Coolant Question when Replacing Heater Core

SpeedRacerX

Well-Known Member
Joined
Jan 20, 2014
I know I'm going to get told to use the search button for this question but after all the research about how to replace my heater core and the really nice threads and writeups I found here and elsewhere, I'm still left with the following dumb question.

Do I need to drain the coolant first? When I disconnect the two hoses to the heater core, is fluid going to come pouring out?

The job itself looks like something I can easily, perhaps tediously, handle but since I've never done this before, I don't know if the coolant, it's fresh, should be drained first or not.

Thanks.

Sent from my SAMSUNG-SM-G900A using Tapatalk
 
That I've ever known no more coolant is going to come out then is in the lines themselves it won't come gushing out of the core draining it would not get the antifreeze out of there anyway drain pan underneath the area will be necessary though draining the whole system is not necessary unless you haven't done it in a while

Sent from my SAMSUNG-SM-G900A using Tapatalk
 
Last edited:
some will come put, but not much. That connection is the highest point in the system. Unless the car is upside down, most of the coolant is going to stay in place.
 
Just be careful when you move the old heater core. It will be full up to those tubes as well. If you're running antifreeze have the rest of the engine buttoned up tight as you do not want any antifreeze to get inside.
 
Take pictures of the metal brackets, washer fluid spritzers, and other parts before you remove them. There are also two screws down inside the plastic cover. Parts stores carry the wide weatherstrip that you will need against the firewall, and the thin stuff that goes around the rest of the cover. I also applied a bead of window caulk on the cover just above the wide weatherstrip, against the firewall. I think that's how the factory did it.
 
Some coolant will come out. I usually use rubber caps that you can get at your local automotive store and cap the ends of the heater core after I pull the lines off. Prevents any further mess during removal, and you don't have to be conscious of the way you pull it out when it is capped off.
 
Take pictures of the metal brackets, washer fluid spritzers, and other parts before you remove them. There are also two screws down inside the plastic cover. Parts stores carry the wide weatherstrip that you will need against the firewall, and the thin stuff that goes around the rest of the cover. I also applied a bead of window caulk on the cover just above the wide weatherstrip, against the firewall. I think that's how the factory did it.
Thanks. I actually bought a roll of glass setting butyl tape which should make applying the seal easy.

Sent from my SAMSUNG-SM-G900A using Tapatalk
 
Some coolant will come out. I usually use rubber caps that you can get at your local automotive store and cap the ends of the heater core after I pull the lines off. Prevents any further mess during removal, and you don't have to be conscious of the way you pull it out when it is capped off.
Good tip, thanks.

Sent from my SAMSUNG-SM-G900A using Tapatalk
 
Top