That's what it was on my vanagon. Blown head gasket or cracked head.
Check it out now. Don't wait for the worst to happen like I did.

Jim

On Tue, Aug 26, 2008 at 9:54 AM, John Reynolds <kayakjr@comcast.net> wrote:
> I had a coolant level sensor develop a split late last year, I replaced it and now with less than 1,000 miles since that time, the new sensor has split as well.  I was careful tightening it.
>
> Could there be some reason, like too much pressure in the system that could create this problem?
>
> This is an 86,  2.1 Vanagon
>
> John Reynolds
> LiMBO
>