Audi VW Thermostat Assembly - Mahle Behr 03L121111AC

Product Information

Thermostats are a simple device which regulates coolant flow through the engine. When cold it will stay closed, stopping coolant flow and helping the engine warm up faster. Once up to temperature, it will open and allow normal coolant flow and maintain proper engine temperature. Always install with the 'jiggle pin' bleed valve at 12 o'clock when possible.

For many applications, multiple temperature ratings are available. These ratings denote when the thermostat opens, and in extreme climates different temperature ratings can be used to assist the vehicle in maintaining proper temperatures. In very hot desert climates for instance, a lower temperature rated thermostat may be preferred.

There are two types of thermostat failures:

Thermostat stuck open (most common): Coolant will flow through the engine constantly from cold, preventing the engine from reaching operating temperature. Usually this means a rich mixture resulting in poor fuel mileage and potential catalytic converter damage.

Thermostat stuck closed: If the thermostat is stuck closed it will restrict flow into the engine resulting in an overheating condition, resulting in potential catastrophic engine damage.

• Overheating engine
• Engine not reaching optimal running temperature
• Radiator fan not engaging

About Mahle

Mahle began in 1920 when pistons made of heavy gray cast iron were being used in internal combustion engines for automobiles and there was a need for a new design. The Mahle brothers countered this trend by producing light-alloy pistons at their small, newly established company however the technology was still finicky and problems come up frequently. They soon determined that they needed to come up with a solution to keep dirt and dust out of the engine so they eventually developed air and oil filters as well. Their perseverance paid off and the light-alloy pistons began to take over the market. Today, half of all automobiles produced worldwide contain MAHLE components. MAHLE offers an extensive range of parts for everyone including pistons, cylinder liners, piston ring sets, bearings, assemblies, valves, valve train components, and air, oil, fuel, and cabin air filters. Their catalog and online database of aftermarket engine components is an indispensable reference.

MAHLE Aftermarket is the world’s leading manufacturer of more than 100,000 OE and aftermarket parts, including MAHLE gaskets, engine bearings, turbochargers, thermostats, pistons and piston rings, valves, engine air and fluid filters, heavy-duty engine components, and rotating electric components such as starters, electric motors, and alternators.