BMW 3 Owners & Service Manuals

BMW 3: Belt drive

Belt drive
Comparison belt drive B46 engine and B46TU/B48TU engines

  1. B46 Engine (transverse installation shown)
  2. B46TU/B48TU engines (transverse installation shown)
  1. Deflecting element
  2. Alternator
  3. Coolant pump
  4. Air conditioning compressor
  5. Ribbed belt
  6. Torsional vibration damper
  7. Belt tensioner

The belt layout is a single-belt drive where all ancillary components are driven by one belt.

Changing the belt guiding has help to save both material and space.

The length of the drive belt changes due to thermal expansion and ageing. So the drive belt can transmit the required torque, it must be continuously in contact with the belt pulley at a defined pressure. To allow this to happen, the belt tension is exerted by an automatic tensioning pulley mounted on the alternator; the pulley compensates for belt elongation over the full service life.

In case of incorrect assembly of the drive belt, the coolant flow through the coolant pump is either insufficient or non-existent; there is thus a lack of cooling. There is a risk of damage to engine components and engine damage


     Cooling System

     Split cooling

    Split cooling is a new development for the B46TU engine. This cooling concept is a modified version of which is already used in the N63TU2. The Split Cooling function uses the electrical Split Cooli

     Heat management module

    The heat management module replaces the characteristic map thermostat. Heat management module Electrical Split Cooling Valve (SCV) Coolant output towards the coolant pump Electrical actuator Rot


     Voltage supply for other high-voltage consumers

    The Electrical Machine Electronics supplies voltage not only to the electrical machine. The convenience charging electronics are directly connected with the Electrical Machine Electronics and ensure the voltage supply at high-voltage level to the electric A/C compressor and electrical heating. H

     General information

    Electronic control devices are installed in the vehicle. Electronic control units process data they receive from vehicle sensors, self-generate or exchange with each other. Some control units are necessary for the vehicle to function safely or provide assistance during driving, for instance driver

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