1999 Ford Explorer coolant leak

That sounds like you are describing a freeze plug. It is a relief spot in the block in case of freezing that can pop out instead of cracking your block. Take a look at the picture below and see if your round indentation looks like this. A new freeze plug can be inserted and you will be good to go.

YES, that is exactly what it looks like. Thanks so much. Is it easy to replace and is it something I can do?

Well, I have no Idea of your abilities but it is not a real hard job. When you remove the old freeze plug the antifreeze (coolant) in the block will pour out so be ready for that. You can try removing the old one with a screwdriver and a hammer. Pound/tap the regular screwdriver out towards one of the outer (inside the recsessed part) edge of the plug until it either pokes through and you can pry it out of the hole OR it pops the plug out at an angle and you can then pry it out as well. Take the old plug to your auto parts store and get a correct replacement. They may have brass or steel. Also pick up some sealant like permatex to seal the outer edge of the new plug when you install it. You will need to clean the hole in the block to be free of debris, burrs, etc. To install the new plug you need to tap it into place until the outer lip is flush with the block. Use the largest socket that will fit inside the freeze plug and tap on the socket with a hammer. This will give even pressure as to not distort the plug on the way in. Put the sealant on the outside edge of the plug before you put it into place. This all make sense? Pay yourself when you get done with the job. :)

Yes, it all makes sense and I appreciate the help very much. I tried some radiator putty previously before I knew what it was, and that only lasted a few weeks. I will try it today and reply with how it went. One other thing, how much should I charge myself?

Yep, putty from the outside will get pushed back out as there is pressure in the cooling system as the engine heats up and the coolant expands.

As far as pay, if you are doing it as a favor, a nice steak lunch will do. If you find yourself cussing anytime throughout the job then the pay goes up.

When you are done don't forget to top the antifreeze back off. Dry the freeze plug area real good so you can look for any leaking. Let the engine run long enough to get all the way up to full temp to pressurize the water jacket. The tightness of the freeze plug fit is what holds it in, not the sealant. The sealant is only for any slight irregularities in the block surface to make a good seal.

Sounds like you'll do just fine. I like mine medium rare.

Steak it is. I am going to get a new plug in a few hours and will post the results tomorrow.

Thanks again.

Well I removed the old plug successfully, got the new one in place but could not get it seated far enough in the hole. The angle at which the plug is located made it impossible to use a socket to hammer it in with. I got it in as far as I could but still had a small leak. SO I resorted to getting an expandable one until I can come up with a way to hammer the steel one in properly.

Tight seal? No leaks with engine running and up to temp?

Enjoy that steak.

I got it seated but it would not go in all the way. It was dry when I put it in but when I started to tighten it, it started to spin. I went ahead and put the antifreeze in it and it does not leak, as of yet. I feel like it will hold for a while but will try to tighten it again tomorrow once it heats up a few times. Now the temp gauge is not working, dont know what I did.