Opel Corsa B 1993–2000 Service and Repair Manual: Thermostat - removal, testing and refitting

Removal

1. Drain the cooling system, saving the coolant if it is fit for re-use.

Disconnect the battery earth lead and proceed as described under the relevant subheading.

1.2 litre models

2. Disconnect the radiator top hose from the outlet connection at the top of the water pump. This exposes the thermostat and it will be seen that it is retained by a snap-ring.

3. Prise the snap-ring free using a suitable screwdriver blade and then remove the thermostat from the pump outlet (see illustrations).

Remove the thermostat retaining snap-ring . . .

. . . and withdraw the thermostat - 1.2 litre model

1.3 and 1.4 litre models

4. Remove the camshaft toothed belt cover, which is secured by five screws.

5. Slacken the clip and detach the radiator top hose from the thermostat housing.

6. Remove the two bolts and detach the thermostat housing (see illustration). On later models the thermostat housing may not be accessible until the camshaft toothed belt back plate has been removed, if necessary remove the plate.

Removing the thermostat housing . . .

7. Remove the thermostat from its recess, noting how the projections on the thermostat fit in cut-outs in the recess (see illustration).

. . . and withdraw the thermostat from its recess - 1.3 litre model

1.6, 1.8 and 2.0 litre models

8. Slacken the clip and detach the radiator top hose from the thermostat housing (see illustration).

Slackening the hose clip at the thermostat housing (1.6 litre model shown)

9. Unbolt and remove the thermostat cover and extract the thermostat (see illustrations).

On 2.0 litre 16-valve models the thermostat is a bayonet fitting in the housing; release it by depressing it and turning with a pair of pointed-nose pliers.

Removing the thermostat cover . . .

. . . and the thermostat itself (1.6 litre model shown)

Testing

10. A rough test of the thermostat may be made by suspending it with a piece of string in a container full of water. Heat the water to bring it to the boil - the thermostat must open by the time the water boils. If not, renew it.

11. If a thermometer is available, the precise opening temperature of the thermostat may be determined and compared with the figures given in the Specifications. The opening temperature is also marked on the thermostat (see illustration).

Testing the thermostat

12. A thermostat which fails to close as the water cools must also be renewed.

Refitting

1.2 litre models

13. Refitting the thermostat is the reverse sequence to removal, but use a new rubber seal and install the thermostat with the arrow on the web pointing upwards. Refill the cooling system.

All other models

14. Refit in the reverse order to removal; use a new rubber seal on the thermostat (see illustration). Refill the cooling system.

Fitting a new seal to the thermostat