How to Replace a Volkswagen Thermostat

by Zyon Silket

Starting in the early 1980s, Volkswagen started selling the Jetta model, which came equipped with a liquid-cooled engine. In 1996, Volkswagen reintroduced the Volkswagen Beetle, and dubbed it "The New Beetle." In-between those two models, Volkswagen also introduced the Cabriolet and the Passat. All four of these models used radiator fluid, rather than air flow, to regulate the engine temperature. In this system, a thermostat is used to regulate the engine temperature; when the thermostat stops working, replacement is the only option for repair.

Drive the Volkswagen onto a set of ramps and place a wheel chock behind the rear tire.

Place a drain pan capable of holding two gallons of fluid under the radiator drain valve. Place a ΒΌ-inch ratchet drive into the drain plug and drain approximately two gallons of fluid out of the radiator--this lowers the fluid level below the upper radiator hose and prevents fluid from getting all over the engine. Set the fluid off to the side--it will be reused.

Follow the upper radiator hose to the location where the hose connects to the engine. Loosen the band clamp on the hose and pull the hose off the housing it connects to--this exposes the thermostat housing.

Remove the three bolts that secure the housing to the engine, using a 14-mm socket, then lift the thermostat housing off the Volkswagen engine. The 14-mm bolt is the most common-sized bolt for the Volkswagen thermostat housing, but its size may vary, depending on your model of vehicle.

Pull the old O-Ring off the thermostat housing and replace it with a new one. The housing does not use a traditional gasket; instead, it relies on the O-Ring to complete the seal.

Pull the old thermostat out of the engine and then place the new one into place. The thermostat has a large spring on one end (the end that sits inside the engine).

Place the thermostat housing over the thermostat and bolt it into place. If the old bolts are rusted or rounded over, use new ones.

Reconnect the radiator hose and secure it with the clamp.

Open the radiator filler cap located on the left side of the radiator. Drain the fluid back into the radiator slowly, allowing time for air to purge from the radiator. Close the cap once completed.


  • close Never work on the cooling system when the engine is hot, as you may suffer severe burns.

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About the Author

Since 2006 Zyon Silket has been writing for companies such as SEOWhat, L&C Freelancing and T-Mobile Wireless. He has extensive experience working in supervisory roles within the wireless and Internet technologies fields. Silket is pursuing a Bachelor of Arts in business management and network technologies at Lehigh Carbon Community College.

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