86 Suburban heater core

I'm getting the dreaded coolant smell in the cab with steam coming out the defroster vents. Looks like its time for a new heater core (especially with the cooler weather that has recently arrived). Anyone changed one of these? Are there any special things to watch out for?

Amazingly enough, I just changed the front one on my 89 suburban yesterday.
Not too bad, took about 4 hours.
The trick is to take off the passenger side inner fender well, it makes life a lot easier. You can see what you're doing and move the core around a lot easier.
I have done 2 others before without taking it off and it was an all day job.
Taking off the dash cap helps and is easy to do.

If you have any questions don't be afraid to ask

Thanks for the pointers, I'll definitely pull the inner fender. This looks like a project for the coming weekend. From looking at it I assume the heater case separates at the firewall so I'll just need to pull the inside box, correct? I've not pulled the dash pad before is there a trick to it? Attachment points? A casual look at the project looks like pulling the glovebox will give additional access. Anything else in the way?

Yep, it splits at the firewall. Look for the captive bolts, they will have nuts on the engine side and probably be covered with sealant. Try to get the sealant off as much as you can before taking off the nuts.
Wire brush works pretty good for this.
The dashcap should have some 1/4" screws holding it at the bottom edge, also remove the top 4 screws on the instrument cluster.
The dashcap has clips that hold it down in front, be careful not to break them when you pull the cap up and back.
You will definitely want to pull the glove box, it has 4 screws on the bottom hinge and comes right out.
There might be some differences, considering mine is an 89 but you should be able to get to all the hidden screws.
That should be it for getting it out.
Remember to just remove the brackets for the cables, but leave the cables connected to the brackets and remeber where the vacuum lines go.
Splitting the case once you have it out isn't hard , it's just kinda tricky. You might feel the urge to just start sawing on it. DON'T! It will come apart.
Take you time and you should be fine.
Good luck!

Whats the advantage of pulling the dashcap? Mine is badly cracked and in such poor shape I'm afraid that if I take it off I'll wind up with way more pieces than what I started with. Since I don't have a replacement I'm reluctant to push my luck with it unless I really need to.

It just makes it easier to get to and see. Not totally necessary, but helpful.

Ok I'll take a shot at it without removing the dash cap first, if it gets to be too much of a pain then I'll take the plunge. Thanks for the tips! Current plan is to tackle this over the coming weekend.

I did mine in my 87 without pulling anything from the top... dash cap wise.
It took me about 3 hours and all I remember taking off was the glovebox... I think!

Well I pulled the heater housing and in the process of taking it apart to get to the heater core I broke off the ear on one of the air director plates. Anyone have any good luck with a particular glue/adhesive repairing this black plastic?

I used Gorilla Glue, but you have to clamp it for a couple of hours. It expands as it dries.

Whats the advantage of pulling the dashcap? Mine is badly cracked and in such poor shape I'm afraid that if I take it off I'll wind up with way more pieces than what I started with. Since I don't have a replacement I'm reluctant to push my luck with it unless I really need to.

That sounds like an excellent excuse to visit your local upholstery shop (or even a fabric store) and get a marine-grade vinyl in a nearly matching color, and re-wrap the upper dash pad. You might also find one in a salvage yard, but the chances of getting one that old is slim, and getting one in better condition is even less likely.

Heater core replaced, heater reinstalled all seems well but with the minor exception that I don't have air flow to the defroster so I must have mixed up one control line or another. Will have to revist. I ended up using JB weld to glue the air director flap (so far so good). The advice to pull the inner fender was a lifesaver! Dashcap will need to be a later project but I like the idea of rewraping it with marine vinyl.

Heater all done. Traced the lack of defrost back to having incorrectly hooked up the vacuum actuator lines. For future reference: Make note of which line goes to which port, it is important (and you have 3 chances to get it wrong)! Also I would suggest hooking up at least the back vacuum line on the actuator with two ports while the heater case is still loose; once you get the case up into position it is a b!@#$ to get the line on as there is very minimal clearance between it and the firewall. Made some adjustements to the control linkage for the air deflector flaps and lubed their contact surfaces with silicone spray and now have better heat and defrost than I've ever had in the 5 years I've owned the truck.