# Heater Core Replacement For 1966 Gto



## take5 (Aug 9, 2009)

I Am Restoring 1966 Gto And Need To Identify Best Way To Complete Replacement Of The Heater Core.
Is It Necessary To Remove The Right Fender, Front Bumper, And Possibly The Hood To Get To The Heater Core. 
Let Me Know & Thanks


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## 1970 Lemans (Jul 25, 2009)

I recently replaced the heater core of my '70 (with ac) vehicle. The heater core is, of course, removed from inside the vehicle with the heater box (after removing the duct work and lower dash panel). The heater box was held in place with two screws and 4 studs. The screws (in center of heater box) were easily removed from the inside. The nuts for 3 of the 4 studs were also easily removed on the engine side. The nut for the fourth stud (lower right) was behind the inner fender well. There are three ways to deal with this that I am aware of.

One way to access it is as you suggest. 

A second way, as detailed by the Pontiac service manual is to air chisel out an inner fender well access panel that was speicifically introduced for this purpose.

I went a third route. That is, I elected to bore out the remaining stud from the inside using a 1/4 inch drill bit. As soon as I got through, the stud just fell out, thus freeing up the heater box. I didn't feel I needed to replace the stud with anything as the heater box seems quite secure with the remaining fasteners, though I suppose one could use a body screw. Obviously, if you are doing a concourse resto- this may not be desirable, but the blemish (hole) on the heater box is really not visible unless you stick your head down below the seat cushion.


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## geeteeohguy (Feb 2, 2008)

There is one stud between the fender and fenderwell that is almost impossible to access with the fender on. But, it can be done. Also, being that it's a '66, chances are that it's had the core replaced more than once, and that the one hard-to-get-to nut was left off on the re-install. Try the easy fasteners on the heater box, and see if it doesn't come off. Good luck.


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## take5 (Aug 9, 2009)

My thanks to both 1970 Lemans & GTO Guy for your responses, information, etc.
By way of background it appears from the 1970 Lemans that Pontiac Division made improvements for changing out heater core's as needed.
I picked up a GM Pontiac shop manuel for my 1966 GTO from Year One and believe it or not this official shop manuel states to drill a 1 inch hole through the fender wheel skirt to access the bolt for removal. The major difficulty here is not knowing the exact location to drill, there is no way of knowing & the hit or miss approach leaves a great deal to be desired.
Thanks also to GTO Guy with removal via easy fasteners on the heater box from the engine compartment. This heater core is the original and will be the first to be replaced.
I've owned the 1966 GTO since December of 1967 and it was built in Fremont, CA.
When the heater core began dripping under the glove box I just re-routed the heater hose on the engine and by passed the heater core. For the most part this GTO has been parked and not driven. As I said, I am now getting going with restoration.
This GTO has the California mandated "Smog-Pump" also known as "Air-Injection Reactor"
complete with gulp valve and all hoses connecting back into PCV.
Let me know, but this is no longer needed ( I believe California required these to be working for a period of 25 years to get your CA smog certificate ) and I am planning on removing this Smog-Pump & adjust timing.
One last item needed. How is the best way to remove right fender?
Will this invlove hood & front bumper?
At this point getting to the needed bolt for removal and your input is appreciated.


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## 1970 Lemans (Jul 25, 2009)

I've never removed the front fender so I couldn't walk you through this. One general thing I would suggest though. Since you aren't re-finishing the fender, in addition to making sure that you note the location of any body shims, before removing or loosening anything, I might suggest running stretches of masking or painters tape at junction points (like between the fender and door), drawing a mark on the tape with a magic marker and then cut at the seams and through the lines with a razor blade. This helps take some of the guess work out of re-alignment. I used this when I had to remove my rear bumper and I found it a useful re-attachment technique/guide.


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## take5 (Aug 9, 2009)

Knowing what to do & how to do it is worth a great deal. Thanks for letting me get a handle on this.


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## geeteeohguy (Feb 2, 2008)

Take5: Though the State of California is no longer testing 1975 and earlier vehicles every two years, all registered vehicles from 1966-1976 are required to have their original emissions equipment installed and functioning. If you got pulled over for a roadside inspection, you would be required to have the smog stuff your car came with. It is highly unlikely this would happen, as you know better than to tear it up in front of the law, and it is even less likely that a police officer, born in 1985, even KNOWS what a 389 V8 IS, let alone what it's supposed to have. Do NOT throw that smog stuff away. You can remove the fender without pulling the bumper, but be careful. use masking tape on edges to protect the paint. If it were me, I'd pull the inner fender well (wheel house) and do it that way. Leave the fender and its perfect, factory-fit alignment alone. If you've never r&r's a fender, and tried to line up the gaps, you're better off. It's a lot of work. It's great to have a fellow member who's been driving these cars since they were new. I've been driving mine for 30 years, not 40, and bought them when they were cheap, used, gas hogs. My '65 hardtop was built in Fremont on 4/29/65. We're all here to help.


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## take5 (Aug 9, 2009)

GTO Guy - Thanks for the background on the "Smog-Pump".
My 1966 GTO has been virtually in moth balls for the last 30 years & has 115,000 miles.
When I was still living in California I did have to replace the "gulp-valve" and Smog-Pump to pass a smog certificate inspection in 1987.
I now live in Tennessee and no requirement to keep this smog-pump. 
From an engine performance and running standpoint would it not be an improvement to take this off the engine & adjust the timing?
Is there any monetary value or market for an operating Smog-Pump system.
Would it be a good or bad idea to keep this smog-pump system?
As you know I am now restoring this GTO to the road status it has earned and truly deserves.
As a footnote I found a company located in Fresno, CA by the name of "Wheel Vintiques"
that have stock looking Rally I wheels that will go on my "66.
Keep me posted & thanks.


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## Too Many Projects (Nov 15, 2008)

As has been said, you can remove the fasteners for the inner wheel well and move it aside enough to access the fastener behind it. No need to mess with the fender. 
The smog equipment you remove may have a significant value to the 100% original restorers but then you won't have it, if you decide to return it to original. I, would keep EVERY piece you remove/replace from that car until it goes to the next owner (yes, there will be one sometime). The value of your car is much greater in original form.


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## geeteeohguy (Feb 2, 2008)

Take5, A friend of mine had the same smog equipment on a CA '66 GTO...the entire set-up for a tri-power equipped car. He got $1500 for it EIGHTEEN years ago, when these cars were worth about 10k restored. KEEP THE EQUIPMENT!!! Non CA cars had pipe plugs in the AIR ports at the ends of the cyl heads. I would remove the equipment, store it safely, and enjoy your car. Conincidentally, my '67 convertible is from Murpheesboro, Tennessee....I bought it in 1983 with Tennessee plates on it! It has NO smog stuff, and thankfully, does not need it 'cuz it's a federal car!!! Have fun with your project, and keep us posted!!


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## paly57 (Jul 27, 2008)

Take 5, there should be a dimple on the firewall side of fender wheel skirt which locates where you should drill the 1 inch hole. If you do this there is no need to remove the fender skirt.


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## kkosche (Dec 13, 2021)

I removed my heater core in my 1966 GTO today. It is a factory A/C car, original owner, stored for 40 years, well documented. Below are a few comments about how this went for me:

1. The factory manual talks about "6 nuts" . . mine only has 5 in the engine bay. 3 along the bottom (including the one tucked up between the fender and inner fender; and 2 on the top.

2. The bolt tucked up between the fender / inner fender really was not that bad. Hit each nut with some WD40 type of product, and got on the one in question with a ratchet end wrench. I could even jam both hands in there and take the last few threads off by hand, and retrieve the speed nut. Yes there IS a dimple on that inner fender well if you really feel the need to break out the hole saw . . . but in my situation that would have been completely unnecessary. 

3. What did take me an hour to figure out was that on the upper nut, nearest the center of the car (I attempted to add two pictures to this post, not sure if they will come through or not, happy to email, just PM me) . . . this stud passes through BOTH the firewall, and the engine bay metal duct work AND there was a round metal disc threaded on to the stud, tight against the firewall, and the engine bay metal duct work over the top, THEN the speed nut. I ended up taking out the 3-4 sheet metal screws holding the upper engine bay metal duct work so it would be loose enough to move off the stud so I can take a closer look. Gentle prying with a small screw driver, and a pair of needle nose pliers and the all was well.

I wish you the very best with your projects!


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