What I learned during my heater rebuild (1 Viewer)

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Dec 13, 2012
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So, I had the center transmission hump off and figured it was a good time to rebuild my rusting front heater. Here are some of my observations and what I learned. This is from a 12/72 built 73 FJ40.

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It wasn't terrible but this is after soaking in rust remover, one side at a time. As you can tell it is more of a grey than a black and flat not shiny so locating an appropriate paint was hit and miss. I chose Rustoleum Metallic Flat Soft Iron. I also followed up the soak with a die grinder and wire wheels to remove as much rust as I could. I gave the body a coat of Rustoleum Rust Reformer before applying the color. The left end and internals were clean enough that I only applied the color coat and no Rust Reformer.

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The clip and screw holding the air diverter are factory original while everything else has been repainted. I think it is close but not an exact match.

Being frugal if you're nice or just plain cheap, I couldn't see spending what they wanted for a heater rebuild kit, a whole lot of money for basically some raw foam except for a few pieces. I did however buy a SOR trans hump gasket kit which had what turns out to have been plenty of extra foam to accomplish my heater rebuild.

I flushed the heater core with green muriatic acid, Klean-Strip brand which has less fumes than regular muriatic acid. Because it really didn't foam or bubble I'd let is soak for 15-30 min. and then see what spilled out. After several hours and several flushes when the particles stopped falling out I soaked it over night in plain water to ensure all the acid was neutralized before I started the assembly.

I forgot to mention that during disassembly it is important to note where all the foam is placed and be gentle with pieces that cannot be replaced. Also, take the time to straighten out the heater fins for optimum air flow and heat transfer.

It started out looking like this.

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Although the foam was in place on the side, it was brittle and shot. The end pieces are molded and were reusable but you need to be gentle with them.

Here it is after cleaning and applying new side foam.

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With everything cleaned and repainted it was time for assembly. Place the one end foam in the housing before inserting the core.

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(to be continued)
 
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With new foam on the sides of the core the fit was tight so expanding the case is a must to avoid tearing the foam.

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Then put the other molded foam over the end of the core and apply new foam.

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You can see from the photo that I did tear the upper right edge at the hole but nothing to keep it from being reused.

In this photo you can see how the foam strip on the end cover totally seals the air from the intake opening from getting past the end of the core and forces all of it through the core.

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To get the screws into the top two holes was a bit of a pain. All the new foam was preventing everything from lining up. I put an 18" 1/2" drive extension in my vise and placed the heater over it through the intake opening. By pressing down on the top of the case I was able to get the screws started. The bottom ones didn't resent any problem and were already in before I put in the top two.

When all was said and done this is what I had.

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Hopefully it will last another 41 years as the cost of the defroster hoses and square rubber duct were a killer. I hope this helps anyone else save a few bucks and makes your job easier. A lot cheaper than spending upwards of $500 for a new/rebuilt heater. :)
 
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Oct 17, 2011
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Nice job, and nice paint colour choice. I just did my '78 heater. The expanding clamp thingy you used would have been handy. I had a bit of a time getting the heater core to slide in without messing up the foam.
 

love2fly

Flying the Mountains of the NW
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I like your write up on the build with excellent photos. Nice job.
 
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Super job!--I didn't add so much foam in mine when I did it, but I think I should have--wish I'd seen you post before---
 
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Thanks guys!

On most of the grip type clamps you can usually reverse one end and you end up with a spreader. I actually used this trick to help muscle in my transmission.

I only put foam back where there was originally foam. The stuff from the SOR trans hump seal may have been slightly thicker and I believe it is closed cell foam instead of open cell foam which I believe was factory. The problem with open cell foam is that it allows water to to trapped easier where closed cell is more like sealed balloons or chambers which don't allow water to accumulate.

Now it's time to put a new seal in the fresh air cowl vent. Every wonder why they leak?

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Seems if you let the gunk build up it prevents the seal from actually sealing and also blocks the drain.
 
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That looks great. I've been reading up on freshening up mine as well. I was trying to research where to buy the foam in a local retail place maybe a homedepot or hobby lobby. Did you buy a rebuild kit. I was thinking I could source the foam for less than a vendor might sell it.

Now you might need to get newer heater hoses or refresh your old ones to match the great looking heater.
 
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. . . Did you buy a rebuild kit. . . . Now you might need to get newer heater hoses or refresh your old ones to match the great looking heater.

No rebuild kit. I had the trans hump off and picked up the SOR pre-cut/formed gasket kit. It has the adhesive back and there was enough scrap to do the heater. The heater kits I saw did not have adhesive backing except for the diverter plate and the thin piece at the top of the left end plate. I was able to get the diverter plate piece cut from a single piece but had to piece together a couple pieces of scrap to make other pieces I needed. Since it is all hidden that was perfectly fine with me, especially since it didn't cost me anything extra.

That paint looks great! What rust remover did you use?

I used Evapo-Rust. It seems to work fine and if you remove as much rust as possible before hand it works quicker. Some heavy rust requires leaving it over night or longer if the fluid is older and not new.
 
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That works out perfect for me, I was about to get the gasket and bolt kit for the trans tunnel from sor. im just waiting until i need a few things to make it worth ordering from them
 
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Well, finally got it installed.

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I found a neat device to help stop the short rear heater hose from crimping when formed into this tight return. It's made by Good Year and called E-Z Coil.

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The coils support the hose and prevent the collapse while the thin bar retains the shape it is bent into.
 
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Looks awesome. Couldn't you just cap those rear outlets?

I thought about it but couldn't find a product that was designed to cap the fittings. I thought about using vacuum caps but wasn't sure they would survive the heat and pressure. I also didn't want to solder them closed with copper pipe caps.

Where I live in So. Cal doesn't real need the rear heater but it's still on the shelf in case I ever decide to put it back in.
 
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I thought about it but couldn't find a product that was designed to cap the fittings. I thought about using vacuum caps but wasn't sure they would survive the heat and pressure. I also didn't want to solder them closed with copper pipe caps.

Where I live in So. Cal doesn't real need the rear heater but it's still on the shelf in case I ever decide to put it back in.

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I used these for a lot of of years after my rear heater core started leaking. When the front heater core went south, and I ditched heaters all together, I used the same caps on the engine.
 

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