Paul,

I had the same situation just this week.  I had blown two hoses in two days.

My mechanic used the exhaust gas analyzer to find hydrocarbons in the
cooling system.  He then did a cylinder leakage test, blowing air into each
cylinder, till he found the one that passed air into the cooling system.
This told us where to look for the problem once the head was off.

I don't know why a radiator shop would have these capabilities, but any
mechanical shop that does emissions analysis should be able to help you.

Karl Wolz

----- Original Message -----
From: "Paul Cavanaugh" <phonyexpress@IWAYNET.NET>
To: <vanagon@GERRY.VANAGON.COM>
Sent: Friday, June 29, 2001 3:04 PM
Subject: Re: 4th heater core burst in 1 year!

> Thanks Rico!
>
> I replaced the expansion tank cap today, hoping to avoid future
> trouble until I can get this diagnosed. I am getting a lot of folks
> suggesting head or head gasket leakage. Your explanation seems very
> likely; a big thanks for the idea to take it to A RADIATOR SHOP!
> Never thought anyone can test for combustion gassis in the cooling
> system!
>
> This is my first week on Vanagon.com and I really appreciate the help!
>
> Sincerely,
> Paul Cavanaugh
> Columbus, OH
>
>
> >This overpressurization of the cooling system is likely caused by a
failure
> >of the sealing ring at the top of the cylinder or a leak in the cylinder
> >head.  This would allow combustion gasses to enter the cooling system and
> >destroy the components you mention.  Take the van to a competent radiator
> >shop and have them test the coolant for the presence of combustion gasses
in
> >the cooling system.  This happened on my 84 and it ruptured the rear
heater
> >core and one of the heater hoses.
> >
> >Rico Dagastino
> >Munford, TN
>
> --
> '90 Vanagon (180k)
> '84 Vanagon (217k)
> '78 Microbus (175k)
>