Here is a video i made of my ranger with the 4.0 OHV making noise, this happens right after an oil change. If anybody knows what causes this, or if they had this issue before, let me know, thanks.

 

Piston slap

98-00 have short piston skirts causing a rattling noise at idle. Ford deemed this normal.

Mine does it, its worse after a fresh oil change.

 

I know it sounds bad but like Blhde says, it could be normal. I live in Texas and although the manufacturer calls for 5W-30 oil, I use 10W-40 since I live in a hotter climate.

 

It is normal piston slap. I believe in 98-00 the pistons also had offset wrist pins. The only way to prevent it is to change the oil fast.

 

Just had the oil changed.

 

I know. What I mean is don't dilly dally while changing your oil. As soon as the oil draining out turns from a constant stream to drips, plug it back up and refill it. The longer you take the more oil drains from the skirts. The ford V10 had a similar problem and people found that using a thinner synthetic oil and prefilling the oil filter helped get oil to the pistons faster reducing the marbling.

 

I prefill every oil change on every vehicle. Doesn't seem to help slap but I don't get the dry lifter tick on a fresh oil change.

 

Mine makes a noise similar, goes away after the engine warms up. It's not the valve train.
The person I bought the truck from replaced the engine with a long block assembly from AutoZone.
2000 XLT, 4.0L

 

this is normal man, your engine will always make that noise. the 4.o ohv i have now makes the same sound, and its a 98.