heater core question

[Big GMC truck]

1984 gmc k1500 305
I needed to replace my heater core. So I took out my glovebox and discovered this black box. I'm assuming the heater core resides in the big black box. My question is how do I unbolt the box from the firewall. Inside the cab, I see these circular bolt looking fasteners that hold the box to the firewall. How do I unscrew them? Thanks

 

[Skigirl]

IIRC the front of the heater distribution box (the big black box that covers the heater core) has round headed bolts in front with hollow nuts in the engine bay side. Unbolt it from the bay. I removed the inner fender to get at them easily IIRC - been a long time since I changed out the heater core.

I took pics as I removed stuff, so I wouldn't mess it up[ gettting it all back together.

 

[Big GMC truck]

To get to the nuts, do I have to take the blower motor assembly off?

 

[4xcrazy]

As mentioned, you may have to remove the wheel well / inner fender piece to get to one of the nuts, it's tucked down in a hard to reach area,,,


that just didn't sound right.

 

[R77K10]

no you dont have to

jut start taking screws out inside the cab youll figure it out, its not that bad

 

[Skigirl]

Like R77 said, no you don't need to remove the blower motor. You will need to unhook the vac line stuff and I think there's a connector of some sort to one of the doors inside the housing, on top of the distribution box. I took pics along the way so I wouldn't forget where everything went and its position when I removed it.

You get some spillage when you remove the core. Make sure any carpeting is moved out of the way and you have some towels or something there to sop stuff up.

 

[4xcrazy]

no you dont have to

jut start taking screws out inside the cab youll figure it out, its not that bad

i didn't say anything about the blower motor assembly, i said you had to remove the inner fender well to get to one or two nuts that are located to far down in a cramped space to get a wrench or anything in there,,,remove them from the inside???? they are flat round surfaces, nothing to grab on to????
then you can remove the heater box and flapper unit thingy, being careful of the vacuum hoses and little plastic clip that connects to the flap door.

 

[K5er4Life]

As mentioned you have to pull the inner fender only so you can get to one single nut that holding on the air box thats under the dash. The rest of the nuts are easy to get to, its only that one thats buried in between the firewall and fender. Once you get the box out the rest is easy as far as putting the new core in. This might help a little bit...http://coloradok5.com/heatercore.shtml