Rear wheel bearing (1999) very loud, how do i fix
Before changing the real wheel bearings, you should thoroughly inspect your rear brakes. You would disassemble the back brakes anyway to change the bearings, and changing the brakes is easier. Remember to block the wheels up front, yes - safety first. As you pull off the rear drums, if you have to struggle to get them off, then that is a definite sign of wear and you'll need to do a rear brake job. As rear drum brakes are used, they have an auto adjust screw that tests and resets your brakes to ensure they are at proper distance to the drum surface. As brake shoes wear into the drums, they can create a groove or lip on the inside of the drum that the brakes will get caught upon when you try to remove worn brake drums. There should be a little hole on the interior side of the brake drum assembly and where you can fit a brake adjustment tool into. After you get the tool in there, it will touch against a star shaped wheel which is actually an adjusting nut. If you have a very small phillips screwdriver, place it inside this same hole and push the little arm that is touching this little star shaped nut. Everytime you back up and hit the brakes, this automatic adjustment lever pushes down on the little star shaped nut making sure that the brakes are not loose (keeps them snug). After you have this lever pushed away from the star shaped nut, use the brake tool to begin turning the star shaped nut until you have moved the screw back together, and the brake shoes have moved back towards each other, and you should then be able to easilly slide the brake drum off.
Once you get the rear drums off, you should try to turn the rear hub on each side and listen for noise and the feel of metal grinding (it should turn freely and smoothly). If the brake pads and drums are in good shape (plenty of brake padding left and no signs of metal wear upon the drums) AND you can feel and or hear the grinding as you turn the wheel hub assembly, then proceed with continuing to replace the rear wheel bearings. However, the more likely scenario is that you need a rear brake job, and doing a brake job is still easier than continuing to tear your brakes apart to replace the hub bearings.
You can check out a copy of Chilton's Auto Repair Manual Hyundai Excel 1986 - 1993 from your local public library. You can also buy this manual on the internet by using your favorite search engine (yahoo, google, etc) to locate a book seller.