Buying a used BMW 4 Series F32, which engine should I choose?
The BMW 4 Series F32 is a good option for those looking for a premium rear-wheel-drive sedan with a dynamic driving experience, especially with the M Sport package. Our buyer's guide will help you understand which models to avoid, features, advantages, and points to watch out for when purchasing this model.
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Reliability by engine
420i and 428i pre-facelift (4-cylinder N20 engines)
The N20 engine is a 2-liter turbocharged gasoline engine with direct injection. The 420i versions use a detuned variant of the 328i engine. With a simple Stage 1 remap, power can reach over 250 horsepower, offering an attractive alternative for low-cost power.
Reliability and common problems
BMW N20 engines are often criticized for their reliability, with several recurring problems:
Timing chain: These engines have a tendency for their timing chain to stretch, and the plastic guides can break. It is important to pay attention to any unusual noises, especially when the engine is idling.
Turbocharger: The turbocharger's intake pipes and vacuum lines are prone to cracking. These cracks can lead to power loss and misfires , thus affecting vehicle performance.
Excessive oil consumption: This problem can appear even before reaching 150,000 km, or even 100,000 km. The main causes include:
- Faulty PCV (oil vapor recirculation): A faulty PCV is often the simplest and least expensive cause to repair. It may be necessary to replace either the diaphragm alone or the entire valve cover.
- Worn valve stem seals: Worn valve stem seals can also lead to excessive oil consumption. This is often manifested by blue smoke coming from the exhaust when accelerating after idling for a while.
- Oil leak at the rocker cover gasket: The N13 and N20 engines are also prone to oil leaks at the rocker cover. To detect these leaks, simply remove the engine cover and inspect the top of the engine.
- In the most serious cases, excessive oil consumption may be due to wear of the piston rings and cylinders of the engine block, then requiring a complete replacement of the engine block or a rebuild.
Coolant leaks: Coolant leaks can also occur, often at the rear of the engine block. It is therefore essential to regularly inspect for any signs of fluid leaks around and behind the engine.
418i after facelift (3-cylinder B38 engine)
The B38 engine is significantly more reliable than the previous model. Although a few incidents of premature timing chain wear or thermostat replacement have been reported, these problems are rare and not considered recurring.
430i after facelift (4-cylinder B48 engine)
The B48 engine represents a significant improvement in reliability compared to its predecessor, the N20. Engineers have successfully resolved the timing chain issues that plagued the previous model.
As a result, the B48 offers more stable and durable performance, reducing the risk of mechanical failures. The improvements made to this engine allow owners to enjoy a more reliable and worry-free driving experience, a significant advantage over previous models.
Coolant leaks from two places are sometimes mentioned in connection with this product:
- Coolant leak from the upper engine hose
- Leak through the oil filter housing
435i (6-cylinder N55 engine)
The BMW 435i with the N55 engine is generally considered reliable.
However, the intake system can become clogged if the vehicle is driven too slowly. Furthermore, as is the case with many BMW gasoline engines, oil leaks can occur at the valve cover, oil filter housing, and lower crankcase.
440i and m440i (6-cylinder B58 engine)
The 440i , often nicknamed the " German 2JZ " because of its ability to significantly increase its power with minimal modifications (a simple reprogramming can easily reach 400 horsepower), is probably the most reliable model among the 4 Series petrol models , and the one we recommend, both for its reliability and driving pleasure.
Although these cases are rare, it is possible that the B58 engine may suffer from fouling if the vehicle is used too moderately.
BMW 418d, 420d and 425d pre-facelift (4-cylinder N47 engine)
The BMW N47 engine, which powers the BMW 4 Series F32, has seen a significant improvement in reliability compared to previous versions. Initially, this engine suffered from frequent timing chain problems, which was a source of concern for many owners.
In 2011, BMW undertook a series of significant modifications to improve the reliability of this engine. These adjustments led to a considerable reduction in timing chain problems.
Between 2013 and 2015, BMW continued to make further improvements to the N47 engine. These modifications were designed to further optimize engine reliability, and by 2015, timing chain issues had been completely eliminated . Thanks to these efforts, the N47 engine became significantly more reliable, offering BMW 4 Series F32 owners a more serene and worry-free driving experience.
BMW 418d, 420d, 425d after facelift (4-cylinder B47 engine)
With the 2017 facelift (LCI) of the 4 Series, BMW replaced the old N47 engine with the B47 unit in the diesel versions. Found under the hood of the 418d, 420d, and 425d , this 2.0L four-cylinder engine is renowned for its fuel efficiency. In terms of reliability, it addresses several weaknesses of the N47, particularly regarding the timing system.
Unlike its predecessor, the B47 has a better-designed timing chain that is less prone to premature failure. However, it is still recommended to listen for any unusual noises when starting or when the engine is cold, although problematic cases are less frequent. Rigorous maintenance with regular oil changes is essential to preserve the engine's longevity.
In terms of turbocharging and fuel injection, these engines are generally reliable, provided that excessive city driving is avoided , as this could clog the EGR system and the DPF (diesel particulate filter). As with many modern diesels, regular highway driving is recommended to minimize these risks.
Both the ZF8 automatic and manual transmissions are durable if properly maintained. Changing the transmission fluid every 100,000 km is a useful precaution, although not officially recommended by BMW.
BMW 430d and 435d (6-cylinder N57 engine)
The BMW 430d and 435d of the F32 generation are often cited as models of reliability within the 3 Series range. Equipped with the 3.0L inline six-cylinder engine ( N57 ), these diesel versions offer solid performance while maintaining reasonable fuel consumption. Overall, the N57 has earned a good reputation for its robustness and longevity, provided it is properly maintained.
That said, particular attention should be paid to the timing chain . Although the risks are lower compared to some older BMW engines, it is crucial to listen carefully for any unusual noises when starting or at low engine speeds, especially on models with over 150,000 km. A metallic clunk or irregular noise could indicate premature wear, requiring costly repairs.
Apart from this point, these engines do not suffer from any major chronic problems. The turbochargers are reliable, provided the maintenance recommendations are followed (regular oil changes with quality oil). The 8-speed ZF automatic transmissions, which are generally fitted to these models, are also known for their smoothness and durability, but preventative maintenance (transmission fluid change around 60,000-100,000 km) is advised to avoid any premature wear.
In summary, the 430d and 435d F30 are excellent choices for those looking for a high-performance and durable BMW, provided that the condition of the timing belt is carefully checked at the time of purchase and that rigorous maintenance is followed.
Enhance your BMW 4 Series F32 with our premium accessories
Your BMW 4 Series F32 combines elegance and sportiness — and with our dedicated accessories, you can make it even more exclusive. Euro Racing Parts offers everything you need to modernize, personalize, and restore your interior .
Install a CarPlay/Android Auto module to enjoy a modern and seamless multimedia system:
Transform its look with a complete body kit — front lip, diffuser, spoiler, LED Angel Eyes and black grilles:
And breathe new life into the interior with our replacement parts : console buttons, carbon fiber inserts and gear selector:
All our products are compatible with the 4 Series F32 , guaranteed for 1 year , and delivered free of charge from our store.
In conclusion, which models should be avoided and which should be preferred?
Models to avoid: BMW 418i (3-cylinder engine, low power), 420i and 428i from 2011 to 2015 (phase 1)
Preferred models:
- BMW 430i from 2015 onwards (phase 2),
- BMW 430d, 435d phase 1 and phase 2
- BMW 435i and 440i
For each model, we recommend not relying solely on the "long-term" service intervals provided by BMW, but rather changing the oil every 10,000 km for petrol engines and 15,000 km for diesel variants . This will minimize wear on the timing chain and variable valve timing system. Also, be sure to use the oil viscosity recommended by BMW to maximize the lifespan of your engine.
When considering a new purchase, prioritize a model with a clear history .
Regarding the sportier models 435i, 440i and m440i , these are more subject to mistreatment by their previous owners than to intrinsic reliability problems.
Inspect tire wear: signs of overheating, front tires worn on the sides (synonymous with fast cornering), heavily worn rear tires (skidding), blue brake discs (heavy braking) and the seller's comments (respecting turbo warm-up and cool-down times).
