Engine Mount: Description and Operation

Controllable Engine Mounts

Controllable engine mounts
The 4-cylinder engines are fitted with controllable engine mounts. The controllable engine mounts achieve the following:
- They insulate the car body from vibrations as well as possible when the vehicle is at a standstill and idling
- They prevent 'bouncing' when the vehicle is being driven on poor road surfaces ('bouncing' = 'dancing' of the engine mass on the engine mounts)

Deployment of the controllable engine mounts:
- E60: N46B20O2 (Rest of World = RoW) and N43B20O0
- E8x, E9x: N43B16O0, N43B20U0 and N43B20O0

NOTE: The N43 has been developed for the European market.

The N43 with direct fuel injection will only be available in ACEA (ACEA: Association of European Automobile Manufacturers).

Brief description of components
The following components are described:
- Switchover valve for engine mount
- Controllable engine mount

Switchover valve for engine mount
The switchover valve for engine mounts is attached to the air collector for intake air. The DME activates the switchover valve. The activated switchover valve opens and releases the partial vacuum to the engine mounts.







Controllable engine mounts







The switchover valve applies a partial vacuum to the engine mounts or switches the partial vacuum off. Depending on the application, soft characteristics or hard characteristics are set at the engine mounts.
The partial vacuum is generated by the vacuum pump on the engine. The partial vacuum is fed to the engine mounts through hose lines.

System functions
The following system functions are described:

Activation of the controllable engine mounts







Threshold values for switching over the engine mounts:







NOTE: Both threshold values must be met.

Both the threshold value for the driving speed and for the engine speed must be met.

Notes for Service department

General information

NOTE: Controllable engine mounts in the E8x and E9x only for the N43.

The stratified charge in the lower engine speed range means that the direct-injection engine has increased irregular rotation. This irregular rotation decreases as the engine speed rises.
No liability can be accepted for printing or other errors. Subject to changes of a technical nature.