Removal and installation the air filter (BMW 3 Series E30)

Removal

Unscrew bolt "1".

Open the quick release latches (arrows) and remove the air filter cover.

Remove the filter element.



Loosen the nuts (arrows) securing the air filter housing.

Remove the fastening -H.

Unscrew nut "1" of the intake system support.



Disconnect the outside air hose "2" and the warm air hose "1", having first completely loosened the clamps "S".





Disconnect the engine crankcase ventilation hose "E", the hose of the valve metering additional air in the forced idle mode, and also the vacuum hose at the bottom of the air filter housing.

Remove the air filter housing.

Installation

Connect the engine crankcase ventilation hose, the hose of the valve metering additional air in the forced idle mode, and the vacuum hose at the bottom of the air filter housing.

Place the air filter housing, apply the mounting ring and screw it on.

Secure the intake system support to the bracket.

Connect the outside air hose and the warm air hose, securing them with clamps.

Insert the filter element.

Place the cover so that arrows "2" and "3" in Figure W-2014 point towards each other.

Screw on the air filter cover and secure with quick-release fasteners.

Checking the intake air heating

Heating of the intake air depends on the temperature and is regulated by the air damper in the air intake. If there is a defect in the heating system, the following malfunctions may occur:

• Violations of the idle mode during the warm-up phase.
• Transient disturbances.
• Insufficient power, maximum speed is not reached.
• High fuel consumption.

Checking the position of the air damper

The position of the air damper is controlled through the inspection window "2" in the air intake "3".

When the engine is running cold, the damper should open the warm air channel "4" so that warm air flows from the exhaust manifold to the air filter.

As the engine warms up, the air damper gradually closes the warm air channel and simultaneously opens the outside air channel.

When the engine reaches operating temperature, the warm air channel is completely blocked. Only outside air enters the engine. Otherwise, check the membrane box.

Checking the membrane box

Check the reliability of the fastening of the vacuum hoses between the membrane box and the temperature regulator and between the temperature regulator and the intake manifold.

When bending the hoses, check for cracks and damage; if necessary, replace damaged hoses.

Disconnect the hose "5" from the temperature regulator "6" at the bottom of the air filter housing and check the operation of the air damper by sucking it in with your mouth. If the damper opens, clean the holes "E" and "F" of the temperature regulator (drawing W-2015). If necessary, replace the temperature controller.



If the air damper remains closed, replace the diaphragm box.

At the service station, a vacuum pump with a connected pressure gauge is used to check the membrane box. The pump is connected to the hose "5" and thus creates a vacuum at the membrane box. Up to a vacuum of 70±10 mbar, the warm air channel must remain closed, starting from a value of 140±10 mbar, it must be open. In the removed position, the adjustment lever of the membrane box at a vacuum of about 300 mbar must be completely recessed and the vacuum must not decrease.

(The original material is located on the website «BMWman»)