How to Replace a Jetta 1.8T Thermostat


1. Remove the radiator hose from the thermostat housing by using a screwdriver to loosen the band clamp that secures the hose to the housing. With the clamp loosened, pull the hose off the thermostat housing. Lift the hose vertically to drain any fluid back into the radiator.
2. Turn the two bolts that hold the thermostat housing onto the Jetta's intake manifold, then pull the thermostat housing off the intake to expose the thermostat.
3. Pull the old thermostat out of the intake manifold and discard it. Set the new thermostat into the hole in the intake manifold.
4. Pull the old thermostat gasket off the intake, then place a bead of RTV silicone gasket maker around the bottom edge of the thermostat housing to create a seal. Allow 15 minutes for the RTV silicone to cure.
5. Place the thermostat housing back onto the intake manifold and bolt it into place.
6. Slide the radiator hose back onto the thermostat housing and secure the hose by tightening the band clamp.