Take it to a garage and have it put up on a lift for an inspection. It must have been a big rock!
Check the heat shield on the catalytic converter
what engine?
Sounds like your lifters are bad and might need ajusted or changed, it could be your cam not looping.
if it sounds like the knocking is coming from the bottom of the engine i would bet it was the rods or rod bearings may be worn. if the knocking is on the top ,then i would have the lifters and or the rocker arms checked.
Knocking as opposed to pinging or ticking, usually means seriously worn bearings of some sort. Time for an overhaul.
get a new trany or rebildit cuz its going out unless the knocking is from moter it might be timing
Purple martins are fairly noisy, chirping and making sounds that have been described as chortles, rattles, and croaks.
Sounds like you have big problems, sounds like it has been run low on oil, and or the oil pump quit working, and you wont be driving the car much longer,it sounds like rods knocking, which means new engine time .
The rattle you are talking about sounds like what we in the auto industry call "Pinging and Knocking" this can be caused by using low octane gas, engine timing is out of adjustment and or a few other engine tune up issues. If the rattle feels like it's only when giving it gas going up a hill where the engine is really working it could also be crack shaft bearings or connecting rod bearings that are about to give up the ghost. Big bucks.
Sounds like a piston hitting the cylinder head. A lifter will usually tick, but a piston will sound more like this knocking noise.
it sounds like the tranny reverse is gone and you have to replace the entire tranny
what caused knocking sounds for me was a pully on the serpentine belt that was attached to the power steering pump. the pump gasket busted which in turned damaged the pully. If you have a lift it is not too hard to replace. Doing while you're vehicle is on stands is a nightmare. its about a 650 fix at a mechanic...