Heater Core removal

[NCali]

1987 2 wd 1/2 ton with air
I have the heater housing out of my truck but how do I separate the plastic housing to get the core out? I have removed all of the screws I can find but the case will not come apart

[MIKE S]

You have to remove the one metal shaft that goes thru the top of the case. It’s not the one that the temp cable attaches to. It goes thru the top down thru a plastic diverter valve. It’s a press fit at the bottom of the valve. Be carful. Mine was brittle and broke. I had to epoxy it back together. Also the vacuum pod is also connected to the metal mode door and needs to be disconnected. You can reach thru the defroster side of the case after gently prying up and take out the connecting bolt or on top of the case there is a relief in the case right above the bolt that is made to be knocked out and you can gain access to the bolt. You can put a plastic or rubber plug back into the hole after you are finished.
 

[NCali]

Thank you , I will go try and remove it now.  what a pita

[ehjorten]

Never have I ever had to split the halves to get the heater core out! You simply remove the couple of screws that hold the sheetmetal piece on, and the heater core comes right out!

[MIKE S]

87 to 91 used a slightly different case. It does not have the metal back on the backside that goes up to the main case. It is plastic and it goes from the defroster vacuum pod all the way across the back side of the box and is part of the core carrier. The older ones also have a mode door vacuum pod with a hose on the outside and a hose on the inside of the case. 87-91 vacuum mode pod has both hose connections on the outside. Although the GM parts catalog is a little vague on year usage I haven't seen this type used on pre 1987 unless someone has swapped it out somewhere along the line.   

[NCali]

I just got my heater box back in. I have the plastic piece across the back that has to come out to change the core

After getting it mounted back in I have a 1/2 in gap between the defrost valve and the defrost duct
am I missing something? a sleeve
It was the same way before I took it apart but I sure lose a lot of defrost air

[MIKE S]

Normal. You could put some foam tape around it but I’ve seen one that fit any closer.

[NCali]

I read where someone else had the same problem and used aluminum tape . I had some and did the same
Thanks for the replys

[VileZambonie]

There should be no gaps or you will lose air flow. Something is out of position. If the seals are history, use mastic tape.

[MIKE S]

Mine is gapped and the tab for the duct to case faster lines up. So it may have had something like open cell foam or maybe something like camper tape in there. I don’t Remember seeing any that had it. Never gets colder than 28 degrees here with no snow so it hasn’t been a problem for me so I haven’t thought about closing it up.

[frotosride]

Yes there is supposed to be foam in there. I had to replace mine when I did my heater core 6years ago. If I had to do it again I would try and tape it because even the OE foam doesn't seal completely and defrost is much needed!

[Mike81K10]

Use foam to fill in gap with A/C Duct tape that is used on ducts in a house A/C system to prevent only leaks.

[VileZambonie]

That's what mastic tape is.