2000 WJ , noise coming from front diff, check oil and found there to be sand in the oil. I know I have a seal leaking but was holding off till the weather got better. I've been checking the oil level and its been good and without any grit in it. But we've had alot of snow, then high water from the melting snow. And water mixed with sand entered the diff. I can't change the seal right now, any good to get the oil out of the diff and replace it with good until I can change the seal?

 

There is a chance damage has been done if you have noise, but I would definitely change the fluid. While you are in there spray everything down with brake clean and get as much of the old oil and sand out as possible. It will ruin your front end in a hurry.
if it was mine I would buy the stuff to do it twice, refill it with a 1\2 quart of atf mixed in, drive it for an hour then clean it out and change the fluid again. The detergents in the atf will help pull out any grit you can't get to.
Why can't you do the seal yet?

 

I drained the diff and didn't find very much grit, just grey oil, so it's gotten wet. I used 3 cans of brake cleaner, drained and cleaned it out. Refilled with atf drove about 20,miles. Drained, cleaned and refilled with 75/140 plus additive. Drove about 75 miles, could barely hear anything from the front end. I can't do the repairs right now as the shop I use is booked the next few weeks. I'll keep listening and check it fluid level every couple of days.

 

Sounds like it might be ok. There are 2 areas to be concerned about with sand or grit in an axle. The bearings, which you can change without special tools, and the shims used to get the proper set up for your ring and pinion, wear the shims enough and your buying new gears. Doesn't sound like you have to worry about that.