Automatic air cleaner temperature control - testing

Fuel and exhaust systems - carburettor models / Automatic air cleaner temperature control - testing

1 Unclip and remove the vacuum unit and inlet pipe but leave the vacuum pipe connected (see illustration).

4.1 Air cleaner vacuum unit

2 Suspend a thermometer in the flow of air through the inlet duct then start the engine.

Between -20°C and + 20°C, the control flap in the unit should be a maximum of 2/3rds open to admit hot air from the exhaust manifold.

Above 20°C, the control flap must close the hot air supply (see illustration).

4.2 Air cleaner load and temperature control diagram – 1.05 and 1.3 litre

A Temperature regulator B Intake pipe with thermostat C Vacuum unit

3 The control flap movement can be checked by sucking on the vacuum inlet.

4 With the engine running and inlet air temperature above 20°C, disconnect the vacuum hose from the vacuum unit. The control flap should fully open within a maximum of 20 seconds.

5 If the control unit does not operate correctly then renew it, together with the temperature sensor (see illustration).

4.5 Upper view of air temperature sensor - 1.3 litre

6 Refit the vacuum unit and inlet pipe.