Help! Heater Core

[woodpuppy]

I have a 1986 Coupe with AT. When I purchased the car a few months ago I did so knowing the heater core was not connected and bad. Well the time has come for me to replace the heater core (along with all of my other hoses).

Since the heater core was not connected I'm sure the previous owner "jury rigged" the system/engine so it would run "properly".

I am looking for the procedure for replacing the heater core and any diagrams that might show how all of the hoses related to the engine are routed and connections between fittings.

I'm going to take digital pictures and draw some pictures as well of what's there now, but since the heater core is not connected at this point I'm sure some of the connections will change .

Also if there are any words of wisdom, advice, tricks of the trade, special tools needed, or any gotchasad that anyone would like to share I'd love to hear from you.

I've already removed the radiator and cleaned out between it and the AC condenser awhile back, but if there are any other related task or maintenance items that should be done or are easier to do associated with replacing the heater core I'd appreciate it if someone would share that info as well. One that comes to mind is the thermostat, but there may be others.

So you know where I'll be and what I'll be doing on Saturday. I hope everyone had a good week and that you all have a great weekend!

 

[Toms007]

Well, I've heard that the first part they put in at the factory is the heater core and they build the rest of the car around it......

Apparently it's kind of....buried in the dash. However I have read that there is a "shortcut" to installing heater core in earlier models. I'll have to see if I can find that article. Good luck, I don't think it's one of those fun jobs.

 

[Toms007]

OK I found the "Fast Guy Method" of replacing the heater core....NOW REMEMBER... I HAVE NOT DONE THIS. I am only regurgitating what I have read in hopes that this will help you.

FASTGUY

Whoever wrote that huge "pull the dash out" article was a friggin' crackhead.

You don't pull the dash, instead, pull the passenger seat.

Pull the hush panel , drop the ECM and the door control module.
Remove the support bar going from the door pillar to the dash.
Use a 7mm to take the cover off the heater box.
Pull the cover, unbolt the core, re-install.

I removed the diagonal brace. There are 5 screws on the plastic cover for the core - 2 top, three bottom/sides. There are 3 screws retaining the core itself - 1 top middle & 2 bottom. As said, watch the position of the rod on the motor that opens/closes the door (if you have electronic controls). BTW, I also took out the pad in addition to the lower access panel - 4 nuts & much more room if you have full size American arms & hands. I got the upper screws restarted by placing a bit of tape on them & wedging them into my 7mm socket. It helps to have 1/4" drive flex adapters and every extension length they don't make Total time for me was about 5 hours for the heater core in-and-out. Plus a couple of hours to fix the broken dash frame and to eliminate the breadbox - not necessary, but seems to add a lot of "room" inside & looks way better One more thing - since you're there inspect all wires & the orange vacuum line. I found two damaged wires & a missing heat shield on the courtesy lamp. My new heat shield is two thicknesses of Bud can

 

[Toms007]

Here's another a little more detail here.

After removing the seat, I dropped the panel to expose the ECM. I dropped the ECM, but left the ECM brace where it was. There's a small vertical AC duct that meets up with the hush panel, I pulled that down. There's a horizontal AC duct that goes right in front of the heater core housing. I removed all the screws I could reach for that then just moved it out of the way. It wasn't necessary to remove it, which was fortunate because it kept going behind the center of the dash and I don't know where it ended.

Next there's a cable that comes through and mounts onto the heater core housing. Remove three screws and it comes lose, but it also attaches itself to a rod that goes into the heater core housing itself. It's attached by a white plastic piece that goes through the metal. I spent a few minutes trying to remove the plastic piece, but it turned out I just had to pull the rod right out.

After that's out of the way (in my case, dangling behind my head) you can access the big support rod bolts. There is one bolt per end, both 13 mm. On the top one I couldn't get an extension in there so I just used a 3/8ths and 13mm. It was torqued down pretty good so my knuckles took some abuse when it broke lose. The bottom bolt was uneventful, and the rod came out. At this point all I had left was the heater core housing itself.

There are a couple of exposed bolts that go into the firewall side of the heater core housing and bolt it to the firewall. I took as many of these out as I could, but found that it wasn't necessary and I had wasted time doing so. They were 10mm's, and all I really needed to remove were the 7mm's.

Remove all of them that you can see. There will only be two slightly difficult ones.. both at the top. One you can see if you bend your neck right, and one you can't see at all, period. I suggest you leave these for last. Take out the one you can slightly see first. Then pull apart the housing the best you can without breaking it (since it's still held together by one bolt at top). You can see where the tension is. Aim a socket with an extension and a 7mm at that spot and eventually you'll get it. It won't be fun, though.

At that point the housing will come apart and the heater core can come out. Installation was the reverse of removal, except one minor mistake I made.. the rod that comes out and attaches to the cable can pivot and become stuck behind the housing during installation. Make sure that rod is sticking out before you bolt everything back in.

I figure that since the housing doesn't have to be air tight (as evidenced by the big hole where the rod sticks out, and where the inlet and the outlet stick out), one could *probably* leave the invisible top bolt out. I personally didn't but it was tempting. I put it in last and there was absolutely no slack at top.

I used a 3/8ths, a 1/2, 7, 10, and 13mm's for each one, a deep socket for the seat, a blanket to lay on so the seat bolts didn't rip into me, and a good flashlight is vital. Mine had the head that I could point where I wanted. Make sure you put all your tools to where you'll always know where they are just by feeling around. It's alot easier than climbing in and out of the hole under the dash. A magnetic wand couldn't hurt either.

 

[mgord]

Thanks for the post

I followed all the previous post pretty closely. This job is quite a pain but doable. It took me 10 hours over a few days to complete. Including a couple of runs to Sears to get all possible extentions for my 1/4" drive socket.

My only recommendations would be to following the directions above and:
1) On the piece of wire sticking out which opens and closes the flag, I drilled a small hole in the end and looped a piece of wire through the loop and around the top to keep in in place while I put the cover back on. The little plastic piece broke while taking it out.

2) I removed the tire and part of the wheel well so I could move the hoses away from the nubs that come through the fire wall. This way I could bolt the core in place then wiggle the hoses back onto the nubs.

I was able to finish with no pieces left over and all bolts back in place. I highly recommend getting used to taping your bolts to the socket for easier threading with one hand.

Good luck to all....

 

[LVMYVT76]

I would add to test your new heater core before installing it and find out it also leaks.

 

[mgord]

Good point.

I installed the heater core and put the hoses back on. Before I did anything else I plugged the computer in and ran the engine for 15 minutes to make sure there were no leaks.

 

[AirJohn]

I replaced the heater core on my 85, used a shortcut instead of removing all the driver side parts. Before removing the heater box cover I carefully cut the air tube that goes from the left side of the heater box cover over to the driver side under dash air outlet. (The manual says to remove all those driver side parts to be able to get the left driver side air tube out). When I put it back together I used a high quality aluminum duct tape, not the old fabric type, to wrap the tube I had cut. The old style duct tape eventually deteriorates, the newer type lasts forever.

 

[joshwilson3]

I'd also make sure to get a good quality heater core. Probably AC Delco. And make sure the tubes are metal, which I believe all or most are these days. The one from the factory had plastic tubes. Which could crack if you had to replace a heater hose.