i have a 2000 Ford Expedition with a 4.6 in it,i had ENGINE KNOCK AND WAS TOLD IT WAS A SPUN BEARING ON THE CRANK SHAFT,UPON ALITTLE MORE DIGGING I FOUND THAT THE RETAINER CLIP ON THE LIFTER HAD POPPED OFF AND BENT THE PUSH ROD AND THE ROCKER ARM.ALOT CHEAPER THAN A SPUN BEARING
Could be that your valves are out of adjustment or if you have the nonadjustable valves then it could be a build up of carbon on the valves.
And engine knock is normally caused but I worn crankshaft bearing or rod bearing.
If it's a engine knock it could be low on coolant or have head damage...
bad bain bering
Engine knock happens when an unbalanced air and fuel combination occurs inside of an engine cylinder. If the problem is not corrected the vehicle runs the risk of having a piston malfunction.
The lack of oil?!?
your knock sensor could need to be replaced
a lot of times its your timing belt, if its more of a knock its could be a rod knock
If the knock sensor failed the CEL (Check Engine Light) would be illuminated and the engine may "ping" or "spark knock" under load. Serious "spark knock" can damage the engine if allowed to continue.
Low octane fuel, timing to far advanced, overheating.
Could be too much timing, too much compression for the type of fuel being used, or maybe a vacuum leak creating a lean condition.
If the car is on and the knocking seems to be coming from around the engine, then the engine could be low on oil. You need to put oil in it immediately or run the risk of ruining your engine. You also could have a stuck valve or maybe your rod is knocking the rod will knock due to improper o ring around it which doesnt give you very good seal inside of a piston.