Yes, you do not have to remove the engine.
Can the oil pump be replaced on 1994 Ford Ranger 4.0 without pulling motor?
Sometimes it's possible to change the big end bearings by pulling the sump off. But to get to the small end you need to get the pistons out. And if you're pulling the sump, and the head(s) you might as well get the motor out first as it'll probably be faster.
No. Crank and main bearings can be get at by dropping the oil pan, but to get to the small end rod bearings you've got to get the pistons out.
Bearings on Inifinitis should be replaced after every 30,000 km. If not, they can start grinding with or without noise. If you drive in this fashion for a while, you risk losing a wheel.
I assume you mean to ask how difficult it is to change the main bearings WITHOUT pulling the engine out of the vehicle. Don't bother. To properly replace the main bearings you need to pull the crankshaft away from the engine far enough to be able to put a micrometer on the bearing surfaces of the crankshaft. To do that you need to disconnect the crankshaft from the transmission AND pull the pistons part way out. Also, depending on the type of seal used, many rear main seals must be replaced by pressing them into place after the crankshaft is in. Don't even try to replace bearings without first verifying the status of the crankshaft. It must be round and within tolerance. If the old bearings have worn there isn't much chance that the crankshaft hasn't been affected.
when installing them always pack the bearings with grease, if the bearing has been run without grease and making a roaring sound it is probably bad and needs replaced
Yes. You should also replace the race at the same time.
I don't believe you can because the oil pan on vans are double sump pans and there wouldn't be anyway to get the pan out of the way because of the crossmember.
Just remove pan and change bearings.
By "siezed", I'm guessing that the crank bearings froze. If that's the case, either a complete rebuild (no sense pulling it out and fixing the bottom-end without doing the top end also) or a new or remanufactured engine
Yes..you should be able to. You'll have to take off the starter, remove the front engine mount to be able to lift the engine slightly then remove the oil pan.
Remove the trans pan and then the filter. If the pan is on the front of the transmission, it cannot be replaced without rebuilding the transmission; because the bearings must be removed in order to get to the filter. Ford Contour transmissions do not have removeable filters. There is a metal screen which generally never needs to be replaced.