89 heater core replace - SmokinVette.com Forums
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post #1 of 6 (permalink) Old 11-29-2009, 12:42 PM Thread Starter
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Exclamation 89 heater core replace

Hey everyone, they built a corvette around my heater core. I need to see an exploded view of the box to be able to know where to feel for the bolts I can not see! T hanks for any help for downloads
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post #3 of 6 (permalink) Old 11-30-2009, 09:42 AM
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The fella knows his sh*t!!
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post #4 of 6 (permalink) Old 11-30-2009, 11:24 AM Thread Starter
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Smile Thanks!!!!

Wow! those articals helped a lot, and I still hope to find an exploded view of the heater box. At least I now know that this fix is possible, just need to save up for that swear jar! Thanks again.
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post #5 of 6 (permalink) Old 11-30-2009, 01:17 PM
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Give me a couple of hours ; will drag a HVAC unit out of the spare parts dept under the house and get some pics.

Last edited by vetteoz; 11-30-2009 at 01:24 PM.
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post #6 of 6 (permalink) Old 11-30-2009, 01:26 PM
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Have not done it myself but there is the "fast way" option where you remove the seat , lie on your back and access everything from underneath so you don't have to take out the dash

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. 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. 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.
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