Installed a new dish washier and after re-hooking up the supply,electrical, and drain line, After three attempts the washier will not flush up to the back wall and line up under the counter. I short about 3/4 inch.

After taking measurements of the washier depth of new and old washier there is about 1/4 inch deferents in the depth. No big deal ! Right! I did notice that , the drain line was utilizing old sink drainage line and was about center on the wall about 8" high off the floor and has a 1 1/4 cooper line with coming out of the 1 1/4 sewer pipe., which the washier drain line is hook up to the cooper line.

I reinstall everything back like the old washier , but not able push the washier back against the wall, to clear the deferents. I look at the back of each machine and noticed the old one had a 8" cleariness at the bottom and new washier only has 6 7/8 " clearenance.

Is reason, I am having trouble, is the wall/short cooper line is not clearing the new washier machine and is hitting the back of the unit and will not go back any further ?

Can a old sink drain used to support sink used as drain line on a cleariness.

It seem to me, regardless what I do, the old sink drain line on the wall , needs to be relocated and lowered. So clears the back of the new washier machine. I not really sure after I remove sheet rock, that I able to move the linke anywhere , without install a 90 % pipe and then I could create another problem with the low pressure drain line.

Help ! Tired washier dishes by hand ! Thanks RF

Cut and cap off the old drain to where you need it and then run the dishwasher drain line into the garbage disposal or into a wye branch tail piece.