Definition of discourse marker noun from the Oxford Advanced Learner's Dictionary
When an engine starts knocking, one of the first things a mechanic will check is the oil pressure. A warning light may come on in the car, and adding sufficient oil will solve the problem. Sometimes, a knocking noise is caused by loose torque converter bolts or a loose flywheel.
December 02, 2015. You enjoy listening to the purr of the engine as you cruise along the highway. When you hear some strange sound coming from under your hood, you may panic. A knocking sound can be worrisome, and here is what it might mean and what you should do. Knocking in your engine, also described as pinging, can mean one of several problems. Some may be easily fixed while others may indicate major damage.