*Tools and Materials*:
1. New Thermostat (OEM recommended)
2. Coolant (G12 or equivalent)
3. 5mm Allen Key
4. 10mm Socket Wrench
5. Pliers
6. Funnel
7. Rags/Towels
8. Safety Goggles
9. Gloves
Procedure
1. Preparation
- Let your engine cool down completely to avoid burns.
- Engage the parking brake and turn off the engine.
- Locate the coolant reservoir. It's usually a translucent plastic tank near the front of the engine bay.
- Remove the coolant reservoir cap carefully to release pressure in the cooling system.
2. Locate the Thermostat Housing
- The thermostat housing is usually at the upper part of the engine, attached to the cylinder head.
- On the Passat, it's near the front of the engine, below the intake manifold.
- It has two coolant hoses connected to it.
3. Drain Some Coolant
- Place a catch pan under the radiator drain plug, usually located at the bottom of the radiator.
- Open the drain plug to let some coolant out until the level is below the thermostat housing.
- Tighten the drain plug once you have drained enough coolant.
4. Remove Thermostat Housing Bolts
- Using a 5mm Allen Key, loosen and remove the two bolts that hold the thermostat housing to the cylinder head.
5. Pull Out Thermostat Housing
- Carefully pull the thermostat housing away from the cylinder head, taking note of the orientation of the old thermostat for reinstallation.
- Be cautious as there may be some residual coolant inside.
6.Remove Old Thermostat
- Lift out the old thermostat from the housing.
- Inspect the thermostat for any signs of damage, wear, or build-up.
7. Clean Thermostat Housing
- Clean the thermostat housing and the mating surface on the cylinder head. Remove any debris or old gasket material.
8. Install New Thermostat
- Place the new thermostat in the housing with the correct orientation (usually with the spring side facing the engine).
- Ensure the thermostat is seated correctly and the jiggle valve (if present) is positioned upward.
9. Reattach the Thermostat Housing
- Position the thermostat housing back onto the cylinder head, aligning it with the mounting holes.
- Insert and tighten the two bolts you removed earlier.
10. Refill Coolant
- Open the coolant reservoir cap.
- Using a funnel, slowly pour in the required amount of coolant until the reservoir reaches the "Full" or "Max" mark.
- Remember to use the specified coolant type (usually G12 or equivalent) for your Passat.
11. Check for Leaks
- Inspect the thermostat housing and hoses for any leaks. Tighten any loose connections if necessary.
12. Start Engine and Test
- Close the coolant reservoir cap.
- Start your Passat and let it run for a few minutes.
- Monitor the temperature gauge to ensure it operates within the normal range.
13. Top Up Coolant
- Once the engine has cooled down, check the coolant level again and top up if necessary. Make sure the level is between the "Min" and "Max" marks.
*Note*: Be cautious when handling hot coolant and ensure proper disposal of old coolant according to local regulations. If you encounter any difficulties or uncertainties during the process, consult a trusted mechanic or refer to the vehicle's repair manual.
