I got a 2003 Dodge Ram 2500 5.7 Hemi given to me. When I fire it up there is a nasty sounding knock going on. Check gauges oil pressure goes up and down. When I hit the throttle a little it seems to go away. But the oil pressure goes down up constantly and the knock is still there. I’m trying to figure out what direction to go before tearing into it. Trying to get some input from people that have had the same issue. Could it be rod bearings, main bearings, valve issues, bad motor all together?? Engine has 293,000 miles. Was told it has been rebuilt but I don’t have any proof of that being done. Still a great looking truck and would love to figure it out and get it going again. I have drained the oil and it didn’t seem to be metallic looking. Oil pickup tube was clear and nothing clogging it. How would I check and inspect for bad rod bearings? Any help would be greatly appreciated in what direction I should go.

 

If it was given to you, it may actually be worth throwing another (used) motor at it, and call it a day. Especially if the rest of the truck is in decent shape.

I would put a mechanical oil pressure gauge on it.... You can get a cheap one from the local auto parts store for less than 30 bucks.... that will tell you exactly what your oil pressure is doing.... which may be enlightening....

 

That'd be the way to go. A used motor in good shape shouldn't cost too much.