new waterpump leaks when off

[camoit]

If you didn't put on a new O ring it's going to leek when cold or with out pressure. The pipe may have rust on it.

[t97]

Ok guys i went to the parts store and bought a generic pack of o rings and even used a bit of rtv around it and it still leaks just as bad as before. Do i need to order the o ring from mitsubishi or is my water pump just a little bigger? I bought the pump from advance auto and its from the brand "GMB". The rotor is a different style than the one i took off but im pretty sure that wasn't the original.

Also do you think if i wrapped some plumbers tape on the waterpipe it would hold?