Many different auto parts make up your factory BMW 635csi engine. Its main part is an engine block, incorporating pistons that pump up and down. These pressurize the mix of air and gas pushed into the engine by your fuel system. Your engine block contains everything thanks to a top-mount cylinder head that seals the area, helping to prevent gas loss. The intake valves and exhaust valves in the head make sure the engine has the right airflow and fuel quantity. They also regulate exhaust fumes. Your camshaft keeps the valves opening and closing in time with other parts. Your spark plugs ignite that blend of fuel and air; combustion occurs, releasing power. Your crankshaft converts it to rotary motion. Your driveshaft and transmission work together to transfer that movement to your wheels and tires, making them turn. All the while, an engine oil pan mounted on the bottom of your engine, also known as an oil sump, stores any motor oil used in lubrication. Many other parts make everything fit together correctly, too. They range from gears and rings to sprockets and bearings and more. Eventually, though, even high-quality OEM BMW engines wear out, and you'll start to have engine trouble. Signs and symptoms include your Check Engine light coming on, stalling, idling or acceleration problems, reduced fuel efficiency, and even problems starting up at all. Luckily, you can order the best BMW 635csi engine and replacement parts for your repair job here online. Browse what we have to offer and place your order today we'll ship directly to your door!