General information (BMW 3 Series E46)

How to use the information in this chapter

This part of Chapter 2 describes the types of repair work that can be performed without removing the engine from the vehicle. If the engine has already been removed and disassembled as described in Part B, all previous disassembly operations can be ignored.

Keep in mind that while repairs to components such as the piston and connecting rod assembly can be performed without removing the engine from the vehicle, such procedures are not usually performed in isolation from other operations. Other engine components and parts usually require replacement and repair by this point (not counting cleaning of parts and oil channels). Therefore, all such operations are classified as major repairs, and their content is disclosed in Chapter 2B.

Chapter 2B describes the procedures for removing the engine from the vehicle and all repair procedures that can be performed after that.

Engine Description

General information

The M52TU and M54 six-cylinder engines have two overhead camshafts and are in-line. The engine is longitudinally mounted, with the transmission attached to the rear of the engine. The difference between the engines is that the M54 has a fully electronically controlled throttle valve, which is set to produce minimal pollution.

The exhaust camshaft is driven by a chain from the crankshaft (primary chain), and the intake - another chain from the exhaust shaft (secondary circuit). Hydraulic tappets are installed between the cams and the valves. Both shafts have seven supports, located in a cast housing, which is attached to the top of the cylinder head.



The crankshaft also has seven main bearings of conventional design with liners. The axial play of the crankshaft is limited by thrust bearings located on the 6th bearing.

The pistons are selected by weight. The upper head of the connecting rod is of the floating type, fixed from axial movements by spring rings.

The oil pump is driven by a chain from the crankshaft.

Valve timing regulators

All models are equipped with an automatic variable valve timing system, known as VANOS. The VANOS system regulates the phases of both the intake and exhaust camshafts independently of each other and is part of the engine management system. The phase control system has a hydraulic actuator. Powered by the engine lubrication system. The shaft phases are adjusted depending on the crankshaft speed, reducing the advance, i.e. opening the valves later, at low and high engine speeds. This improves engine control at low speeds and increases power at high speeds. At medium engine speeds, the advance increases (i.e. the valves open earlier), in order to increase torque and reduce exhaust gas toxicity.

Repair operations that can be performed without removing the engine from the car

The following operations can be performed without removing the engine from the vehicle:

• a) Removing and installing the cylinder head.
• b) Removing and installing the timing chain and sprockets.
• c) Removal and installation of camshafts.
• d) Removing and installing the pallet.
• d) Removal and installation of lower connecting rod heads, connecting rods and pistons.*
• e) Removing and installing the oil pump
• g) Replacement of power unit supports
• c) Removing and installing the flywheel/faceplate

* These procedures can, of course, be performed without removing the engine from the vehicle. However, for better access and to ensure cleanliness, they should be performed after the engine has been removed.

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