Is it normal for blood to come out every time I blow my nose, even 18 months after Rhinoplasty?

Blood out of nose 1.5 years post op is not normal. See your surgeon to determine the cause.       

Nosebleed is not a normal condition, at any time. if you post operative bleeding and you've had a nose surgery, you must query a physician. there are different medical conditions to surgery that can cause bleeding and should be studied. I hope it has been helpful.Translation provided by doctor:Sangrado nasal no es una condicion normal, en ningun momento. si tienes sangrado post operatorio y has tenido una cirugia nasal debes consultar un otorino o el medico que te opero. existen condiciones medicas diferentes a la cirugia que pueden causar sangrado y deben estudiarse. espero haya sido de ayuda.

Bleeding from the nose even without a rhinoplasty is not normal and should be evaluatedDr Corbin

Persistent nasal bleeding is never normal whether or not an individual has had a rhinoplasty. See your surgeon or a nasal specialist.

No, this is not normal.  You should not have blood coming out of your nose.  See your Plastic Surgeon for a follow up exam to determine the cause.