you never get it all out anyway.
I'd suggest drain what you can...........refill with your preferred
mix........
that'll get you say 40 % new coolant.
Drive that a few days, and do it again.
that'll get you up to ..........70 % 'all new'.
that's one way.
I wouldn't go messing with bolts that might break off.
And.............I really don't think many vanagon owners, or shops, that are
changing vanagon coolant go to the trouble of getting those push rod tube
covers off to get at the little drain plugs.
After removing a main hose from the left side of the engine, you could raise
the front of the van, and remove the bleed valve screw , to coolant will
flow from the radiator toward the engine and out. That'll get more out.  Be
creative.

there's no real opportunity to do this in your case.............but one of
my many tricks, in this case for draining a block where a head as been
removed...........I put a rag into the coolant, and let the rag hang over
the side of the block. Overnight this will remove the coolant in the block
by capillary action.

Scott
----- Original Message -----
From: "Jeff Hartman" <jeffreyleehartman@GMAIL.COM>
To: <vanagon@GERRY.VANAGON.COM>
Sent: Friday, October 17, 2008 8:48 PM
Subject: Another way to drain coolant

> Hi, I tried to send this message a few days ago, but didn't get a
> response.
> That is rare with this helpful group, so I thought I would try again.
>
> In attempting my first complete replacement of coolant for my 2.1 86
> vanagon, my Bentley points to the drain plugs between the pushrod tubes as
> the proper location to drain.  These plugs are accessible after removing
> some type of shield or sheet metal covers.  Two out of four hex head cap
> screws on each side are badly rusted.  The hex nuts are so rusted there,
> that I bypassed replacing that part of the exhaust system a few years ago.
> Is there another way to drain the coolant?
>
> Thanks, Jeff
> Jeff Hartman
> Juneau, AK
> 86 vanagon 2.1