Radiator's Next !

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 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 .

Reply to
Snag
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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.

Reply to
Tim Wescott

Caterpillar Tractors sell an epoxy for repairing radiator cores. I've used it and the cure was apparently permanent, at least for the year or two until we finished that project. Or see:

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Reply to
John B.

Subsequent to my other post.

Try a search for "aluminum radiator leaks+electrolysis"

Reply to
John B.

Every single one of the cores leaked from the same area , the end tank join to the core or near there . It's not mechanical stress , can't be electrolysis , and I can't figure it out except that they got a bad run of product . It got to the point that the store I originally purchased it at refused to warrant it . Not a big deal now that the original is repaired , but I'm going to get one more under warrantee (or try ...) to keep on hand as a spare . This time it isn't coming from Memphis' warehouse stock , I'll pick it up here in Arkansas where I now live . The radiator came from the same source ... -- Snag

Reply to
Snag

WOW ! The evidence suggests that I need to do a complete flush of the system to stop this problem . From the info I got from that search string I'll be replacing the radiator too ... I'm wondering if I might need to use an alkaline product to neutralize the system along with that flush . This is my first experience with this problem ... and it didn't manifest until I replaced OEM brass components with aluminum . Makes me wish I still had the original radiator too . Thanks for the eye-opening education John ! -- Snag

Reply to
Snag

I wonder whether conventional radiator flush is alkaline or acidic?

Reply to
John B.

Check the msds. Gunk /Solder Seal rad flush is mostly potasium Hydroxide and Dodecybenzinesulfonic acid - it says to neutralizw spills with soda ash - so it is definitely an acid.

I used to use a half pound of baking soda to neutralaze afer an acid flush - and then re-rince with clean water before filling.

Reply to
clare

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