I have a 99 honda civic. The engine started knocking while my boyfriend was driving it. He said it had just started. It was low on oil so i figured it was just overheating. However that didnt fix the problem. I thought misfire but we just replaced all the plug wires and spark plugs. It is still knocking and the check engine light if flashing. A few mechanic friends that i called said my engine is about to blow. Just looking for other answers and to see if thats correct
It sounds to me like you mechanic friends are correct. From your description, the car was driven too long on low oil and is now suffering the effects. If you have topped the oil off and are still having the knocking sounds, it's more than likely the engine has damaged bearings with a classic rod knock to tell you about it. With a rod knock, it is only a matter of time before the engine self destructs.
Considering your car is a Honda, you should be able to find a decent used engine for a reasonable price. Honda made many Civics. Engines for these should be plentiful and relatively cheap. Maybe you can get one of your mechanic friends to install it for you for cheap. Better yet, trade your boyfriend in on one who has his man card and can do the work for you.
If it was low on oil and you have been driving it, then you have probably worn any number of bearings and possibly the cam shaft. The engine could be ready to die. Being low on oil is not generally a cause for overheating. Overheating would generally be caused by being low on coolant (water). If the knocking is a low pitched thud, then it could be coming from the crankshaft/con rod bearings. If it is a higher pitched tapping, then that would likely be the cam shaft. Rather than 'blow', it will probably just get noisier then stop.
there is another choice: You can locate the bad cylinder and then remove the valve spring, take out the piston rod, wrap a rag around it and hammer it gently on a steel or smooth concrete surface to straiten out the Push Rod a bit for re-use. Change the lifter also (chances are the lifter has pitted underneath). This procedure will smooth out the knock considerably but is not a permanent cure unless you use new parts.