I have a 87 mustang that i am replacing the heater core on. I have the whole dash apart. But does anyone know how the heater assembly comes off the fire wall so i can get the cap off for the heater core?
If you are talking about the plastic box that holds the heater core and the evaporator core. There are two studs on it that go through the firewall. You have to remove the nuts off of them from under the hood.
If you're positive you have all the bolts/nuts out, spray a little powerlube or wd40 on the rubber firewall grommet, and lightly tap the 2 firewall bolts and old core ends with a hammer. you will be surprised how tight that little rubber peice will hold that core in there.
there are 2 studs that go through the fore wall and there are two bolts that hold the assembly on the inside.....did you pull your whole dash out? it makes it easier to get to everything. those 4 small bolts that hold the heater core cover on are a pain in the a$$ too if the dash isnt taken out completely