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.

Index	Explanation	Index	Explanation
1	Vacuum hose to the engine mounts	2	vacuum line
3	Switchover valve	4	Air collector for intake air

Controllable engine mounts

Index	Explanation	Index	Explanation
1	Controllable engine mount, left	2	vacuum line
3	Controllable engine mount, right

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

E60	Idling with the vehicle stationary	No partial vacuum	Soft characteristics
E60	Vehicle moving	With partial vacuum	Hard characteristics
E8x, E9x	Idling with the vehicle stationary	With partial vacuum	Soft characteristics
E8x, E9x	Vehicle moving	No partial vacuum	Hard characteristics

Threshold values for switching over the engine mounts:

E60	Idling with the vehicle stationary	Driving speed less than 50 km/h
	Idling with the vehicle stationary	Engine speed less than 1500 rpm
	Vehicle moving	Driving speed greater than 50 km/h
	Vehicle moving	Engine speed greater than 1500 rpm
E8x, E9x	Idling with the vehicle stationary	Driving speed less than 15 km/h
	Idling with the vehicle stationary	Engine speed less than 1200 rpm
	Vehicle moving	Driving speed greater than 15 km/h
	Vehicle moving	Engine speed greater than 1200 rpm

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