How to Distinguish Between Intake and Exhaust Camshafts in an Engine?
2 Answers
Methods to distinguish between intake and exhaust camshafts in an engine: You can observe the position of the screws and the belt on the camshaft. The intake camshaft usually has a camshaft position sensor installed at the front or rear, is longer in length, and has a signal disc at the tail. If it's hard to distinguish, it's okay to make a mark when disassembling, as they can generally be identified. Even if they look the same externally, there are letters indicating their function: 'I' stands for intake, and 'E' stands for exhaust. The camshaft is installed at the top of the cylinder head and functions to drive the intake and exhaust valves to open and close. Both the intake and exhaust camshafts are equipped with a drive wheel, which is directly driven by a chain or belt to rotate the camshaft. Some engines use a chain drive to rotate the camshaft, aiming to reduce the valve angle.
Distinguishing between the intake and exhaust camshafts of an engine is actually not difficult. With over a decade of experience in car tinkering, I always start by examining the engine layout. Simply put, in a dual overhead camshaft (DOHC) engine, the camshaft closer to the intake manifold is usually the intake camshaft, as it’s responsible for opening the intake valves to draw in the air-fuel mixture. The one near the exhaust manifold is the exhaust camshaft, tasked with closing the exhaust valves to expel burnt gases. I remember my first time working on a car—I visually confirmed their positions: the intake manifold typically connects to the air filter, while the exhaust manifold links to the catalytic converter. Tracing these connections will lead you right. Of course, some models have markings, such as 'IN' or 'EX' engraved on them. Beginners should always consult the manual or take photos for reference to avoid reversing them, which could cause engine vibration or valve damage—a real headache. After a few tries, it becomes second nature.
