Is it bad to eat to much cucumbers?

No, well, not really. Short answer is no. But remembering you can even overdose on water, nearly anything can be done to an excess and cause some harm. Not specific to cucumbers, I have treated two patients eating excessive raw vegetables so that a bezoar formed (softball size and hardness made out of the white strands of an orange) lodged in the bowel and caused a serious obstruction.