A common problem with the fresh air heater on these old AD trucks is the heater core. They are almost always jacked and from what I've found, difficult to repair. The replacement is available through Classic Chevy Parts aka Chevy Duty but they want a hefty $170 for it. This is too expensive for my blood so I started looking for an alternate (cheaper) one available through the local parts store. I searched and searched through dimensions and ended up finding an aluminum one that is a little wider and thinner than the original. It was something that I could work with. Part number 398325 is the replacement and is a little cheaper at only $70. Here is the heater and original heater core. The replacement heater core comes with some lines that will need to be cut off in order to fit it into the box. After cutting the lines off, you'll need to attach some 90 degree bends. I found them in the local Ace Hardware and attached them with JB weld. One needed to be slightly cocked in order for hose routing. You can see them in the pic. Now the slight modification to the back of the box. There was originally two holes in the back that the original heater core stuck out. You need to drill a new exit hole ( the left one of the cluster of 3) and enlarge the top hole so that a 5/8 heater hose will fit through it. Here you can see the new heater core in with the 90's lined up. Next I used some foam sealing tape stuff from the hardware store to seal the edge of the heater core to the box to create a tight fit. And here it is all back together with the hose attached to the furthest port and running out of the box. Fits great and didn't take much modification to the box. Pic from the back where you can see the other 90 sticking out. And that's it. I'm sure it could have been done another way but this is how I did it and it works great. Nice to save some money too!
Sorry I don't know the application, I found it by the dimensions. I got this one from Advance Auto but Autozone lists it as well.
JB Weld may not work well w/anti-freeze. According to them. I had called on a seriously OT issue, & I was told that it would soften & eventually not hold pressure. Just how long that might be, they didn't say. FWIW. Marcus...
I read the back of all the packages and the original cold weld formula says "J-B Weld has a tensile strength of 3960 PSI and sets to a hard bond overnight. It can withstand temperatures up to 550ºF when fully cured." The Qwik Set and others have lower PSI and temperature capabilities. Interesting, I guess I'll be the test market. The reason I chose it instead of soldering the pieces on, is that I read that it would be difficult to get the copper to seal to the aluminum. Worst case is when it starts leaking, I'll take it back out and try something else.
It looks great, and certainly was thinking "outside the box", so to speak. In addition to the JB Weld question, I also wonder about the hose to smooth copper fitting connection. Without a ridge, I would be concerned that eventually the hose will work off the fitting. Time will tell on both scores. Please keep us posted.
I was concerned about this too, but the factory core didn't have a ridge either. It was just a smooth copper joint. Like you said, time will tell. At least I have heat now.
Old thread i know, but for anyone else (like myself) hunting out info, heres a wee tip... No need to spend money on fancy copper fittings, you literally have two weldable 90 degree fitting on those bits of aluminum tube youre cutting off. So while you have your saw out, cut and use them, then solder/tig them there instead of jb weld. So simple even i can think of it! Fascinating!
Since this was brought back up I'll give a 4 year update. Still leak free and able to cook me out of the cab with the heat on.
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