Repairing cracks

HI,
I've just purchased a house and I've come across a little problem that someone might be able to help? There is a crack that runs along the kitchen floor from end to end the whole length. I've already removed the tiles and there is a cement base under and under that there is plywood sheets. the crack is in the cement. without removing the cement is there a way I can repair the crack so that it does not come back once I lay the new tiles over it? any ideas?

I really doubt that a fix exists under your terms and conditions. More than likely the crack is right over the juncture of the plywood sheeting. The only decent way to bridge the gap and have any bonding strength at all is with an epoxy modified mortar. Even if the gap was filled there is nothing to stop a crack from occuring on either side of the fix. The problem is movement, not the mortar bed.

I'm sure that 2000 is right. He's the expert at this. Here is a tip that might help, tho. A pro painter of 40 years experience, just told me about a trick that he developed to repair cracks on plaster walls/ceilings of old historical homes. He uses 8" strips of black plastic (PVC, I think) screen "wire" over cracks. He muds it in exactly as you would sheetrock tape. Says it works like a charm to prevent the cracks from recurring. Might help, if embedded in the epoxy modified mortar. Who knows. Can't hurt. Good Luck!