I've seen the "sand" you describe a few times. More often I see redish-brown
mud as the form of "Sludge", and it's what I would define as the common
"sludge".
For both of these reasons, I suggest you flush the system 'from time to
time'. Once a year is great. Once every few years is fine. Just flush it
from time to time. Fresh coolant is good for the engine, it prevents
corosion and lubricates parts. So the more often you flush, the better, just
do it "from time to time".

-Craig
'85GL turned WESTY
BOSTIG in back
'87 SUNROOF Syncro

On Sat, Feb 12, 2011 at 11:11 PM, David White <sirgrumpsalot@gmail.com>wrote:

> 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
>