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Heater Core Restoration w/Photos

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Old 06-14-12, 04:36 PM
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Heater Core Restoration w/Photos

I recently restored my blower, evaporator, and heater core. The heater core was the trickiest by far.

Link to blower restoration: https://www.rx7club.com/3rd-generation-specific-1993-2002-16/c-blower-rebuild-w-photos-993190/
Link to evaporator restoration: https://www.rx7club.com/3rd-generation-specific-1993-2002-16/c-evaporator-rebuild-w-photos-993467/

Note: Take photos and pay attention how stuff goes together. This thing has a lot of little pieces so reassembly can be tricky.

Here's what we start off with. Note all of the rotting foam pieces.



The flaps that direct air flow are also covered in rotting foam. This stuff falls apart and flows out the vents in the car and it makes a mess.



There are several clips and screws holding the two halves together. First, remove all of the clips where the two halves meet. Then remove this screw:



Then remove the servo motor, and remove the screw in this hole underneath it:



Unlatch this little actuator arm:



Now you can pull the two halves apart to gain access to the air flow guides.

Attached Thumbnails Heater Core Restoration w/Photos-img_5255.jpg   Heater Core Restoration w/Photos-img_5254.jpg   Heater Core Restoration w/Photos-img_5260.jpg   Heater Core Restoration w/Photos-img_5261.jpg   Heater Core Restoration w/Photos-img_5263.jpg  

Heater Core Restoration w/Photos-img_5265.jpg  
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Old 06-14-12, 04:45 PM
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To remove the flaps, use a flat head screw driver to pull the little lock tab on the end of the shaft, then slide the flap out. For some reason I didn't realize you could do this when I did the A/C blower. It definitely makes it easier to take the flap out completely.



Scrub off all of the old foam. Originally I tried just sticking some adhesive-backed rubber on there, but it didn't stick at all. So I tried a plastic glue, which didn't work at all. I ended up using JB Weld, believe it or not. That stuff held it better than anything else.

Some of the flaps are made from metal, however, and on those the adhesive-backed foam works fine.

The foam I used is Part # 93625K294 from McMaster.com. It's a little harder than I would have liked, so I might have tried something softer if I were to do it again.

Here are the plastic ones after replacing the foam. There are also a couple of metal ones.



I also pulled the little copper radiator and cleaned it up:



Reassembled the whole thing and added new rubber gasket around the outer seals. I used McMaster.com part # 93725K72 which worked perfectly.

Attached Thumbnails Heater Core Restoration w/Photos-img_5266.jpg   Heater Core Restoration w/Photos-img_5283.jpg   Heater Core Restoration w/Photos-img_5286.jpg   Heater Core Restoration w/Photos-img_5295.jpg  
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Old 06-14-12, 04:54 PM
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On a side note, I also replaced all the foam rubber and anti-rattle foam on my dash.

Also, JB weld works very well for fixing any cracks and broken plastic pieces. In some places I used plastic "weld" glue, and then covered it in JB weld later. JB weld gets very hard so it works great for reinforcing the repair.

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Old 06-14-12, 05:17 PM
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You mention cleaning up the heater core, why wouldn't you just replace it considering how much of a PITA it is to replace after everything is assembled?
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Old 06-14-12, 05:35 PM
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Originally Posted by RENESISFD View Post
You mention cleaning up the heater core, why wouldn't you just replace it considering how much of a PITA it is to replace after everything is assembled?
You mean replacing just the copper radiator? It's not available separately, and at least on my car it was in good condition and wasn't leaking or anything. The only thing that can really go wrong with it is a leak. I did replace one of the pipes though, because it was damaged when I pulled the whole assembly.

You can buy a whole new heater core assembly. It's $452.10, if they're still even available. Mazda has been discontinuing a lot of parts lately.
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Old 06-14-12, 07:04 PM
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Michael-

Apologize for being off topic but are you no longer making your Trailing Arms and Toe Links? I have everything you offer suspension wise for the FD but was going to refer someone else to your site and they don't seem to be on there anymore.
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Old 06-14-12, 07:13 PM
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Originally Posted by Gringo Grande View Post
Michael-

Apologize for being off topic but are you no longer making your Trailing Arms and Toe Links? I have everything you offer suspension wise for the FD but was going to refer someone else to your site and they don't seem to be on there anymore.
Yeah, we discontinued them, unfortunately. They weren't selling very well and there are several other companies making them already, so we decided to discontinue them and put our resources towards focusing on new and innovative products.
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Old 11-04-12, 06:30 PM
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And incase you dont take pictures like me and get confused during the reassembly.
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Old 11-04-12, 08:10 PM
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I remember seeing this thread earlier this summer and thought, "WOW! That is impressive!"
Pretty kick-*** level of attention to detail.
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Old 11-04-12, 08:38 PM
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This is pretty awesome. About how much did you spend on those various things and how did you come to the decisions you made on what thickness to buy? Just in case they change part numbers Id like to understand you though process on why you selected what you selected.
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Old 02-18-13, 11:41 AM
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Originally Posted by Reno_NVFD View Post
This is pretty awesome. About how much did you spend on those various things and how did you come to the decisions you made on what thickness to buy? Just in case they change part numbers Id like to understand you though process on why you selected what you selected.
Honestly, I'm not sure how much I spent. I did buy a couple of different types of foam to see what worked best. I probably spend around $100 in materials.

Basically, I just took it apart, and tried to figure out what the original thickness of the foam was. You can measure the width of it easily, but the thickness is a little difficult to figure out when the foam is flattened out and disintegrating. That 1/4" thickness worked well though. Then you kind of have to guess on the correct firmness based on the descriptions on McMaster.com. Also look at the different types of foam and get something that has a good temperature range, resiliency, etc for a reasonable price. You want something that will hopefully last longer than the OEM stuff. Closed-cell foam is also typically better than open cell.
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Old 10-06-13, 05:27 PM
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Page G33? Where is this page G33 at? In the service manual G is the section for engine electrical components... Which manual is this? Because I have no clue how the heating system works and I want to know what all goes into it.
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Old 10-06-13, 09:17 PM
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Originally Posted by StreetRage View Post
Page G33? Where is this page G33 at? In the service manual G is the section for engine electrical components... Which manual is this? Because I have no clue how the heating system works and I want to know what all goes into it.
Body Electrical Troubleshooting Manual
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Old 09-27-16, 04:52 PM
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Replacement Copper Pipes / Tubes

Originally Posted by RaceDriver7 View Post
You mean replacing just the copper radiator? It's not available separately, and at least on my car it was in good condition and wasn't leaking or anything. The only thing that can really go wrong with it is a leak. I did replace one of the pipes though, because it was damaged when I pulled the whole assembly.

You can buy a whole new heater core assembly. It's $452.10, if they're still even available. Mazda has been discontinuing a lot of parts lately.
Where did you buy replacement pipes? Thanks!
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Old 09-27-16, 07:15 PM
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Originally Posted by WHIPSrx7 View Post
Where did you buy replacement pipes? Thanks!
Mazdamotorsports.com


PIPE, HEATER /NLA
Part No: FD01-61-A15A

I only replaced that one pipe but you can probably find the other one on there.
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Old 09-27-16, 08:31 PM
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Thanks for the write up.
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Old 05-06-17, 01:44 PM
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First off, again, THANK YOU so much for pioneering this procedure.

We're TOTALLY rebuilding an FD here in Pensacola, going damn near down to the shell and back up. Of course I'm going to spend the time to do the heater core and everything!

JUST got done putting the heater core back together. Here's a few tricks and tips I figured out -

- For the foam on the doors, I used McMaster-Carr part number 86025K56. It's a 1/4" thick soft foam with excellent rebound and it's closed cell. I'm hoping it will hold up well. The adhesive is very strong on it and you get a BIG roll, enough to do more than one car.

- For the plastic doors, I cleaned the hell out of them and got all the old foam off. I then masked up the pivot points and sprayed 3M high strength contact adhesive on the panel. Let it set up then applied the foam. So far so good.

- For the "bumps" on the plastic panels, after adhering the new foam, I used an XActo knife to trim around the little bumps and cut the foam out. Then, I used a small Dynamat roller to roll the foam down and insure that it was well stuck on and pushed down around the foam bumps.

- On the other side, there's a raised square in the middle of the panel. Again, foam down then used the XActo knife to trim around both sides of the raised square then used the roller to press down. Some of the foam stuck up so I trimmed it off.

- This thread is VERY useful for pictures to re-assemble. It's a real maze of parts, the big one is make sure you have the flapper doors in the right position and orientation. I had one that was 180 out, I had to pull it apart again to re-orient. Make sure everything is where it should be first before putting the motors and linkage back on.

- I got a small tube of white lithium grease to grease all the moving parts, that's what the factory did and most of it has broken down over time. May not make a huge difference but it's worth doing.

I've also done the blower motor using RaceDriver7's guide, I recommend starting small and getting comfortable before doing the heater core. The heater core is NO JOKE of a job. Get a big, clean area to work on as well, I put towels down and used the dining room table (the wife loved it ).

Dale
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Old 04-03-18, 10:32 AM
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Originally Posted by DaleClark View Post
First off, again, THANK YOU so much for pioneering this procedure.

We're TOTALLY rebuilding an FD here in Pensacola, going damn near down to the shell and back up. Of course I'm going to spend the time to do the heater core and everything!

JUST got done putting the heater core back together. Here's a few tricks and tips I figured out -

- For the foam on the doors, I used McMaster-Carr part number 86025K56. It's a 1/4" thick soft foam with excellent rebound and it's closed cell. I'm hoping it will hold up well. The adhesive is very strong on it and you get a BIG roll, enough to do more than one car.

- For the plastic doors, I cleaned the hell out of them and got all the old foam off. I then masked up the pivot points and sprayed 3M high strength contact adhesive on the panel. Let it set up then applied the foam. So far so good.

- For the "bumps" on the plastic panels, after adhering the new foam, I used an XActo knife to trim around the little bumps and cut the foam out. Then, I used a small Dynamat roller to roll the foam down and insure that it was well stuck on and pushed down around the foam bumps.

- On the other side, there's a raised square in the middle of the panel. Again, foam down then used the XActo knife to trim around both sides of the raised square then used the roller to press down. Some of the foam stuck up so I trimmed it off.

- This thread is VERY useful for pictures to re-assemble. It's a real maze of parts, the big one is make sure you have the flapper doors in the right position and orientation. I had one that was 180 out, I had to pull it apart again to re-orient. Make sure everything is where it should be first before putting the motors and linkage back on.

- I got a small tube of white lithium grease to grease all the moving parts, that's what the factory did and most of it has broken down over time. May not make a huge difference but it's worth doing.

I've also done the blower motor using RaceDriver7's guide, I recommend starting small and getting comfortable before doing the heater core. The heater core is NO JOKE of a job. Get a big, clean area to work on as well, I put towels down and used the dining room table (the wife loved it ).

Dale
I used the 5/32 firmer foam that came up when I searched the 93625K294 part number from the original post, which is similar to what I have seen recommended by some other members in the other two hvac restoration threads, but it sounds like maybe 1/4th was the necessary size? It seemed like the flappers were making contact with the foam I applied, but after reading this I am wondering if I should apply a small top layer of compressible foam to the 5/32 foam I have already used. Any thoughts?
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