Engine making "diesel noise" loose rocker arm ?

Hi, i have a 2001 Dodge Ram 1500 pick-up with the 3.9 liter v6. recently i had a loud knocking noise coming from the engine, the oil pressure is low and so are the oil level. actually just bought the truck and i don't think the previous owner had even change the oil because it is very very dark. i went ahead to drop the oil pan, there's no metal shaving, but i found what seems like sludge and small chunk of sand like material. i check each rod and non of them move up and down, but they do move side to side and some make a slight tapping noise when i wiggle them. anyway i took the rod bearings off and found that some of the bearings have a copper spot on them, which is probably due to oil starvation, so i bought a new set and put them in. then i start the truck and got another surprise, the knocking noise that i was talking about is gone, but now my truck sound like a diesel engine. if you know what i mean, it's not a knocking or tapping noise anymore, now it just sound exactly like a diesel engine. i don't know what is the problem, could it be the main bearing ? i forgot to mention i did pull out the main bearings and both of them are scourged, it has a small scratch line, the other bearing have some small scratch near the top of the bearing. there's no way i can change them out unless i pull out the crankshaft right ? i tried %26quot;rolling%26quot; them out but was not successful, so i just replace the bottom half of the main bearings. i also took apart the timing set, the timing chain looks good and so are the gears. although they are very dirty, filled with carbon deposit. the next thing i did was to remove the valve cover and check on the rockers and springs. i have one question about the rocker arm though, with the engine on TDC, no pressure on the valve, i'm able to wiggle the rocker arm side to side to a point where i can make a knocking sound, how much play should they have, I've checked on the manual and i have a non adjustable valve so i don't know if this is normal. they don't look normal to me because they move quite a bit, i know there should be clearance but not that much. i also took a look at the push rod and they are filled with carbon on the side, they don't look bent, will these push rod go bad ? maybe they are worn out ? i don't know. any help would be very helpful, i need the truck for work so i need to get it fix as soon as possible, thank you.Engine making %26quot;diesel noise%26quot; loose rocker arm ?
Put one can of Lucas engine oil treatment in the oil may help a lot.Noise may come from oil pump sucking air after the bearing job,causing starvation of oil in the valve lifters.Should have replaced the oil pump when doing all that.Engine making %26quot;diesel noise%26quot; loose rocker arm ?
How about adding some oil if it's low? That's your noise. Problem now is, there's probably some damage. Plus, God only knows what you've screwed up by trying to fix it.Engine making %26quot;diesel noise%26quot; loose rocker arm ?
Sounds like lack of oil changes and pickup screen was plugged with crud and caused damage to crank and bearings. It will probably need a crank replacement or grinding.Engine making %26quot;diesel noise%26quot; loose rocker arm ?
U Just replace the bottom half of the main bearings. U can't do that as the crank will ride only on the bottom of the bearing.They are matches bearings and have to be installed as a pair. Big mistake. Best take it apart and do it correct or U will damage the crank.They come out only 1 way with the lock notch first.and then install the new 1 the same way.Engine making %26quot;diesel noise%26quot; loose rocker arm ?
the 3.9 is an old design taken directly from the 318, its actually identical with the exception of 2 missing cylinders. my guess is you need to adjust the rocker arms, if i recall, its 1/2 turn past snug. you should be able to adjust them with the engine running, just leave the valve covers off and adjust each one slowly until you find the one tapping.