98 dodge ram quadcab 1500 small 8 cylinder motor. when I start it there is a very loud clacking noise underneath. after it runs for a few minutes it becomes not so loud but doesn't go away. could it be a u-joint? or something else?

Pull valve cover off and look for any bad lifters. Or could be piston rod. Sounds like sticky lifter. Not good.

I suspect you have hydraulic lifters and the sludgy oil could plug up your lifters - as well as running that low on oil. Top off your oil and get an oil additive engine cleaner, warm your engine at idle only then change oil when warm. Add 1 quart of marvel mystery oil to the crankcase then top off with high mileage oil, like Valvoline. Run motor at idle only and see if this cures the problem - if not then you may need to remove the intake and replace your lifters, a costly and time consuming job. I would not try driving as you may waste the cylinder head or block by running a stuck lifter. There is also an oil additive specifically for stuck lifter and I think I would add that as well as the Marvel.
I hope the quick fix works for you and good luck!!!

P0300 Random/Multiple Cylinder Misfire Detected

P0304 Cylinder 4 Misfire Detected

If a cylinder is not firing it could make that noise. Check/replace your plug wires use dielectric grease in the boot connections. Could be a bad plug as well but I would guess a bad plug wire...

Number 1 is on the drivers side on the front. The cylinders are arranged 1-3-5-7 down the drivers side and 2-4-6-8 down the passengers side. The firing order is 1-8-4-3-6-5-7-2.

I have noticed that a lot of similarities between the 98-02 Dodge Ram line so this may or may not help. I have a 1999 Dodge Ram 1500 Quadcab and have taken pictures of the diagrams, you can check them out and see if they are the same...please post back and let me know so I can put that on the site anyways here is the link www.afreeland.com/index.php?page=DodgeRam

you could change the fan to an electric one and take off the old fan off why bother.....alternatively try soundproofing the bonnet/hood works for me(cheaper)

use a 1/16 drill bit to drill thru indicator to break bulb. light will not come on when started again

it's simply means that the lifter empties after a while so when you start it it fills up again and the you're good to go.

it's not very dangerous for the engine but in my opinion it's better to have it replaced...

Should have to remove a couple of screws, unbolt the door handle, then lift upward. It is held in by slots.

usually sits on passenger side on the inside of frame follow fuel lines from motor to tank ,its usually at the half way point between motor and tank inside frame rail