Thermostat — removal, checking, and installation (VW Lt 28)

1. A faulty thermostat can cause the engine to overheat or significantly lengthen its warm-up period. It also affects the operation of the heater.

2. Drain the coolant through the radiator drain plug until its level drops below the contact surface of the thermostat housing (in total, you will have to drain approximately 3 liters of coolant).

3. Unscrew and remove the 2 mounting screws. Pull out the thermostat housing cover just enough to allow the thermostat to be pulled out of its socket in the cylinder head (see photos).





4. To check the operation of the thermostat, immerse it on a thread in a container of water. Heat the water and use a thermometer to determine at what temperature the thermostat begins to open. The thermostat must be replaced if it sticks in the open or closed position, or if its opening temperature is not within specifications. Never replace a faulty thermostat if there is no replacement available. It is better to leave the system without a thermostat for the time being.



5. The thermostat is installed in reverse order. Check that the contact surfaces of the thermostat housing are clean and install a new O-ring.

[The information is posted on this website: VWmanual.ru]