are driving an N55).

Consequently, timing chains have been known to stretch or fail completely.

If you own a BMW with an N55 engine, there are a few common problems and issues to be aware of related to the timing chain.

If you hear a rattling noise from the timing chain area on the side of the engine, it is important to have the timing chain checked thoroughly, as there could be an issue with the tensioner.

Rattling noise on startup or idle: A worn or stretched timing chain may cause a rattling noise when the engine is started or idling. This is because the chain is not properly tensioned and is slapping against the timing cover or other components.

Misfiring engine: A worn or stretched timing chain can also cause the engine to misfire. This is because the chain is not properly synchronizing the timing of the valves and pistons.

Power loss: A worn or stretched timing chain can also cause the engine to lose power. This is because the chain is not properly transferring power from the crankshaft to the camshafts.

Check engine light: A worn or stretched timing chain may also trigger the check engine light. This is because the engine computer has detected a problem with the timing system.

After you remove the plastic covers and quick prod and poke around would expose any excessive play (the timing chain should be tight).

When replacing the timing chain, it is usually recommended to replace the tensioner at the same time.

It is also important to stick to the recommended service intervals or even better, go for more frequent servicing, as letting the timing chain deteriorate can lead to catastrophic problems.

Boost pipe leaks

These engines run on high boost, and as a result, the boost pipes that connect to the intercooler, turbo, and intake are subjected to high pressures.

When removed and refitted you are almost guaranteed to suffer from a leak at some point in the future on older higher mileage engines.

These pipes are often prone to splitting or failure at the joints, causing boost leaks. If you experience a boost leak, it is likely due to a connection issue.

You should check the connections around the intercooler, which is typically the weak spot.

Upgrading the boost pipes is a wise move, particularly if you have tuned the car and are expecting higher pressure to go through the system into the engine.

Oil Leaks

While oil leaks are not very common in the N55 engine, there are a few weak spots that are worth keeping an eye on.

Oil leaks can result in low oil pressure if not monitored, which on the N55 can cause serious issues.

So where do you look for the typical oil leaks?

The valve cover gasket and the oil filter housing gasket are known to weep oil, and the oil pan gasket at the bottom of the engine is also a potential weak spot. If the oil pan gasket starts to fail, it may begin to seep oil, which can be a problem as any loss of oil is a concern.

If the oil gets onto the exhaust, it can be a fire hazard. You will usually notice the oil dripping onto the hot exhaust and smoking, which signals the potential danger.

Keep an eye on these areas and if there are signs of oil seepage, it is best to get them resealed and repaired to avoid causing any other issues down the line.

Electric water pump problems

It is important to constantly monitor the temperature of your N55 engine, if something goes wrong the temperature can climb quite quickly and reach damaging levels.

If you notice any temperature fluctuations, such as the engine not warming up properly or overheating to the point where it needs to cool down, it may be a sign of an issue with the electric water pump.

It is crucial to address this problem promptly as excessive heat can lead to further problems with the engine.

Electric water pump failures can also occur and should be monitored closely to ensure the engine stays properly cooled. You might notice it taking longer to warm up, or starting to run hotter than usual, which, in the absence of other obvious reasons could indicate a problematic water pump.

The N55 engine boasts an electric water pump, which is a smart and efficient design. It allows for better engine control over cooling and quicker engine warm-up.

However, there is a potential for cooling leak problems, which can lead to a buildup of coolant and air bubbles within the system.

This can cause the engine to overheat or create hot spots within the engine. If you notice the coolant level dropping without a clear explanation, it's best to investigate the issue.

Any coolant leaks around the engine should also be addressed to prevent further problems. The cause of the leaks could be a split hose, a bad connector, or a bad seal.

Wastegate Arm or Actuator Can Wear Out

Another potential issue to keep an eye out for is a rattling noise from the turbo's wastegate, which may indicate that it is wearing out and in need of replacement.

The wastegate arm or actuator can become worn over time due to the heavy workload it endures. If you detect a rattle, it is important to have it checked and repaired before it develops into a larger problem.

Moreover, if you notice any changes in the Boost, it could be a red flag, but this is often missed as these engines are known for their power, even a significant reduction in power may not be immediately noticeable.

PCV (crankcase valve) can lead to high oil consumption issues.

The PCV, or positive crankcase ventilation valve, is responsible for regulating the pressure inside the engine crankcase.

If it becomes clogged or fails, it can cause excess pressure to build up inside the crankcase, which can lead to oil leaks and increased oil consumption.

If you're experiencing high oil consumption on your N55 engine, it's definitely worth having the PCV checked and replaced if necessary. It is usually down to a tiny split in the diaphragm or mount.

Whilst you are at it, its worth thinking about fitting an oil catch can between the PCV and the intake.

Injector problems can occur around 50,000 mile

Injector problems are common with the N55 engine and typically arise around the 50,000-mile mark.

Bear in mind these are running at very high pressures, so even minor fluctuations in spray pattern or flow rate will have a big impact on performance.

It's important to have the injectors checked for efficiency, and if the mileage is approaching 50,000 miles, it's worth considering replacing them.

It's also a good idea to evaluate the overall fuel system and potentially upgrade it in conjunction with other tuning modifications.

Carbon Build Up Issues.

The N55 engine is a direct injection engine, which means that carbon buildup on the intake valves is common.

Without fuel spraying on the back of the valves, carbon can accumulate and hinder airflow, leading to decreased engine power.

If you suspect that carbon buildup is affecting your engine's performance, have it inspected by a professional who can use a camera to check the valves or remove the intake for a closer look.

While DIY sprays can help minimize carbon buildup, they are not as effective as professional walnut blasting or chemical cleaning processes.

The rate at which carbon accumulates depends on how the car is driven, with high-speed driving over long distances causing less buildup than frequent short journeys.

Many factors contribute to carbon buildup issues on the N55 engine.

The N55 engine is a powerful and efficient engine, but it does have its fair share of problems. However, if these issues are detected early enough, they can be easily resolved, and the engine can continue to perform at its best.

We encourage N55 engine owners to keep a close eye on their engine's performance and address any issues promptly.

To Improve N55 Reliability

Foremost among the concerns is the charge pipe system, often prone to troubles. To steer clear of problems, the initial modification you should prioritize is upgrading to an all-metal charge pipe.

For those keen on a more comprehensive solution, consider investing in an all-metal Turbo to Intercooler pipe.

Evolution Racing's offering is a standout choice known for its quality and performance. By switching to these metal components, you're pre-empting and avoiding potential issues down the road.

Another vital aspect to pay attention to in your quest to prevent problems is the oil cooling system.

Consider the installation of the Mosselmann Oil Thermostat Housing and the CSF upgraded oil cooler.

These mods will help to ensure that your engine's oil stays within the optimal temperature range, improving its durability and ability to withstand the rigors of spirited driving.

By focusing on these preventive measures in the charge pipe and oil cooling departments, you're effectively safeguarding your N55 from future hassles and ensuring a smooth and reliable driving experience.

If you have experienced any problems with your N55 engine or have any feedback to share, we invite you to comment below or join our forum.

Our community is dedicated to helping N55 engine owners get the most out of their engines and share their experiences. Together, we can ensure that our engines perform at their best and avoid any potential issues in the future. We are not here for profit, but to share knowledge and a passion for cars - especially the N55.

This article is flagged for an update, so please pass on specific tips below that I can include. All articles, and content was written by me, Waynne Smith TorqueCars founder. Some outlines are just too general so I appreciate your feedback and suggestions. This entry was filed under BMW. You can leave a response below or join our forum to discuss this article and car modification in detail with our members.

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