Car is making constant loud knocking noise when idle?

well it could be any number of things. I would first think of motor or tranny mounts. If the problem is in the motor, it will cost a good bit to have fixed. Just remember, KISS, keep it simple stupid. Good rule of thumb when working on cars.

You probley have no concept how long you have been working 4 quarts low.in case you examine the spec.you may locate that it quite is all it takes.The engine would have a undesirable rod from loss of lucubration witch skill an engine replace. some questions,is the engine leaking any have been?the clarification I ask if there are not any leaks and that automobile is easily maintained ( because it seems such as you do) it is not smoking or oil interior the coolant .Did the station that did the final oil replace ignore the oil. Now which you have oil interior the engine examine that the filter out is sealed and that drain plug on the oil pan isn't dripping..you will see drops of oil under the motor vehicle if leaking. seems ordinary that a automobile lost 4 qt of oil very quickly..examine for provider announcements or remembers too. in case you prefer an engine get a rebuilt.it is greater low-priced to place in a rebuilt engine then to repair the single interior the motor vehicle, good success

Knocking noises are never a good thing. You don't have to commit to any repairs and you are free to get as many opinions and estimates as you want - but you really need to have an experienced technician give this a listen and you'll have a much better idea of how serious (or minor) this noise is.

From the description in your question, my first guess would be either a cracked flex plate or a main bearing - neither of which is a minor repair.

Check, or have checked, the torque converter bolts that hold the converter to the flywheel. When under load it wants to move away from the flywheel and cause a knocking sound. Another possibility is to pull each spark plug wire with a pair of insulated nylon pliers while at idle and making the noise. If the noise stops on one particular cylinder, better check the connecting rod and/or rod bearing. You might have had a rod bolt snap or loosen and now the extra clearance to the crankshaft is making the noise.

possible problems:

1)bad spark plug thats not firing correctly

2)bad computer thats messing up the timing

3)carbon build up in the engine

bring those up and see what happens,

the spark plug is what you want to hear, its cheap to fix

the computer is alittle more of an inveinvestment

it sounds very much like a motor mount☺☼