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My heater core finally crapped out on me. Didn't pour water on the carpet but was shooting steam out the defroster vents when I turned the heat on, so that's not good haha! I bypassed it for now by looping the hose with a 5/8" to 3/4" fitting, but would like to replace it soon.

I've never done one before, so I have no clue what to expect. Looks like there are 5 or 6 bolts or nuts holding the case in to the firewall case, and then somehow it's clipped into the case? I found some pics online but no good videos or anything.

Can you change it without taking apart the dash or removing the inner fenderwell? Not sure how difficult of a job it would be, just wanted to get some input so I know what to expect.

Thanks!
 

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i was going to tell how i did my 66 years ago but then i see your talking a 72. so i'm in the dark like you. but one tip to make it easier, remove the pass. side bucket to make it so much easier on the back. an i did have to remove the glove box liner to get to some of the hardware.
 

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Mike - 74 Nova Baltimore, MD
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Did your 72 Nova have factory AC?... or originally a Non-AC car?

EDIT: Disregard question above. I looked at your garage and see you have a non-AC Nova.
 

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Mike - 74 Nova Baltimore, MD
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I replaced the heater core in my 74 Nova several years ago.
You do not need to remove the outer heater core cover that is attached to the engine side of the fire wall to replace the heater core... but you do need to remove the 5 speed nuts (2 top side of heater core cover and 3 bottom side of heater core cover) that are attached to the bolts that come thru the firewall cover. These bolts hold the inner heater core box to the car's interior firewall. The speed nut that is located on the bottom side of the cover (behind the inner wheel well) is a little difficult to get to... but you do not need to remove the wheel well or the fender.

Once the speed nuts are removed, you will need to remove the glove box to gain better access to the inner heater core box. The glove box can be removed by unscrewing the inner screws that hold the glove box in place. You may also want to remove the passenger side seat to help with the removal process, as it can get a little awkward laying upside down on the front seat while trying to work under the dash... but this step is not necessary. I also advise putting some old towels under the inner heater core box to catch any coolant that may leak out of the heater core during removal.

You will then need to un-attach the 3 cables that are attached to the heater core box that is inside the car. Some of these cables can be tricky to get to. IIRC, I had to loosen the inner heater box from the firewall and maneuver the box to get to the cable attachment points. Be sure to also disconnect the wire going to the rheostat switch (fan speed controller) on the inner heater box.

Remove the heater core box from the car. The heater core is in the heater core box and is held in place by two retaining clips. Remove the retaining clips and remove the old heater core. Install new heater core into heater box and reinstall both retaining clips. Reverse the heater box removal instructions for installation.... BUT be very careful while inserting the heater core tubes thru the holes in the firewall. It is easy to bend these tubes and cause a leak where the tubes are soldered to the heater core.

NOTE: If you are going to replace the heater core in your Nova, you might want to consider converting it to a big block heater core (this is what I did - Arrow).


I think it looks a lot cleaner in the engine bay... and also prevents hitting the heater core tubes (that can lead to future leaks) as you are working on the engine. If interested in this conversion, let me know and I can post some additional steps (with photos) that would be required.
 

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If you need a heater core I have the original that came from my '71. I converted mine to the big block config too. It's been in dry storage for 20+years, and as far as I know is still good. I'm in Clarkston.
 

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RifRaf (I wish you guys would put your real name in your signature) has it right for your 72. Speed nuts off on the firewall side and drop the heater box inside the car. Removing the glove box and front seat are a must to get at things easily.
Just one thing, if you want to change your heater core to the big block configuration you will have to change the cover on the firewall. That can involve removing the inner fender to get at the bolts around the fan housing. The big block configuration is so much tidier and should have been used on everything in my opinion.
 

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You can get to it on either side. I prefer under the hood as you will end up doing a lot of cursing when working up under the dash. If you pull the cover off under the hood you can expose it. Yeah it is over simplified because my fender is off but it still isn't that bad. Remove the clip on the left then you can work it out. When replacing it make sure the heater core slides under the clips on the right. The clip is designed to slide the core in and out.
 

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Mike - 74 Nova Baltimore, MD
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Just one thing, if you want to change your heater core to the big block configuration you will have to change the cover on the firewall. That can involve removing the inner fender to get at the bolts around the fan housing.
Mike, I was able to use the original/existing small block heater core cover (located on the firewall) when I installed the big block heater core. I left the small block heater core cover attached to the firewall and used a hole saw to drill a couple holes into the cover (no need to remove the fender or inner wheel well). If using the original small block cover to convert to a big block heater core, you will need a "Big Block Heater Core Cover Plate and Gasket" (See links below).
Cover Plate
https://www.ss396.com/nova/AL-305.html
Cover Plate Gasket
https://www.ss396.com/nova/AL-963.html

For those interested, below are the steps (with photos) I used to convert my existing small block firewall heater core cover to a big block cover.

After you remove the heater core and heater core box from inside the car, place a wide piece of painters tape along the dimple in the firewall heater core cover as shown.


Using the Big Block Heater Core Cover Plate as a template, hold it along the dimple on your existing cover as shown. The left side of the template should line up with the outside crease in the cover. Use a marker to identify the center of each hole on the painters tape.


Remove the template and use a 1 inch hole saw to drill the holes. Note: You can enlarge the holes as needed with a round metal file when installing the big block heater core.






You can use the original small block heater core retaining clips to hold the big block heater core in place, but you will need to modify/file the clip that is next to the big block heater core tubes as shown.


I also installed some insulation between the new heater core and the interior heater core box to keep the heater core from rattling.

You should also install something to block/cover the original holes in the firewall that the small block heater tubes went thru.

Completed Installation


P.S. I updated my signature (... but I don't mind being called RifRaf :D)
 

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When I redid my 69 Nova back in 1991, I yanked the heater core and associated hardware out.. There was never going to be a need for a heater,lol...
 

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You can get to it on either side. I prefer under the hood as you will end up doing a lot of cursing when working up under the dash. If you pull the cover off under the hood you can expose it. Yeah it is over simplified because my fender is off but it still isn't that bad. Remove the clip on the left then you can work it out. When replacing it make sure the heater core slides under the clips on the right. The clip is designed to slide the core in and out.
I agree with Mark. I changed my 72 core years ago and removing the inner fender is so much easier than removing the front seat (bench), glovebox liner, CABLES and wiring, and generally working upside down. But to each his own!
 

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Discussion Starter #12
Thanks for all the input guys!

My buddy has a 71 Chevelle and he said he pulled his inner fender to get to his. Seems like that might be easier, but I don't know. I may try to get to it later this summer/fall. For now it's bypassed and isn't leaking anymore.

I rarely use the heater either, but it is nice to have in the fall when it cools down a bit and you go for a cruise. I take my kids sometimes and they get cold easy. I also don't like having too many non-working things on my car.
 

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If memory serves me right, to remove the core from under the hood, the Chilton Manual says to drill a hole in the passenger side inner wheel well so you can get to the last nut holding the blower case to the firewall.. I did this when I was 16 back in 1966 while changing the heater core on my Mom's 65 Impala. You then used a rubber plug to plug the hole.. Could be the same on a Nova..
 

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Carl

It's really not too bad to change out.

My Nova - Factory a/c car -- with the suit-case still under my hood.
(I did remove my Right fender for my install --- BUT --- I had a dent there where the "NOVA" script is on the fender. I wanted to knock-out-that-dent .... see what I mean).
For Me It was very easy to remove my R/S front fender (I'm an ol' body - man anyway.... plus -- on A/C cars , you have an A/C hose going through the rt. side inner skirt (under the battery) to the A/C drier.

You can leave the R/S fender on the car ---- but ---- the 'inner skirt' is very easy too "just drop down & let it rest there ... or remove completely. No re-alignment needed to the fender.

I did-not remove my front seat --- (your choice == easier). I have a rubber floor mat --- use the towels / rags.
I DID remove my "glove box liner" , so the inside box would give me room too remove my 'heater control cables" ------ may-be mark each cable at the mount point ... helps re-installing, to get the correct
"pull action" , the same as before.

Think about it --- I did NOT have any "rebuild heater box parts" ---
(depends) you might want too buy those 'PARTS' before hand ..... I did buy a box of '3 M strip-calk' , and used that for inside my heater-box. Thing is -- you may not know what's Broken (maybe / maybe nothing) (clip, plenum flap door and core outlet tube seals) ...
as we say : it's your car --- but, not a bad idea to have parts on-hand.
Because --- this is one job .. you only want too do once.

again, not a hard job , easy too do --- GET the CORRECT Heater Core , is the main chore. And, at some point (if you drive very often) , you might need "defrosters" ... I'm just saying.

NOTE :Removing the Glove-Box Liner Helps SEE - WHAT you NEED to SEE -- Pulling your inside Heater Unit from under your Dash.
Also, I DID remove my Glove-Box Door (just too get it outa my way ).
I DID USE the "3M Strip-clalk to re-seal my inside "Box back on to the inside Firewall' .

All really Good information ..... go for it ..... before the cold sets-in.
and, have Fun .....

The choice for changing to BB heater box 'mod' is interesting ... but ... my Nova is only 'Six-banger' (and, will stay I-6 as long as I have it) . .................... jim
 
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