My van is making noise like knocking inside the engine & it's getting louder when i'm driving.

Piston noise makes a noise that goes away when the engine warms most times, rod knocks get much louder as the engine is loaded, Keep driving it and see what blows? Have you checked the oil pressure with a mechanical gage?

time to pull the sump and check for a main bearing slipper rotating in the block
the knock can also be a big end
what ever it is any knock that gets louder when it revs needs urgent ionvestigation

Sounds like a rod bearing knock.

Sounds like a tapping maybe lifter. Maybe valve check under valve cover.

sounds like you broke a connecting rod...drain your oil look for metal..

sounds like you have a engine problem and if you lost the water coolant where did it good and where did it leak from. you may have a leak sparying coolant on the alternator which is not good and may destroy that also. if you got the engine so hot you ruined the bearings you will need an engine over haul or replace the engine. not sure how old the car is so cost may be more then the thing is worth. no point spending 2500 on a 500 dollar car if you get my meaning. check the oil and make sure the coolant didn't going to engine. that is also bad. need to find the leak or leaks and solve a couple problems. you can drive with it knocking but its just a sign its going to need to be fixed sooner then later and may stop running at any point.

jack up each wheel and turn them see if noise is comeing from wheel moveing or could be in drive train or worn out brakes squelers going off

Hello
Has the engine been run low on oil? Does the knocking get louder as the engine warms up? Have you had a automotive technician listen to this noise? Pistons don't really knock, the bearings in the engine called the crankshaft and piston connecting rod bearings do make a loud knocking noise, if that is the case the engine must be removed from the car and rebuilt.

1995 Ford Windstar 3.8L Engine Knocking noise on top side of engine near center of Air Plenum. Engine was completely rebuilt 2 years ago (28,000 miles on Re-Built Engine/ 156,000mile on Van). Coolant level is SAT, Engine oil level is Sat. Van was driven 2800 miles since last oil/filter change. Engine started surging as van slowed down to make a stop then engine shut off. Restarted engine and heard knocking noise. Shut engine off immediately. The oil light flickers on dash with engine running. Do fuel injectors make tapping noises when degraded? Is it possible hydraulic lifter not able to leak down or does not fill with oil? Oil pressure issue with the dash light flickering? I can see if the engine has allot of miles on it, the intake and exhaust valves begin to leak-by how ever this not the issue. Where do you start to locate engine knock noise? How is oil pressure checked to see if pressure is too low? Any help where to start would be appreciated.

It's a common problem with these cars i am actually fixing mine as of now. That car is all about oil pressure and when it is low you'll start to get a tap and or what sounds like a knock due to the lifters not having enough pressure. Try taking your oil pan off and check your oil pick up line going from the oil pan to the turbo. A lot of times it gets a lot of sludge build up and makes the pressure little to none. If that looks clear check the slump inside the oil pan and see if that has sludge build up. Well hope this helped