Common Issues on E46 BMWs

The E46 generation of the 3-Series BMW was sold in North America from 1999 to 2005. The platform offered a wide range of vehicles including wagons, coupes, sedans, and convertibles in both rear-wheel and all-wheel drive, with a variety of four- and six-cylinder engines.  

This era also saw the introduction of the legendary E46 M3, which has become highly desirable in the years since it went out of production.

Overall, the E46 generation was pretty reliable. Some of this can be attributed to the relative simplicity of these cars, especially in comparison to modern BMWs. With that said, there are a few common problems that are seen in this era. With some examples being over 20 years old, these issues are more prevalent.

In this article, we are going to go over the most common issues seen on E46 3 Series BMWs.

Oil Filter Housing 

On inline-6 engines of this era, the oil filter housing is located on the top of the engine, next to the intake manifold (driver’s side) at the front. Countless heat cycles and years of operation cause the gasket to harden, which leads to leaking. If the leak is severe, you will notice oil on the front of the engine block on the driver’s side around the housing. Replacing the seals in the housing will fix this issue.

VANOS Issues

VANOS is BMW’s variable valve timing system, and it was first introduced on the E36 platform in the early ‘90s. By the time the E46 went into production, VANOS systems were commonplace on many BMW engines. The VANOS system dynamically controls the timing of the intake and exhaust valves, leading to improved drivability and performance across the RPM range.

VANOS issues typically present as rough running, excessive noise, and a noticeable loss of power at certain RPMs. VANOS systems incorporate moving parts and gaskets which can wear out over time and will need to be replaced.

Throttle Body Actuator

This issue is prevalent in the S54 engine. The S54 utilized individual throttle bodies (ITB), which control the intake of air into each cylinder individually. The ITBs are controlled by a single rod and actuator. The actuator can run into issues or fail altogether, requiring replacement.

S54 Engine Bearings 

This issue is seen on the E46 M3. The high-performance nature of the S54 inline-six engine puts a lot of stress on engine internals. Unfortunately, the engine bearings will wear out and need to be replaced at around 60k miles.

Combi Valve Problems

The combi valve is part of the crankcase vent system. Inside the valve, there is a diaphragm that can tear and begin to leak. If this happens, the car can throw lean faults, have drivability issues, and emit a hissing noise from the engine bay.

Cooling System Leaks 

The plastic components in the cooling system on E46 BMWs are prone to becoming brittle and cracking, allowing coolant to make its way out of the cooling system. The resulting loss of coolant can lead to the engine overheating, which can cause catastrophic engine failure.

Cold Weather Crank Vent Kit

If your car originated in a warm state but now lives in a place that regularly sees colder temperatures, upgrading the Crankcase Ventilation system to a cold-weather kit is a good idea. The cold climate kit protects against condensation that can cause the piping to freeze and crack. If this happens, the car will have vacuum leaks and performance issues.

Window Regulators 

Window regulators are responsible for moving the windows up and down when they are activated by the motor or window crank. On E46 BMWs, they are prone to issues. Lack of maintenance, poor design, and delicate components all contribute to failure.

When a regulator fails, the window can become stuck, misaligned, or make strange noises when moving up and down. Luckily, this issue is more of a nuisance than a danger. Replacing the regulator will restore the functionality of the windows.

Have problems with your E46? Stop in at Alex’s Autohaus!

Whether you’ve owned your E46 for years or just picked one up as a project, the BMW experts at Alex’s Autohaus are here to help. Our technicians use factory diagnostic equipment and OEM parts on all our repairs, ensuring your car runs like it’s supposed to. Give us a call or schedule an appointment online today!