Automatic air damper — removal, installation, adjustment (Opel Astra F)

To check the idle speed and the quality of the fuel mixture, you will need a tachometer and an exhaust gas analyzer. After removing the housing, you must install new sealing rings.

Removal

Disconnect the negative battery terminal, air cleaner hoses and remove the air box.

Note the location of the bimetallic spring housing alignment marks for ease of installation and, if necessary, make additional marks, then unscrew the three screws and remove the bimetallic spring housing. Slide it aside, being careful not to strain the hoses or wiring.



Remove the three screws securing the choke housing to the carburetor body, remove the throttle assembly, being careful not to bend the drive rod.

Remove the bimetallic spring housing for replacement if necessary, in this case proceeding as follows, otherwise omit the following three steps.

Note the location of the air damper cooling hoses with automatic control for easier installation, then disconnect the hoses. There may be a coolant leak, so it is necessary to clamp the hoses or hang them with their ends up.



Disconnect the wiring from the air damper heater and remove the bimetallic spring housing.

[The source is on the online website: Opelbook.ru]

The cooling jacket can be removed from the bimetallic spring housing by unscrewing the central bolt. Remove the sealing rings from under the bolt head and from the cooling jacket rim.

Installation

Begin installation by positioning the choke assembly into the carburetor body, making sure its lever engages with the operating rod. Tighten the three screws.

Check and, if necessary, adjust the choke clearance and fast idle adjustment cam position as follows.

Connect the bimetallic spring to the air damper lever, install its body and the damper body in the position as noted during removal, then tighten the screws.

If required, install the cooling jacket onto the spring housing, new O-rings, and connect the cooling hoses and choke heater wiring.

Installation is carried out in the reverse order of removal, taking into account the following.

If the cooling hoses were disconnected, check the coolant level.

Check and, if necessary, adjust the fast idle speed as described in this section.

Adjusting the air damper clearance

After removing the bimetallic spring housing, the procedure is as follows.

Press the choke lever all the way clockwise and hold it in this position with a rubber band.

Press the throttle lever to its fully open position and measure the air gap between the bottom of the throttle and the wall of the secondary chamber diffuser. It should be within specification.



Adjust the air damper clearance, if necessary, by bending segment (2). Fig. 4.31. If the clearance is too small, increase the clearance (B) using a screwdriver. If the clearance is too large, decrease the clearance (B) using pliers.



If further adjustment is not required, reinstall the bimetallic spring housing as described previously.

Fast Idle Adjustment Cam Location

After removing the bimetallic spring housing and setting the air damper clearance ("A" in Fig. 4.32), continue working as described below.



Open the throttle valve, then close the choke valve by lightly pressing the choke lever with your finger. Close the throttle valve.

Check to see if the fast idle speed adjustment screw is touching the highest step of the cam.



If adjustment is required, first check that the air damper return spring is installed correctly, then adjust with lever (2).

Install the bimetallic spring housing as described previously.

Fast Idle Speed Adjustment

Note: An accurate tachometer and exhaust gas analyzer are required to perform the adjustment.

Check the mixture quality and idle speed. The idle speed must be exactly within specification before checking or adjusting the fast idle.

The engine should be at normal operating temperature, the tachometer connected according to the manufacturer's instructions. Then the work is carried out in the following order.

Set the adjusting screw to the highest step of the cam.

Start the engine without touching the accelerator pedal and check that the idle speed is correct. If adjustment is required, stop the engine and perform the operations below.

Remove the special safety cap from the fast idle speed adjustment screw - (please take into account national laws).

Check if the adjusting screw is set to the second high position of the fast idle speed adjustment cam, then start the engine again without pressing the accelerator pedal.



Turn the adjusting screw with a screwdriver until the fast idle speed is set to specification.

If the cooling fan starts during these operations, stop adjusting and continue operation only after the fan stops.

After completing the adjustment, turn off the engine and disconnect the tachometer.

Install a new safety cap onto the fast idle adjustment screw.