I think it was Mark Price who came up with the best way to check something
like this under pressure at home... a bicycle inner tube clamped to the
inlet an outlet! Would be harder on a heater core, but cut a couple 1"
sections of heater hose and slip on the inlet/outlet then clamp the tube
over that, pump up to 20 psi, and see if there are any leaks. A little
water in the core (just a couple ounces) might make it easier to find the
leak, especially with a drop or two of soap in it. Pressure is always
better than vacuum for checking something like this, since that's the way
it will be operating.
I don't think there is anything to worry about as far as corrosion. The
old water heated 196 1V intake had a steel line screwed into the aluminum
intake cover. You just get a little corrosion over the years -- usually
takes 10-20 years to corrode/errode something like a nipple away. It will
eventually corrode, but the manufacturers at least think it's at an
acceptable rate. I don't think there's anything you can do about it
either. Maybe one of those electronic cathodic protection systems? In
principle they should protect EVERYTHING grounded to the car, as long as
you have a sacrificail anode (or is it cathode?) attached. We use those
for underground pipe protection, so in theory it should work on a car. I
don't know of anyone who's used one long term to ask though. I ran a quick
Google search and came up with this though:
http://www.corrosion-doctors.org/Car/carCP.htm. Will have to read!!
On November 20, 2005 Tom Jennings wrote:
> (STUPID G4 TRACKPAD)
>
> So I was stupid for putting an old, used heater core in so difficult
> a place. The lowest corner of the core has some crusty whitish
> corrosion; the rest looked good.
>
> I had vacuum-pump tested it; I even re-tested it before I extracted
> it. It held vacuum (15" or so) for >> 30 seconds, and still leaked.
> Oh well no test os foolproof.
>
> It never occurred to me to check for electrochemical corrosion
> before. So I did. All of my cars have been cast iron blocks with
> copper/brass radiators; you keep the juices fresh and electro
> corrosion is basically not an issue.
>
> But now I have an aluminum intake manifold, with hot coolant running
> through it. I assume that if everything is grounded the corrosion
> will be close to zero, but when I got the (used, junkyard) fold, the
> iron hose nipples had corroded into the manifold (since repaired of
> course). Millions of cars were made like this -- do they simply eat
> more brass than older American cars without aluminum in the system?
>
> So anyways. I few weeks back I flushed the system (mild cleanser),
> new 50/50 coolant, anti-rust/anti-corrosion additive, and a wetting
> additive. No cooling system problems.
>
> Tonight I got the car hot with the radiator cap off. Put a DVM from
> battery - to the juice in the radiator. Right after the thermostat
> opened, the voltage on the probe went up to 0.200 volts; after that
> the voltage never went higher than 0.100 - 0.140.
>
> I tried grounding the heater core, which floats since it sits in a
> plastic box. No effect.
>
> Should I be concerned?
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