Ug. Did it have that when you bought it?

Not sure how I would feel. I think I see evidence of encapsulation.

Here is a Liquidambar I have recovering from a deer attack.

Its new growth is more obvious to me. How does your whole tree look?

trees heal themselves.. ANYTHING you dream up would be contrary to nature... the process is called encapsulation ...

the tree may fail.. if it can not do it before the exposed heartwood starts rotting in a few years ..

if you have the budget.. just replace it..

otherwise.. its a great experiment to watch and learn.. as it copes with this..

could we see the whole tree.. and where the injury is.. your photo really doesnt give us the whole picture..

it might die above the wouldnt ... but if the root mass is otherwise wealthy.. the tree should resprout ...requiring so future pruning to get it back into shape.. and not become a shrub ... do you know if its a named variety????

i grew up on a suburban street that had all sycamores.. im not sure i would plant one in a small suburban yard... the huge leaves that fall all summer long.. those darn spiky seed balls... and sticks and branches raining down all year long ... and the possibility of anthacrose .. and the roots are not garden friendly.. 50 years from now.. lol.. tree time...

imo.. you could be do a lot better for what looks like a small back yard....

ken