After listening to my engine a few times with the hood open and a friend driving, it seems as if it is knocking a little. It isn't a repetitious sound, and usually comes on when the engine is under load. For example, when I'm at a stop and put the car in first, if I let out the clutch really slowly without giving it any gas almost stalling the car, I hear a knocking coming from the block. Also, when in neutral, if I rev the engine to like 2000 RPM's, as the revs fall, I hear a knock/rattle in the block. Anyone have any idea what it could be? Fouled plugs?

 

my dads truck was doin the same exact thing. he just replaced the plugs and rotor in the distributor cap

 

sounds like your bearings might be shot! do not drive the car like that at all ,you will cause severe damage. $$$$!!!!

one way to tell is to drop your pan and look for metal shavings, the lazy way to do this is drop the oil onto a clean oil pan and look to see if you have any silver or copper colored shavings.

good luck

 

But if it were a bearing, wouldnt it make the knocking noise repetitiously at idle???

 

Rod bearings tapping on the crank shaft.

 

ok I changed my plugs and rotor, and it doesnt make the noise during free reving anymore. But it still rattles when I let the clutch out real slow without givning it any gas. Could it be something lose rattling under the car? CV or axle? I also recently had my tranny worked on(replaced diff and clutch). COuld the noise have anything to do with that?

 

I dont know what your setup is...but I had the same thing.

Turned out it was just my blowoff valve just hitting my strut bar and rattling a little.

 

How much does it usually cost to replace a rod bearing? Also, could it be the clutch or the flywheel making the noise?