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.
The cam phasers on the 3V 4.6L engines can also tend to be noisy, producing a light knocking sound at idle. This is normal, Ford says. But if the noise is excessive (under 1,200 rpm) or there are cam-related fault codes, the problem may be a bad variable cam timing phaser that needs to be replaced.