I've seen all kinds of sludged up waterboxer engines or whatever..
As long as the essential failure point is repaired properly ..
and there are no other little near-failures in the rest of the van ..
quite some parts in total there of course , 'usually' they will do well with
a good cleaning out and a good batch of fresh coolant and addtives.

generally it's not a good idea to mix anti-freeze types.

and it depends on the condition of the rest of the engine ..
how good the bottom end is, now good oil pressure is, total miles etc.

and I always have a valve job done on the heads at the same time as doing
head gaskets.

if the engine is bascially solid, often a good cooling system clean-out and
freshen up ..
vavle job and head gaskets, and make sure the t-stat makes it run up to
temp, radiator fan works...heaters work well, etc.
usually they can be just fine after good work on those things.

Scott
www.turbovans.com

----- Original Message -----
From: "David White" <sirgrumpsalot@GMAIL.COM>
To: <vanagon@GERRY.VANAGON.COM>
Sent: Saturday, February 12, 2011 8:11 PM
Subject: Coolant sludge?

> Can anyone describe what coolant sludge would look like? I had both
> head gaskets fail at the same time and I've pulled the engine and
> removed the heads. I notice that there about a quarter inch of "sand"
> in the bottom of the coolant reservoir. Is this the famed sludge? This
> 84 1.9L had a mixture of the green Sierra and the Zerex G-05 phosphate
> free stuff, probably about 50/50. The heads look like they have been
> leaking for awhile, not alot of pitting under the gaskets though, just
> gasket failure. Should this engine now be a boat anchor or can it be
> saved?
>
> David in Idaho