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BMW N20 Reliability

The N20 engine is an outstanding power plant capable of withstanding extensive performance tuning. However, it does present its own set of challenges.

Even though N20 is among one of the most well-developed types of BMW engines, there should still be some considerations for N20 reliability.

One major issue was a timing chain fluke that affected thousands of early models; this issue has since been resolved and, otherwise, the N20 is generally reliable. Here are the most searched topics on N20 reliability:

Timing Chain

The N20 engine has only experienced one significant issue that caused a class-action lawsuit; nevertheless, most drivers find it to be reliable. Other issues may occur less frequently but can still incur substantial maintenance and repair expenses for owners.

Timing chain failure is the single greatest source of N20 reliability issues, since this component coordinates all parts of an engine in terms of when to open valves for gas inlet and combustion, inject fuel, or ignite spark plugs.

As it uses a chain instead of a belt, timing chain systems require more maintenance as they may wear down over time and fail altogether. A whining noise from the engine when under light revs or acceleration could indicate trouble; excessive scoring or scratching on engine surfaces or excessive slack in timing chains could also indicate issues.

These issues may be costly, but they don’t occur as frequently as other issues with an N20 engine like oil leaks or defective ignition coils. With proper care and regular maintenance, your N20 motor should last many thousands of miles reliably without needing repairs – but it is wise to remain alert for these potential trouble spots so as to avoid ending up at a repair shop or worse yet, on the side of the road!

Ignition Coil

Oil leaks or ignition coils may be faced in N52 usage. So, this malfunction can be remembered for N20 reliability.  Ignition coils are compact electrical transformers designed to convert low on-board vehicle voltage into high ignition voltage needed to fire spark plugs. It does this through its primary winding which has few turns of wire while its secondary winding has many.

Ferromagnetic coil cores also play a significant role here, by intensifying the magnetic field produced by secondary windings and thus helping reduce energy losses due to eddy currents and magnetic saturation.

Dependent upon its intended application, an ignition coil may need to produce up to 25,000 volts at peak demand – this depends on factors like spark plug electrode gap width and fuel/air ratio as well as other considerations.

Most modern cars no longer employ distributors, instead opting instead for coil-on-plug (COP) ignition coils which sit directly atop each spark plug, making the replacement much simpler compared to replacing individual spark plugs directly. COP designs are significantly simpler to service and essentially follow the same steps when installing replacements plugs themselves.

These parts should typically be changed every 50,000 miles; however, their lifespan could decrease quicker if your engine has been modified or tuned. As with its predecessor, the N52, rod bearing failure can occur, resulting in tapping noise as piston rods strike against the crankshaft and scrape the engine case. Furthermore, a VANOS actuator (an electronic solenoid that regulates variable valve timing) may also malfunction and fail resulting in engine block scrap.

VANOS Actuator

The VANOS system (Variable Nockenwellen Steuerung) from BMW allows them to optimize torque and power across its speed range by changing cylinder duration via helix gear actuator and control valves. DME monitors engine RPM and load to adjust its position accordingly and make necessary changes accordingly.

There may be some problems related to the VANOS system in BMW engines, even for N20. This should also be mentioned for N20 reliability.

System can sometimes produce a “tick” noise due to actuator seal wear-and-tear, with low RPM range power loss or torque being affected as a result of this wear and tear. Unplugging the electrical connector on VANOS solenoid may help.

Some TSBs suggest replacing the helix-gear actuator and camshaft position sensors, however this rarely proves effective at eliminating codes or solving an issue. O-ring wearout on helix gear actuators often causes oil pressure leakage past the piston, leading to hydraulic jamming during full advance or retard modes; there are improved seal kits containing Viton O-rings available as solutions.

Failure of the DME to adjust helix-gear actuator and/or control valves correctly can create other issues. This can cause it to set incorrect camshaft position sensor signals that trigger codes on its own. A diagnostic procedure involving DME, scope and special tool set to lock crank and camshaft can help identify this issue and pinpoint it quickly.

Valve Cover/Gasket

At the top of your engine sits the valve cover – an external hard plastic or metal shield which shields engine components such as the valve train from debris. Most modern valve covers have gaskets to provide an efficient seal; should any part fail, oil may escape through this breach in its protection.

Low engine oil levels increase friction among your car’s components, potentially leading to overheating and engine fire over time. Furthermore, leaky oil may drip onto hot engine components like the fuel intake or cylinder head and cause an unpleasant burning oil smell within the vehicle as well as smoke in its exhaust when running.

If your valve cover gasket begins to wear out, professional mechanics should replace it immediately. While the part itself is fairly affordable, labor costs associated with installing and replacing it could be considerable depending on how easily accessible it is – in some cases this might involve dismantling turbo plumbing and intake components for access.

Overall, for N20 reliability it can be said that the N20 engine is reliable; however, that does not preclude mechanical issues from cropping up over time. Therefore, regular maintenance and follow-up service appointments will help minimize common BMW issues as your engine ages. Once these precautions are done properly, you won’t have any sad experience with N20  engines even in the long term.

Juan Gibson

Juan is an automotive engineer and an avid car enthusiast. He has over 15 years of experience in the car industry. In my free time, I write blog posts about cars, models and etc.

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