Thank you for contacting Ask Extension. It appears that there are a few things going on with your tree. Maples unfortunately are somewhat prone to this kind of bark-splitting. The good news is that they often are able to heal the wounds and recover. There are many causal factors that can contribute to this happening. The actual split probably occurred in an event know as frost-crack. This happens when thin-barked trees are exposed to sudden changes in temperature. For example, during the winter when the sun strikes them in the morning. The problem can be more likely when trees are fertilized during the growing season because this leads to vigorous growth and thinner bark. Try to avoid making summer lawn applications of fertilizer that are within the reach of the trees roots (the drip line).
To hasten this tree's recovery I would recommend minimizing the amount of moisture that reaches the wounded portions of the trunk. You can carefully cut away the loose bark, but try not to damage any of the wound healing callous tissue. Removing the loose bark will keep moisture and pests from gathering underneath. If you have a watering system you can adjust the sprinkler system so that it does not strike the trunk of the tree. During the winter months, you can wrap the trunk with a tree wrap that you can purchase at garden centers. Wrap it when all of the leaves have dropped, and make sure to take the wrap off around March to mid April. This will help that the sun does not warm the area more and cause more cracks. You can pull the mulch back to about 3-4 inches from the trunk to help eliminate extra moisture to the cracked area.

You will probably see some early fall color in portions of the canopy supplied by the vascular cambium on that side of the tree this year. However, with some TLC this tree will hopefully provide you with many more years of service. If you want to contact an arborist to see if anything else can be done, go to http://www.treesaregood.com to find one in your area. 

No, we do not recommend sealing the 'wound'. It is because if it is not dried out, or insects are there, you are sealing it in. So leave it open and just cover it during the winter months.