C4 Tech/Performance L98 Corvette and LT1 Corvette Technical Info, Internal Engine, External Engine

Heater core replacement

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Old Jan 22, 2026 | 07:02 AM
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Default Heater core replacement

I need to replace the heater core,and at the sametime get rid of the bose system and the breadbox. Any insight would be greatly appreciated
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Old Jan 22, 2026 | 09:19 AM
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You can try the "advanced search" feature of this site. There are literally hundreds of posts on heater core replacement. Some here also think that a google search finds the best posts here. For sure search Youtube for videos of the replacement. Make sure you post your year as there are some differences. Dan
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Old Jan 23, 2026 | 12:15 AM
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If you've never ripped the dash out of a car before, you might want to rethink replacing your heater core yourself.
It's not trivial.
Be forewarned, unless you are **** to an extreme, things will absolutely not go according to plan.

You've been warned.

Crabs
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Old Jan 23, 2026 | 07:00 AM
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I figured that it would be going down the rabbit hole.
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Old Jan 23, 2026 | 09:19 AM
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Recently did my core for the second time in the last 24 years. Both times I used the Fastguy method from the footwell.
Here is a quick rundown
Remove seat
Remove footwell panel
Remove ECM
Remove angled dash brace
Remove blend door motor
Remove duct going into heater core cover
Remove 5 screws around cover
Remove cover
Remove single screw and clip from top center of core and 2 screws from bottom bracket of core
Remove core
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Old Jan 23, 2026 | 01:46 PM
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You are in for some real fun. They built the whole damn car around the heater core. Do the above and stay patient.
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Old Mar 19, 2026 | 03:45 AM
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Make sure to get an aluminum replacement, though I'm guessing by now that's all you can get. As I think the main reason why the factory heater core fails is the brass corrodes at the solder joints. As least mine looked like it leaked out the joint where the tubes were soldered to the base. The replacement I used was all aluminum and has been working fine.
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Old Mar 19, 2026 | 09:16 AM
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Thanks for your response, I will definitely keep this in mind when I do this spring
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Old Mar 19, 2026 | 11:35 AM
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I replaced the heater core as well as the OEM radio and speakers in my 96 last year. I found lots of help here and put together an instructional document with pictures that “mandingo214” posted here on 3/2/12. I made a few additions with some items that were not mentioned. If you shoot me your email I can send you the document. It really isn't as bad as I thought it would be. Take your time and keep removed hardware in marked zip-lock bags.
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Old Mar 19, 2026 | 11:42 AM
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Magapin62@gmail.com Thank you in advance
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Old Mar 21, 2026 | 03:20 PM
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I replaced the heater core (HC) on my 1985 Corvette. I suspect the heater core failed shortly after I put in a new water pump.

Anyways, before starting the procedure to replace the heater core, I purchased an after market heater core and scope camera prior; so I would have everything required to do the job. However, when I was instaling the new aftermarket heater core, I had a very challenging time aligning the HC for the install. After some effort, I decided that it was not going to work for me.

I took the original heater core, that I just removed, to a very reputable shop and had them fully repair. Additionally, the shop mentioned for me to to bring in the heater water shut off valve for a hot tank steam cleaning too for no extra charge because it was suggested to me that this would be an opportune time to do a complete coolant cleanout of the system for any possible corrision or impurities. So, once I completed installing the repaired heater core, I replace the 2 hoses from the shut off valve to the firewall from the engine side, put in the freshly cleaned heater shutoff valve and completely drained all the coolant in the radiator. In the end, fresh coolant throughout the coolant system was the way I thought to go because all the time vested.

Last edited by Magnet; Mar 22, 2026 at 01:44 AM.
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