Dipstick Tube
A metal guide tube inserted into the engine block that houses and routes the engine oil dipstick.
The dipstick tube is a long, narrow metal pipe bolted to the engine block or oil pan that guides the oil dipstick down into the oil reservoir. It ensures the dipstick is routed safely away from hot exhaust manifolds and moving belts, allowing the driver to check the oil level safely.
The tube typically seals into the engine block using a rubber O-ring or a press-fit connection. Because it is exposed to constant heat and engine movement, the bracket holding the dipstick tube can crack, or the tube itself can rust or break off, especially in salty winter climates.
A cracked or loose dipstick tube can create a vacuum leak on engines that use crankcase vacuum (PCV systems) to manage emissions, leading to a rough idle or check engine light. It can also allow oil to splash out under high crankcase pressure or let dirt enter the engine.