Yes most definitely. If you're not sure what you're looking for, have a mechanic check it out.....
A hole in the muffler would cause a knocking sound in your muffler. A loose exhaust pipe can also cause a knocking noise.
The noise is the teeth on the flywheel grinding on the teeth of the starter. Check to see if the starter is loose, this is the most common cause of that noise.
A bad transmission. The sound is from metal grinding on eachother.
Sounds like your problem is probably a loose heat-sheild or a loose exhaust. Have it checked.
loose exhaust pipe or muffler is most common
Check if muffler is loose, check if rear brakes are worn out & grinding
An exhaust leak could do that.
lifters are beginning to go. timing chain (if vehicle is equiped) may be coming loose. and or exhaust pieces are loose.
a dining sound could be lose nuts on the exhaust
Heat shields often corrode and become loose but they usually cause a tinny rattling sound. Eventually they fall off as witnessed by the dozens of them found along highways. Mechanics often remove them (with your permission) if they are loose, because they serve no purpose other than to protect the technician from a very hot catalytic converter that he/she knows not to touch anyway. A "knocking" sound, however, is more likely caused by a worn or broken exhaust hanger, allowing the exhaust system to bump the underside of the vehicle. Be sure the engine isn't causing the knocking sound, driving around a car with a knocking sound in the engine can cause MAJOR damage. Knocking from your undercarriage can also be caused by suspension components that have gone bad or are leaking fluid.
a loose or slipping belt
An exhaust restiction, like a clogged catalytic convertor