Anyone replaced heater core lately?

[TC70C10]

Mine started leaking on the floormat on the K5 this morning.

Looks like all the bolts are up under the dash. Anyone replaced theirs lately and is it a pain in the asskk??

Tim

[bigblock73]

It isn't that hard to do on our trucks, it comes out from the inside. One thing, make sure you clean up the anti-freeze right away...it WILL cause your floor to rust if it sits there too long.

...Jeff

[PHOENIX]

I did mine a little while back.
I do not remember exactly what to do, but this list should help some.

I have a non-A/C truck and it was much easier then I expected.
A/C trucks may be different (vacuum hose instead of cables ? )

If you have not changed your coolant/water in awhile then begin by draining the system.
I usually unhook the lower radiator hose.

Get a small catch to put under the heater hoses on the firewall and disconnect them and let the coolant/water fall into your catch.
Go inside the cab (passenger side).
Remove the glove box door (screws across bottom of door).
Remove the cables from the heater box (cables go from the control panel to the heater box).
There is one cable for the heater and one cable for the defrost.
It is a good idea to label anything you remove so you know where it goes.
Now go back under the hood and remove the nuts on the firewall (3-4 ?)
If I remember correctly there are threaded bolts sticking out of the firewall with nuts on them (the head of the bolt is inside the cab and attached to the heater box).
So you only need to remove the nuts on the bolts (no other screws or bolts).
You should now be able to carefully remove the heater box from under the dash.
Once the heater box is out of the truck you can easily see the heater core.
Just replace the heater core and install (opposite of removal).

I would recommend replacing the bolts that hold the heater box to the firewall, they can get old and give you a hard time next time you replace the heater core. Also check the foam that seals the door(s) inside the heater box. Replacing the foam now is a good idea.

Good Luck!

[TC70C10]

Thanks Eddie,

I did the one on the 70 C-10 and I'm glad to hear it's not too bad on these model years.

I've got the aftermarket air, and I don't know whether to buy the w or w/o a/c heater core, so I'm going to remove the heater core before I buy the replacement so I can compare. Should save me at least one trip to the Autozone. I might even tie the upper and lower heater hose together and worry about the heater when it cools down this winter.

The 81 doesn't have vacuum lines for the air/heat/defrost so that should make it a little easier. I just got my dash all back together and I need a break from this restoration.

Found a leak on the low pressure side of the compressor which I tightened up last night. Going to refill with 134 and test it out tonite. Put a headliner in, that really helps keeping the cab cooler.

[Grim Reaper]

http://coloradok5.com/heatercore.shtml
Write up I did.

[TC70C10]

Thanks Eric.

That's why I like this site better than the Colorado K5 site. Members here seem to be more responsive. I joined that site, but I spend 98% of my time on this site.

I printed your article and will use it for reference. The inner fender well removal was a good idea. I knew there were going to be a couple of nuts that would be nearly impossible to get to. By cutting the inner fender loose, that should save a bunch of time and skin on the old knuckles.

Have a good one.

Tim