How to Install a Thermostat on a BMW 323ic

1. Remove the radiator hose from the thermostat housing by loosening the retaining clip that secures the hose onto the housing with the screwdriver. Pull the hose off the thermostat housing and hold it vertical so the antifreeze goes back into the radiator. Push the hose off to the side to make accessing the thermostat housing easier.
2. Remove the 10 mm bolts that hold the thermostat housing onto the intake manifold of the BMW with the wrench and then pull the thermostat housing off the intake manifold.
3. Remove the old thermostat and then place the new one into the intake manifold. The thermostat sits on a machined lip that is located below the level of antifreeze. The thermostat should be properly seated to ensure it works correctly.
4. Pull the old thermostat gasket off the intake manifold and place a bead of RTV gasket sealer in its place on the intake manifold. Place the paper thermostat gasket on top of the RTV gasket sealer. Place a small amount of RTV gasket sealer on the bottom of the thermostat housing and then bolt the housing back into place.
5. Place the radiator hose back onto the thermostat housing and secure the retaining clip into place.
6. Start the engine and allow it to warm up. Inspect for leaks where the thermostat housing is bolted to the intake manifold and where the radiator hose connects to the housing. If the radiator hose leaks, replace the retaining clip with a band clamp. If the area where the housing and the manifold bolts together leaks, tighten the housing bolts more.

DIY BMW 540I Thermostat

1. Slide the drain pan under the radiator petcock. Open the petcock and allow 2 pints of coolant to drain. Ensure that the drain pan is clean, so that you can reuse the coolant.
2. Loosen the hose clamp at the thermostat, using a screwdriver. Pull the hose off the thermostat. Unbolt the three retaining bolts on for the thermostat housing, using the appropriate socket. Remove the housing. Pull the thermostat out of the housing, or engine, if it doesnt stick to the housing.
3. Clean the gasket mounting surfaces, using the rubber scraper and rags. Install the O-ring on the thermostat housing. Insert the thermostat onto the engine, ensuring that the support bar on the thermostat is facing out.
4. Install the thermostat housing and tighten the bolts to 6 lb.-feet of torque. Refill the cooling system.