BMW engines, particularly in older models like the 1998 328iS, are known for developing oil leaks around valve cover gaskets and oil filter housing gaskets.

The cooling systems on older BMWs can be problematic, often due to failures in the water pump, thermostat, or radiator, leading to overheating issues.

The Variable Nockenwellen Steuerung (VANOS) system, which adjusts camshaft timing, can fail or become noisy in older BMW models, affecting engine performance.

The crankcase ventilation system can become clogged or fail, leading to issues such as vacuum leaks, poor engine performance, and increased oil consumption.

Ignition coils in this model are prone to failure, which can cause misfires, rough idling, and poor acceleration.

The MAF sensor can fail or become dirty, leading to incorrect air-fuel mixture readings and causing rough idling, stalling, or poor fuel economy.

Faulty oxygen sensors can lead to poor fuel economy, increased emissions, and a decrease in engine performance.

Over time, the timing chain and its associated components can wear out, leading to rattling noises, poor engine performance, and potential engine damage if not addressed.

Due to aging gaskets and seals, oil leaks are common in older BMW engines, such as the 1999 BMW 328iS.

The cooling system, including the water pump, radiator, and thermostat, is prone to failures, leading to potential overheating issues.

The Variable Valve Timing system (VANOS) can experience problems, leading to poor engine performance and rough idling.

A faulty crankshaft position sensor can cause starting issues and poor engine performance.

Ignition coils can fail over time, leading to misfires and reduced engine efficiency.

A dirty or faulty MAF sensor can cause poor engine performance and fuel economy.

Aging hoses and connectors can cause vacuum leaks, leading to rough idling and poor performance.

Over time, the timing chain and its components can wear out, leading to potential engine damage if not addressed.