I drove my car home one day and I didnt notice it until I pulled into the garage I heard a knocking noise. I got out inspected and it was comming from the lower front end of the engine near the crankshaft. I also notice it looks like my crankshaft pulley was off balance an wobbling a small amount. I put my car up on stands and check the torque converter flexplate and flywheel for cracks or being loose and everything turned out kosher. The knock is not all that loud and even stops periodically and starts back up and when under the car the noise seems to be comming from the crankshaft. The harmonic balancer is not loose nor the crankshaft pulley. I had plenty of oil during the time is started and I dont recall running it hard. Can anyone give me any if or suggestions. I have a 5.7. Thanks in advanced.

 

The intermittent knock like that is usually rod knock. As the bearings wear, the rod will start to slap around on the journal, which is the knocking you hear.

You might want to drop the pan and check the bearing clearances. If the tolerances are loose, but the journals are still nice and smooth, and not out of round you might be able to get away with an oversized rod bearing to get alot more life out of the engine. Although I've seen cars that survive another 100,000 miles once the knock develops.

Good luck

 

I would hope so I bought this car when it had 34,000 miles on it 3 1/2 years ago and it seems if I have replaced almost everything in that engine. It only has 87,000 miles on it now is that usualy for a rod knock?