HI Max,
I am one of those that has used JB Weld = for heads.  At last count, there were another 100,000 miles on the fix.   When I was looking into what to use, I called the = company and they said it would stand 500 degrees intermittantly. Hopefully there is = nothing in your engine, short of the exhaust, that gets to that temp. 
Mark Rokus
'87 GL Syncro = Westy
'87 GL Syncro
'86 Syncro (hanger Queen)
'81 Westy Aircooled
'82 Rabbit = Diesel
----- Original Message -----
From: Max = Wellhouse
To: vanagon@GERRY.VANAGON.COM
Sent: Sunday, June 10, 2001 = 2:15 AM
Subject: Re: '90 Vanagon: Hose = leaking antifreeze

Even the higher quality epxies won't = handle 200 degrees for long periods of time.  Get specifics from the = manufacturer of the resin as most packages don't have these numbers on them.  I = would think that JB weld would almost have to work since folks glue busted = crankcase pieces back together with it with seemingly good results, although = I've never tried it.  And if it's tolerating the sealing suface pit repairs = on heads, well, lwhat can I say??
 
DM&FS