On Thu, 26 Sep 2013 14:41:27 -0500, Snag wrote:

I had a leak in my truck ('86 GMC 305 V8) heater core a couple (or 3 or
5 ...) of years back and instead of trying to repair it I just bought a
replacement from NAPA - cheap because my son works there (his employee
discount , nothing shady) . Cheap looking aluminum unit , but it lasted
a couple of years . The next one lasted less than 6 months ... and the
next 3 or 4 each lasted about a month . All properly installed , system
flush the first couple of times , but antifreeze ain't free .
The last one that failed is still in the heater box , though the hose
is
now routed from the engine straight into the radiator because it started
leaking while I was halfway home (halfway between Memphis and Mtn View)
. So now fall is coming on , winter will be here soon , and I'm not
particularly inclined to put another "lifetime warranted" NAPA unit in .
So what the hall , I still have the original , and it's out in the shop
in a box . Let's see where it's leaking ... and it turns out the leak is
in a place that's easy to get at to clean and resolder . Cleaned ,
soldered , and I just pressure tested it to 25 psi , which is a good bit
higher than system pressure .
I love it when something works out this well ! Now I need to pull the
radiator , it started leaking a few weeks ago - and this one is going to
be harder . Aluminum core with plastic tanks , and the water stain is
right in the center of the core . I need to see if it's a surface tube
or deep inside . Either way , there is really only one way to stop the
leak , and that's to cut/crimp the leaky tube . Shoot a wad of sillycone
in there before I crimp . If I had more experience and talent I might
try to TIG it , but those tubes are a lot thinner than I can currently
manage to weld without blowing holes .
Then there's the tick that started a few days ago ... High likelihood
it's
the fuel pump pushrod . Not sure yet if it's the pump failing or the cam
lobe , but it's also gotta be fixed before the snow flies .
--
Snag
Shade Tree Mechanic and Metalworking Hack .

Are you sure it's the NAPA cores, or is there something else going on?
Did they all break in the same place? Do you have mice in the truck with
carbide teeth?

I'd see if I could get a genny-U-wine GM heater core for the thing, and
see what a radiator shop says about the radiator, but I understand the
whole concept of "limited money" and what that does to one when the long-
term solution is too expensive for the short-term budget.

--

Tim Wescott
Wescott Design Services
http://www.wescottdesign.com