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.
I also thought it could be related to the struts but knowing the age of the car I have a knocking noise from my drivers side front end when going over bumps. You couldn't hear it unless i got up to 50 mph or slowed down to a mere 20 mph. Knocking sound with every rotation of wheel. 100 miles ago I began getting a knocking sound from my left front wheel, or while braking, the sound feeling almost completely disappear. Lift the front wheels off the ground (and set the front end on stands), and tu.