Heater Core is out - finally
Thread Starter
Racer
Joined: Jul 2005
Posts: 433
Likes: 14
From: GA
Heater Core is out - finally
I think I would put removing the heater core a bigger PITA than removing the trailing arms. I would like to have seen how GM installed these heater/AC systems in a C3 an a matter of minutes. Anyway... went to install the "Made in Mexico" heater core I got from Corvette Central and it "almost" fits. The pipes are about 1/4" too close and won't fit on the "locator pad" or allow the "M" clamp to be used which cause the mounting straps to be misaligned. I think if I modify the "locator pad" it will work. You would think that with all the manufacturing technology available that someone could make an "exact" duplicate of the Harrison heater core. I also ordered a complete" heater/AC gasket kit which came from ZIP. Has anyone used this kit? The instructions are pretty poor.. not sure where the "gray foam gasket" goes or the "black foam" pipe seal. It seams like the core should mount on a gasket/cushion but nothing in the "complete kit". You guys that are doing this - get you gasket kit from Dr. Rebuild - I wish I had.
Le Mans Master
Joined: Apr 2005
Posts: 6,354
Likes: 424
From: Seattle Area WA
Check out my article on these heater cores. Same exact problem, I used a propane torch and sliver solder to align the pipes. I think you'll find that the dull grey solder used will crack easily too, at least mine did.
http://blog.scottsvettetalk.com/2007...eater-box.aspx
http://blog.scottsvettetalk.com/2007...eater-box.aspx
Instructor
Joined: May 2007
Posts: 149
Likes: 0
From: jarrett north carolina
heater core
man,i tried 3 new cores on my 76. non would fit,i finally took the original harrison core to a radiator shop and had a new core made ,it fit perfectly. do you know where i can buy the inner heater box bolts,4 of them?----thanks and good luck---john
Thread Starter
Racer
Joined: Jul 2005
Posts: 433
Likes: 14
From: GA
I got it to mount OK, just had to "massage" the pad a little and rebend the clamp a little bit. The end of the pipes are about 1/4'' closer together than the Harrison but the hoses should go on OK. If it doesn't go back in OK, I'll get the original recorded. Thanks.
Drifting
Joined: Oct 2007
Posts: 1,458
Likes: 1
From: Collinsville MS
St. Jude Donor '08
I ordered one for mine 2 weeks ago, had to wait a week for it to come in. When I take it out of the box, this is what I got. My old one is on the right:
I carried it back, they looked at it and it and wanted to know what was wrong with it. So I explained the difference between straight and BENT!
They ordered another one, it looked nothing like the original, at least this one resembled it, minus the curve in it.
I carried it back, they looked at it and it and wanted to know what was wrong with it. So I explained the difference between straight and BENT!
They ordered another one, it looked nothing like the original, at least this one resembled it, minus the curve in it.
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Pro
Joined: Sep 2007
Posts: 735
Likes: 1
From: Harleysville PA
Does GM carry the original heather cores? I need one for my 69 and was going to order one from corvette central but after reading this post will either buy and OEm or have the old one recored. Dan
Melting Slicks
Joined: Jul 2005
Posts: 2,740
Likes: 3
From: Aurora Ontario
I'll call my local GM guy. they are pretty good at looking for me. Yours with a/c or without?
Jim
Racer
Joined: Feb 2008
Posts: 427
Likes: 32
From: North Alabama
St. Jude Donor '24-'26
Le Mans Master
Joined: Mar 2000
Posts: 9,127
Likes: 2,326
From: Pottsville, PA. USA Home Of America's Oldest Brewery Yuengling
Remember Nothing Fits Like OEM !!!!!!!!!!!!!!!!!
Le Mans Master
Joined: Mar 2000
Posts: 9,127
Likes: 2,326
From: Pottsville, PA. USA Home Of America's Oldest Brewery Yuengling
When you put the heater case back in the car and hook up the vacuum hoses start the car and move the control dial to make sure all of the doors open and close and the air comes out where it should. Do this before installing the radio and center gauges.
PS Jim
I have installed over 30 heater cores in these C3 cars so I know all of the pitfalls. If you get stuck knowing where all the vacuum hoses go Doc Rebuild has drawings on his website under a/c vacuum hoses. Now talk about a puss case try installing a heat core in a 1984-1996 Vette. This is a job you will want to shoot yourself!!!!!!!!!!!
Last edited by Corvette ED; Feb 25, 2008 at 06:45 PM.
Drifting
Joined: Oct 2007
Posts: 1,458
Likes: 1
From: Collinsville MS
St. Jude Donor '08
this is off another website for testing the heater core:
Whether you are using an old core or a new replacement, it pays to test it for leaks. Filling it with water won't do the job, however, since most heater cores only leak under pressure.
There's an easy way to test your core, and one that requires no equipment. All you need to do is press your thumb over one hose outlet and suck on the other one (you might want to clean it off first!) Suck on the pipe firmly to create a substantial vacuum, then hold for a few seconds to see if the vacuum goes away. You'll know if it does, and that means the core will leak.
How effective is this test, you might ask? Well, at sea level you will be able to create a vacuum of nearly one atmosphere, which is equal to around 14 psi. That just happens to be very close to the operating pressure in your cooling system. If the core can take a vacuum, it can take the cooling system's pressure.
Whether you are using an old core or a new replacement, it pays to test it for leaks. Filling it with water won't do the job, however, since most heater cores only leak under pressure.
There's an easy way to test your core, and one that requires no equipment. All you need to do is press your thumb over one hose outlet and suck on the other one (you might want to clean it off first!) Suck on the pipe firmly to create a substantial vacuum, then hold for a few seconds to see if the vacuum goes away. You'll know if it does, and that means the core will leak.
How effective is this test, you might ask? Well, at sea level you will be able to create a vacuum of nearly one atmosphere, which is equal to around 14 psi. That just happens to be very close to the operating pressure in your cooling system. If the core can take a vacuum, it can take the cooling system's pressure.
Thread Starter
Racer
Joined: Jul 2005
Posts: 433
Likes: 14
From: GA
Ed,
I really do think R/R the heater core is more of a PITA than removing the T/A's. I ended up removing the shift plate, took out the AC/Heat controller before I could get the nuts off the studs, removed the brake console, console, and center guage cluster, all the ducts. Removed the AC evap housing and finally the heater housing. I guess the bright side of all this is that it will be easy to replace the AC/HTR vac hoses, maybe get the clock working and get every thing cleaned/painted before it goes back together.
L82, I'll try that test method - makes sense to me - thanks
I really do think R/R the heater core is more of a PITA than removing the T/A's. I ended up removing the shift plate, took out the AC/Heat controller before I could get the nuts off the studs, removed the brake console, console, and center guage cluster, all the ducts. Removed the AC evap housing and finally the heater housing. I guess the bright side of all this is that it will be easy to replace the AC/HTR vac hoses, maybe get the clock working and get every thing cleaned/painted before it goes back together.
L82, I'll try that test method - makes sense to me - thanks
Drifting
Joined: Oct 2007
Posts: 1,458
Likes: 1
From: Collinsville MS
St. Jude Donor '08
Jim,
I agree with your assessment. So far this has been the biggest PITA in the whole restoration. I pulled the ac box AND the dash, course Bubba had been in there before me and I wanted to be able to see everything to ensure it went back right.
I agree with your assessment. So far this has been the biggest PITA in the whole restoration. I pulled the ac box AND the dash, course Bubba had been in there before me and I wanted to be able to see everything to ensure it went back right.
Pro
Joined: Sep 2007
Posts: 735
Likes: 1
From: Harleysville PA
Great tip on the part number and checking with Chevy first as OEM is the way to go. Dan