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 .

Subsequent to my other post.

Try a search for "aluminum radiator leaks+electrolysis"
--
Cheers,

John B.