[AT] Old Antifreeze

[Dave Ernst]

Question for the Guru's.
I've been told that several years ago Prestone had a problem with their 
anitfreeze "crystalizing and gumming up".
I had never witnessed it before until I was forced to tear into this John 
Deere I'm working on because no. 1 cylinder had no compression. I am told 
this tractor last ran 7 years ago. The head had the valves done and a new 
gasket installed without any coating such as Copper Coat which I use 
religiously.
Anyway the gasket seeped into the intake and I couldn't believe the 
coagulated mess. Like semi-dried up jello. The ports looked alike a clogged 
galvanized water pipe and were virtually closed shut with this junk. The 
radiator is plugged with this stuff and what suprised me is I drained almost 
5 gallons of liquid, but it was almost clear.
The owner said he used new Prestone in it.
Anyone else heard or have seen this?
A picture of the valve and seat is at
http://albums.photo.epson.com/j/AlbumIndex?u=3009545&a=31641177&f=

Dave