2000 dakota 4.7L. When first started after sitting sounds like no oil in top motor. Sounds like valves chattering. Only last for about a second. Then starts up fine as long as it doesn't sit for awhile. Also inside filler tube is milky oil (water). Check dipstick and oil is fine. Is only in filler tube. Clean filler tube and drive, milky oils starts building up again.

This type of noise is usually caused by malfunctioning valve lifters or an exhaust manifold leak. If the noise lasts for more than a minute and completely disappears or dimishes after the engine is warm, the most likely cause is an exhaust manifold leak. If the noise only lasts for a few seconds, the most likely cause is a valve lifter malfunction. You should start your diagnosis with a visual inspection of the exhaust system. Inspect the exhaust manifolds for leaking gaskets or cracks. Black soot marks where the manifold mates to the cylinder head are key indicators of an exhaust manifold gasket leak. Inspect for broken exhaust manifold bolts. Inspect the gasket area where the manifold bolts to the exhaust pipe. Small exhaust leaks can often self seal once the metal engine parts are heated and expanded.
If there are no signs of an exhaust leak and the noise dissipates a few seconds after starting the vehicle, you should suspect an oil control or valve lifter malfunction. Hydraulic valve lifters use the engines oil pressure to expand the lifter which provides a zero valve lash clearance. This prevents the valves from tapping. When the engine is shut off, a valve and spring in the lifter keep it expanded and retain the oil within the lifter. If the valve or spring allows the oil to drain from the lifter, it will collapse. Upon start up, the lifter will take a few moments to "pump up" and expand as the oil pressure builds in the engine. During this time, the valves may tap since there is clearance between the rocker arm and lifter..

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change the oil filter to a better quality wit an anti-drain back valve , change oil and up grade to 30w-50 oil viscosity
remove and check the leak back rate for the hydraulic followers
the problem is that the oil drains back from the valve train resulting in a noise until oil pressure is restored

Valve chatter sounds pretty serious. Replacing coil pack won't help. I would check compression, if low, squirt a little oil in the plug holes, and if compression doesn't come up, bad valves.
You might need to check/set valve timing again, too.

Well, first off would be to replace the faulty sending unit so that the oil pressure will stabilize. Second, if I'm reading this correctly that you have no oil in the oil filter at all? If not, your oil pump could be quitting or it did quit. It's recommended not to start the truck until it can be checked for oil pump operation. Have the valves been chattering badly? The only 3 things that would prevent oil from getting to the oil filter are a blocked passage, a failed oil pump or no oil in the motor at all. When the oil guage has that fluctuation is when the pump is going out or again the engine has no oil or a leak so massive that the guage can't hold a stable reading. Good luck

Sounds like the lifters are tapping until the oil pump get oil up to them. Could be oil leaking out the top of the motor or your lifters may need adjusted.

No guarantees, but it may just be that oil is draining back into the pan when the car sits. Once you fire it up, it knocks till the oil is pumping again. Especially if it only does it after the car has been sitting for hours and hours. Good Luck!

It sounds like the hydraulic lifters are bleeding down after sitting for a while... there are ball checks which are supposed to prevent this... Try using a good engine flush (a product that frees sticky lifters) and replace the oil with a good synthetic... Hope this helps...;-)

How many miles? Sounds like its time for a motor rebuild. I would do a leakdown test, puts the cylinders under pressure and it is supposed to hold it for a certain amount of time. Or if you do not have access to a leak down tester, a compression tester. Sounds like the motor has quite a few miles. If you want to limp it to its death, put some thicker oil in it. 20w50.

these 3.3l engines are equipped with timing chains. if vehicle has prolonged down time, typically more than 4 hours, vehicle makes a chatter until the timing chain tensioners put tension on the chain. you will need them replaced.

sounds like a cv joint