The head gasket is a seal that protects the car's cylinders by preventing coolant leakage and by keeping the coolant and oil from mixing. Inside a BMW, the head gasket sits underneath the cylinder head. If the BMW's engine tends to overheat, it can damage the head gasket. When replacing a damaged gasket, be prepared to drain your coolant system and undertake a major operation in removing all of the engine's components just to access the gasket.
Park the car, turn off the vehicle and pop the front hood.
Locate the negative battery cable which has a minus (-) symbol label and a black cable cord affixed to it. With a heavy-duty socket wrench, twist the bolt attached to the negative battery terminal to the left to remove. Wriggle the black cable from its end base from the terminal with needle-nose pliers to free.
Drain the cooling system; place a pan underneath the car's radiator unit drain plug. Turn the radiator's cap counter-clockwise to remove. Use an adjustable wrench to remove the mounting bolts from the clamp that secures the air intake hose. Remove the bolt by twisting it to the left from the radiator's timing belt.
Open the radiator's plug with the wrench, turning it counter-clockwise to loosen the plug and to allow the coolant to flows from the radiator into the pan. Re-tighten the plug after the coolant runs out.
Pour a 50/50 blend of commercial coolant liquid and lukewarm water inside the radiator, or refer to the BMW owner's manual to get the exact measurement.
Start the engine to allow the coolant mixture to flush for 15 minutes. Idle the engine after coolant has flushed. Drain the radiator again with a flush and fill kit purchased from a local auto store. Run the engine for 25 minutes, then let idle for 15 minutes.
Loosen the bolts that secure the distributor cap which is positioned next to the cylinder. Also remove the car's intake manifold bolt.
Access the cylinder head, which is located inside the internal combustion engine and positioned atop the cylinders on top of the cylinder block (it consists of a platform housing spark plugs and poppet valves). Remove its valve cover and unscrew its bolt with the wrench to remove. To make sure you are removing it correctly, loosen its bolts from outside the cylinder head by working your way inward. Once all bolts have been loosened, go back to the beginning to remove all the bolts.
Reach in its block to access and lift up the head gasket from inside. Use a putty knife to scrape any residue left underneath the head gasket.
Discard the old head gasket and replace with a new one. Position the new one inside the cylinder block. Replace all of the removed components and re-secure their bolts tightly.
