BMW 340i Buying Guide
The BMW 340i is a popular choice among driving enthusiasts who just need a little more space! Its rear-wheel drive layout, B58 3.0-liter inline-six turbocharged engine, and strong performance make it a unique offering in the saloon segment. However, like any vehicle, it has its own set of potential issues and considerations. This guide covers the key things to know before buying a BMW 340i, including common problems and essential information for buyers.
Engine and Performance
The 340i is equipped with BMW's B58 engine, a highly regarded powerplant known for reliability and performance. Producing around 335 horsepower, it delivers strong acceleration and a satisfying driving experience. However, there are a few things to watch out for:
Coolant leaks: The B58 engine can be prone to coolant leaks, if you're experiencing a coolant loss, or a car that you view has a "Coolant Low" message - you will need to investigate further. Problems with the coolant reservoir cap seals can bleed coolant slowly, whereas if the leak is heavy, check the charge-cooler hasn't been punctured.
Charge pipe: Whilst the charge pipes aren't as notorious as the N55, it is always worth considering an upgrade especially if you plan to increase the boost. Typical issues with Charge Pipes can cause low boost, or erratic boost. JXL Recommends - MMX Charge Pipe Kit
Oil filter housing: Quite a common problem with the B58, upon servicing the Oil Filters have a chance of sticking, and not coming out cleanly. This results in a longer time to change (or more expensive labour if you've taken it to a garage) - change your oil frequently (12,000 miles, or 6-8,000 miles if the car is driven hard)
Transmission
The 340i comes with either a ZF 8-speed automatic or a 6-speed manual transmission. Both are generally reliable, but there are some concerns to be aware of:
ZF automatic transmission: While smooth and quick, the automatic transmission can experience issues with shifting if not properly maintained. Regular fluid changes (every 60,000-80,000 miles) are recommended to keep it running smoothly.
Manual transmission: The 6-speed manual is robust, but the clutch can wear out prematurely, especially if the car has been driven aggressively. Check for clutch slipping or difficulty shifting gears during a test drive. If a new clutch is required, we recommend the Performance Clutches DMF Clutch Kit, which can handle much more torque than the standard unit. JXL Performance recommends: Performance Clutches DMF Kit - F30/F31/F32/F33/F36
Suspension and Handling
The 340i strikes a good balance between comfort and sportiness, but its suspension components can wear out over time, especially on cars that have seen spirited driving or track use.
Rear differential bushings: These bushings are prone to wear, leading to excessive movement and noise. Inspect the bushings during a pre-purchase inspection or when buying a higher-mileage model.
Shock absorbers: Over time, the shock absorbers can lose their effectiveness, especially if the car has been lowered or modified. Listen for knocking sounds or excessive body roll during cornering.
Interior and Electronics
BMW interiors are known for their quality, but the 340i tech can present some issues, particularly with the infotainment system and electronics.
iDrive system: The iDrive infotainment system may experience software glitches or screen freezing. Ensure the system is up to date with the latest software version to avoid issues.
Electronic sensors: The 340i has a number of sensors that can malfunction, including the parking sensors and tire pressure monitoring system. Ensure that all electronic systems are functioning properly when inspecting the car.
Potential Maintenance Costs
Owning a performance car like the 340i comes with higher maintenance costs than a standard vehicle. BMW parts and labor can be expensive, especially for things like brake replacements, suspension work, and engine repairs. Make sure to budget for regular servicing, including oil changes, brake fluid flushes, and transmission fluid changes.
Check out our 340i Maintenance Guide Here!
Final Considerations
Before purchasing a BMW 340i, it’s important to get a full service history and ensure that the vehicle has been well-maintained. Check for any signs of modifications, as these could impact the longevity of the vehicle, especially if tuning or aftermarket parts have been added without proper care.
For buyers considering performance upgrades or repairs, it’s essential to know that the 340i is highly tunable, but modifications can increase wear on key components. If you plan to tune your car, consider upgrading critical parts like the charge pipe, chargecooler, and exhaust system to support higher power levels safely.
Final Notes
For a detailed look at tuning options and how to get the most out of your BMW 340i, check out our Tuning Guide. To ensure your car stays in top shape, refer to our Maintenance Guide, which covers everything you need to know about keeping your 340i running smoothly.
At JXL Performance, we specialize in tuning parts, maintenance kits, and expert advice for the BMW 340i. Whether you’re looking to enhance performance or keep your vehicle in top condition, visit our website today to explore our full range of products and services.