I don't see why you don't just take it out and send it to a radiator shop.  That's what they do. It's not expensive, and they'll repair any holes that this process can uncover,  and then pressure test for leaks. 
Some things are best left to the professionals, and this is one of them.

Mike B.       
  ----- Original Message ----- 
  From: Janne Ruohom�ki 
  To: vanagon@GERRY.VANAGON.COM 
  Sent: Monday, April 05, 2010 5:08 AM
  Subject: Re: Archive not. Re: Radiator flush

  Sorry for not so exact answer but..

  Citric acid can probably eat some of the aluminum if solution is of
  very high concentration. That being said, I do not think that You
  would be able to do damage to Your radiator very easily with citric
  acid alone. It can etch the aluminum. Etced aluminum will look dark.
  Just etching does not damage the aluminum (well, it does but not
  significantly), but at that point You have already solution strong
  enough to change the composition of non-corroded aluminum. Different
  acids have different properties with metals, but generally oxidized
  metals You want to remove here are more actively reacting with acids
  than the healthy metal itself.

  The radiator should probably be cleaned with some cleaning detergent
  in order to allow citric acid to contact the inner surfaces of the
  radiator. Oil for example on the surface will prevent citric acid from
  doing the magic. Some commercial products meant for this probably have
  cleaning detergent already in addition to acid itself. I like my acid
  and soap separately.

  And do stay on mild acids when working with aluminum. With stronger
  acids You wont be able to find Your radiator anymore.

  On Mon, Apr 5, 2010 at 12:39 AM, Zolly <zolo@foxinternet.net> wrote:
  > Finally an answer. The only one. Thanks Doug. OK, what dilution ratio
  > shell I use? How good is it with the aluminum?
  > Zoltan
  >
  > ----- Original Message -----
  > From: "Doug" <vanagons@cox.net>
  > To: "Zolly" <zolo@FOXINTERNET.NET>
  > Cc: <vanagon@GERRY.VANAGON.COM>
  > Sent: Sunday, April 04, 2010 1:11 PM
  > Subject: Re: Archive not. Re: Radiator flush
  >
  >
  >> Zolts,
  >> Diluted Citric Acid soak (12-24 hrs), rinse, repeat if desired.
  >> Happy Holidays!
  >>
  >> Zolly wrote:
  >>>
  >>> If you go through, but don't, the archive postings, you will see that
  >>> none
  >>> of them has an answer. IMHO the archive is not useful. Especially if
  >>> you
  >>> go by the Subjet line. Because by using the Subject line, the discussion
  >>> always changes to all kind of topics that are not related to it. And
  >>> this
  >>> time is not different. That is why I can't spend days to go through the
  >>> archive postings to find a slightly related answer that is totally
  >>> useless
  >>> anyway.
  >>> But I know, there is a solution to it, if not any other way than the
  >>> one I
  >>> will invent.
  >>> Keep on looking for a better way.
  >>> Zoltan
  >>>
  >>> ----- Original Message -----
  >>> From: "Bob Stevens" <mtbiker62@GMAIL.COM>
  >>> To: <vanagon@GERRY.VANAGON.COM>
  >>> Sent: Sunday, April 04, 2010 9:17 AM
  >>> Subject: Re: Radiator flush
  >>>
  >>>
  >>>>
  >>>> http://gerry.vanagon.com/cgi-bin/wa.exe?S2=vanagon&L=vanagon&q=radiator+flush&s=radiator+flush&f=&a=January+2001&b=1+December+08
  >>>>
  >>>>
  >>>> On Sun, Apr 4, 2010 at 10:06 AM, Zoltan <thewestyman@gmail.com> wrote:
  >>>>
  >>>>> I don't remember seeing a posting about how to flush a radiator to get
  >>>>> out
  >>>>> all the deposits. And what kind of liquid to use to free the deposits
  >>>>> up.
  >>>>> I can hook up a separate pump with two different hoses to it, so only
  >>>>> the
  >>>>> radiator would be involved. Do I need a certain pressure to push
  >>>>> out the
  >>>>> dirt? Do I need to do it both direction?
  >>>>> Anyone know anything about this kind of work? Do I need a filter with
  >>>>> flush like that?
  >>>>> I have tried to hook up the garden hose, but other than the water going
  >>>>> through freely, I did not achive any positive result.
  >>>>> Maybe I have to soak it with some liquid inside for a day to lift the
  >>>>> deposits, then flush?
  >>>>> Zoltan
  >>>>>
  >>>
  >>>
  >>>
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