#1  
Old 10-06-2019, 09:58 AM
pilot737 pilot737 is offline
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Default Heater core replacement 67 GTO

I'm about to attempt to replace the heater core. Any advice is welcome.

Shop manual says remove glove box and disconnect control cables.
Remove six nuts from heater assembly.

Also says may not be able to access one of the nuts without cutting a hole in fender skirt... but someone mention before that shouldn't be necessary.

Anyone with experience of this remove/replace please offer help.

Reason for change is previous owner capped off core so I suspect it leaks. I asked him and he said "no" but he lied about other things so I don't trust him.

  #2  
Old 10-06-2019, 10:24 AM
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Quote:
Originally Posted by pilot737 View Post
I'm about to attempt to replace the heater core. Any advice is welcome.

Shop manual says remove glove box and disconnect control cables.
Remove six nuts from heater assembly.

Also says may not be able to access one of the nuts without cutting a hole in fender skirt... but someone mention before that shouldn't be necessary.

Anyone with experience of this remove/replace please offer help.

Reason for change is previous owner capped off core so I suspect it leaks. I asked him and he said "no" but he lied about other things so I don't trust him.
I hope others with more knowledge will contribute to this thread, there at least a couple of others I recall that address this topic. My personal experience with a 66 GTO was the outboard nut (above the inner fender skirt) could not be reached with any combination of socket extension/body contortion that I came up with. Rather than cut a whole I chose to remove the fender completely. Others have reported they were successful without doing either the hole or fender removal.
Good Luck.
Mike Pearson

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  #3  
Old 10-06-2019, 11:35 AM
pilot737 pilot737 is offline
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Default More info

Okay, upon further inspection, it seems nearly impossible to access two of the nuts without removing the fender skirt.

Is it difficult to remove fender skirt after wheel is removed?

Secondly, inspecting from the inside, it appears from these photos, there was a leaking issue before the system was bypassed. (There is rust on the nipple and the carpet.)

What is the purpose of the nipple piece on the bottom of the heater box?
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Old 10-06-2019, 11:59 AM
Jonsie Jonsie is offline
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Seems to me the 'nipple' serves as a pivot for a door inside the box, but it's been a long time since I worked on my '66 box

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Old 10-06-2019, 04:20 PM
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I think that I removed the nuts on the inner fender and rotated the fender to access the nuts. That was 9 years ago so I might be a little fuzzy on that.

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Old 10-06-2019, 10:12 PM
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I also unbolted the fender liner and dropped it out of the way to replace the heater core in my car. And, while I had it out of the way I replaced the blower motor. My car is A/C equipped

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Old 11-24-2019, 10:28 AM
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Default heater control cable

I decided not to tackle this myself. The shop did it recently and drilled a hole in the fender skirt to access the difficult-to-reach nut. When I asked "how did you know where to drill?"...he said there was a 'dimple' in the skirt that clued him to the drill location.

Back together and have heat now! But a small issue I wanted to ask about...

I can move the temp selector to the 'off' position and it feels like it moves in a detent at the end of travel. However, on the other side (warmer), it doesn't travel all the way (shown in picture). Should it travel to the stop or not necessarily?

Does it look like the cable is connected properly?
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Old 11-24-2019, 12:36 PM
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According to my service manual you should have a slight amount of "spring back" at the end of the levers travel, "not to exceed 1/8 of an inch". You can adjust that by turning that knurled plastic "turnbuckle" just to the left of the cable mounting bolt.

Edit: If that is the original 50 year old cable that's never been adjusted the turnbuckle may not want to move. Be careful to avoid breaking anything.

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Last edited by richardk; 11-24-2019 at 12:47 PM.
  #9  
Old 11-29-2019, 07:27 PM
xsram67 xsram67 is offline
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Default heater nuts.

The speed nuts can be accessed but be prepared to spend up to 1/2 hrs per nut. Small hands and small 3/8 wrench or ignition wrench will work. I did mine on my Gto and it's a PITA. I Remember doing the same on my 64 Buick Wildcat when I was a kid. Small ratcheting wrench may make it easier.

  #10  
Old 11-29-2019, 08:01 PM
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Quote:
Originally Posted by xsram67 View Post
The speed nuts can be accessed but be prepared to spend up to 1/2 hrs per nut. Small hands and small 3/8 wrench or ignition wrench will work. I did mine on my Gto and it's a PITA. I Remember doing the same on my 64 Buick Wildcat when I was a kid. Small ratcheting wrench may make it easier.
What nuts are you guys talking about that are hard to get to ? Could someone post a picture

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Old 11-29-2019, 11:13 PM
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Quote:
Originally Posted by gto19 View Post
What nuts are you guys talking about that are hard to get to ? Could someone post a picture
XSram67 is talking about the ones in the engine compartment. He either didn't realize you already had it done, or, more likely, he offered up some info for the next person that goes down this path. HTH.

PS- look for a mild kink in those heater control cables, it doesn't take very much to restrict travel

  #12  
Old 11-30-2019, 10:42 PM
wbnapier wbnapier is offline
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My heater controls were broken and I had to remove the unit to diagnosis and fix it. It isn't that hard, but I removed both front seats and placed a foam matt down so I could comfortably lay on my back and work from both the passenger seat and driver's seat without issues. I also had magnetic flashlights set up and a headlamp.

I have a real small mini ratchet which was helpful. The speed nuts weren't too bad. Don't forget the light bulb in there. You might as well change it too.

I remember that I bought new cables for the hell of it, but ended up only using 2 of 3. There was some issue with how the repop cables fasten and work with the control unit that I didn't like.

Once you remove the control unit, you can see how it all works and it is pretty easy to figure out what's going on.

The cables are adjustable and you can make sure your travel distance is good.

I remember that it is important to note where the cables route.

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  #13  
Old 12-26-2019, 10:38 AM
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Just curious. What’s the best heater core to buy when it does fail ?

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Old 12-26-2019, 11:08 AM
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Originally Posted by gto19 View Post
Just curious. What’s the best heater core to buy when it does fail ?
http://www.oreillyauto.com/site/c/se...GTO&vi=5152716

That same thread had at least one more endorsement for the Murray heater core.

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Old 12-26-2019, 11:30 AM
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Ok your link doesn’t work but your saying a Murray heater core from orielys

Thanks

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Old 12-26-2019, 06:35 PM
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Quote:
Originally Posted by gto19 View Post
Ok your link doesn’t work but your saying a Murray heater core from orielys

Thanks
Sorry, that link was copied from a 2013 thread so O'Reilly's part number may have changed, but yes, both posts in that thread (and I'm thinking in another one that I cannot find) spoke highly of the Murray heater core. Don't know if other supply houses sell the Murray core, I have always had good luck with O'Reilly.

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  #17  
Old 12-28-2019, 06:29 PM
pilot737 pilot737 is offline
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Default missing screws for defrost ducting

After heater core replacement, I notice a couple missing screws. One is just above the center console where the plastic defrost ducting connects to the heater box...

and the other is way up high where the plastic ducting connects to the underside of dash panel. (this picture is taken upside down while laying on my back.)

Anyone know what type/size screws? (I imagine they both need a washer also.)

67 GTO (no AC)
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Last edited by pilot737; 12-28-2019 at 06:30 PM. Reason: added text
  #18  
Old 12-30-2019, 04:00 PM
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Here is what the head of the screw looks like . I don’t wanna take it out since I’ll probably break it , loose it then my kid will eat it .
Looks like both screws your talking about are exactly the same and both have no washers
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