Injecting epoxy under tiles?
 

I found a few small hollow pockets under some old tile. I'm adding new tile that will butt up to them to complete the floor. I was thinking of putting Devcon 2-ton epoxy into a syringe and injecting it into the mortar gaps that should lead to those empty pockets. My goal is to adhere it and put something solid under those spots. Anyone every try this? I hate to have those tiles break later due to being unsupported. Thanks.

Uni Bond Tile repair Glue
 

See if you can find this product at a local tile supply around your area, this is a great product and I had good experience with it for long time now

Uni Bond Tile repair Glue

Good luck

Good sounding stuff. FYI, I tried the epoxy but couldn't get it to flow thru the needle even though it was a larger one. I just proceeded with laying the new tile around it. I will consider Uni to correct it.

Uni Bond is a great product...I think we used that over Epoxy as well