Blown head gasket could figure in there too. 

Jim

On Nov 29, 2011, at 12:47 AM, Karl Wolz <wolzphoto@Q.COM> wrote:

> You can use an exhaust sniffer (or your local mechanic can) to detect the
> presence of exhaust gasses in your coolant tanks.  If so, almost certainly a
> cracked head.
> 
> Karl Wolz
> 
> 
> 
> |-----Original Message-----
> |From: Vanagon Mailing List [mailto:vanagon@gerry.vanagon.com]
> |On Behalf Of Evan Mac Donald
> |Sent: Monday, November 28, 2011 8:22 PM
> |To: vanagon@GERRY.VANAGON.COM
> |Subject: <No Subject>
> |
> |Ok list, I need some help.
> |
> |I need somebody to tell me the symptoms my poor '85 1.9 WBXer 
> |is suffering from are not from a cracked head. Lie to me if you must.
> |
> |So, to explain. My van (Butternut) has always self-bled her 
> |cooling system very quickly, and easily. No fights, no real 
> |fussing, just a couple of top-offs after a couple of careful 
> |hot-and-cold cycles, and Viola! Done. This is from several 
> |waterpumps, hose replacements, damage repairs, etc. Always 
> |bleeds fast, after the damage is gone.
> |
> |The last run we made in beasty was at the end of September, to 
> |Busses by the Beach Bus Boo, in western Michigan. Lots o' fun. 
> |I live in eastern Michigan, so the trip is only about 180 
> |miles. No big deal. Done the trip LOTS of times, and in much 
> |worse weather.
> |
> |This time, about 5 miles from being home, the heater stops 
> |working, and the temp gage maxes out. Quickly. And the coolant 
> |level light blinks. The weather at the time was about mid 
> |50's, in °F. UH-oh. not good. I stop, and the light stops 
> |blinking, and the gage returns to normal. Huh? Check the 
> |tanks, and both are full of air. Now, my reservoir tank never 
> |has bubbles, after bleeding. So , I fill the tanks, and start 
> |home again. Cycle repeats. First I have heat, then none, and 
> |the gage does its dance. It is the old style gage, that maxes 
> |out the temp needle, if the low-level alert light comes on.
> |
> |I have tried several times, over the intervening time, to get 
> |the bubbles to go away, and my heat to return. I completely 
> |emptied and refilled the entire system, with a pressure flush 
> |in between. I even unhooked the belt from the water pump, and 
> |spun it with an angle grinder, to get things moving around, 
> |without actually running the engine, and risking further 
> |damage. This will really only clear the heater cicuit, but 
> |that is a big section of the problem, all on its own. No joy. 
> |
> |
> |My thought is that I have cracked a head, into a coolant 
> |passage. I do not want to do a head if that's not whats wrong, 
> |but I do not see any other solutions for this problem.
> |
> |My question is: are there any other likely causes of this? Or 
> |am I going to have to replace a head?
> |
> |TIA, and I hope everybody is over their tryptophan overdose...
> | Evan Mac Donald 
> |
> |
> |"...in the absence of facts, myth rushes in, the kudzu of history."
> |-Stacy Schiff
> |-----
> |No virus found in this message.
> |Checked by AVG - www.avg.com
> |Version: 2012.0.1873 / Virus Database: 2101/4645 - Release 
> |Date: 11/28/11