Jim: I guess I got lucky - no coolant drips.  But you make a good point
about what a crazy system that is and why it is prone to failure.

Scott: I have tried a few blue caps.  I need to make a cap tester and/or
run the van with a pressure gauge on the expansion tank when the van is
running.  (Test # 2 from
http://web.archive.org/web/20050309065156/http://www.bostonengine.com/articles/waterboxes.html
).
 I've previously done a test for exhaust gasses, but no CO2 detected.  I
have wanted to plumb a pressure gauge into the cooling system for some time
now - I am not brave (stupid?) enough to put it in on the dash, but I am
definitely going to rig up a temporary one to the expansion tank.

When I bought the van, I took it to a mechanic, who said, "hey your cap is
bad, we changed it" - and he did some work on my heads, what I am not sure
although it involved valve adjustment to fix low compression.  After this,
the cooling system started blowing up here and there and nearly $2k later I
was broke and annoyed and have not returned to that mechanic.  I then said
screw this and have most of the work on the van myself since.  I drove it
across western Canada and the cooling system blew up twice more on me -
after the first time, I changed the cap to another spare I had bought.  The
second time was due to air in the radiator and a giant traffic jam (a
massive mud slide on Hwy 1) and the van actually overheated (went to ~220oC
and it was full of water) and the coolant sensor popped off - its
whereabouts are still unknown.  Both times the van was pretty heat soaked
and running at slow speeds - I learned a lesson there.

So, yeah, it is probably due.  And I actually enjoy working on it, so it's
not all bad.

Btw, are there any engine stands and hoists that are specifically designed
for working inside your van?  :)

Tom

On Wed, Sep 4, 2013 at 6:25 PM, Scott Daniel <scottdaniel@turbovans.com>wrote:

> PS to my last post.
> Make sure it's not the blue pressure cap. Try another one. They are
> notoriously flakey sometimes.
>
>
>
> On 9/4/2013 4:37 PM, Jim Felder wrote:
>
>> The head bolts and the heads do two things simultaneously, and do only one
>> of them very well.
>>
>> They hold the aluminum ring that serves as a true head gasket; that is,
>> that gasket confines the compression gases to within the cylinder, without
>> leaking it to the outside world. The other thing that is going on is that
>> the head also squeezes a rubber gasket between the head and the water
>> jacket on the block. This is imprecise. Normally, the compression head
>> gaskets do not fail very often. That is not true of the outer water gasket
>> which is held in place by the same head bolts. Think of it s a circle
>> (actually two circles on each side) of metal, with very precise clamping
>> pressure to hold in the combustion gasses, surrounded by a rubber gasket
>> which deteriorates, holding in the coolant.
>>
>> Guess which is going to go first?
>>
>> Yep, the rubber. If your head bolts are tight enough to contain the
>> combustion gasses, but you are leaking water, you are not going to affect
>> the rubber more than a thousandths or two by tightening the already tight
>> bolts holding the compression gaskets in place. If you are leaking
>> coolant,
>> it is because your rubber gaskets have a breech somewhere, not because
>> there is not enough pressure on them.
>>
>> It always makes me feel better to go through the procedure or tightening
>> the bolts as you suggest, but, in the end, you will have to pull the heads
>> and replace the outer rubber gaskets.
>>
>> Jim
>>
>>
>> On Wed, Sep 4, 2013 at 11:54 AM, Tom Carchrae <tom@carchrae.net> wrote:
>>
>>  I've put this off long enough.  I got a few trips from my van this
>>> summer,
>>> but on the last day I drove it, it backed up the coolant in the reservoir
>>> (behind licence plate) three times in one day.  I would pull over when
>>> the
>>> blinking low-coolant light turned on, drain the coolant out into a
>>> bottle,
>>> start the vehicle, open the hot pressurized tank, and pour the coolant
>>> back
>>> where it belonged.
>>>
>>> Yesterday I took the valve covers off and used a torque wrench to inspect
>>> the tightness of the nuts on the heads - well, all the easy to get to
>>> nuts
>>> (so all but the two behind the air intake - I have only removed the air
>>> filter box so far).
>>>
>>> I have only done one side so far, but I found one of the bolts in the
>>> centre of the head to be slightly under spec (37lb).  I recall Dennis
>>> Hayes
>>> saying (email below) that this managed to solve head gasket symptoms 50%
>>> of
>>> the time if done soon enough.  I doubt I have been soon enough, but how
>>> does one tell.
>>>
>>> I am prepared to do the head removal but boy would I be happy if it was
>>> as
>>> simple as tightening some nuts.  Would I be overly hopeful to think that
>>> this minimal nut tightening this late would save me having to remove the
>>> heads?
>>>
>>> Tom
>>>
>>> 84 Vanagon
>>>
>>>
>>>
>>>
>>> On Thu, May 9, 2013 at 2:19 PM, Dennis Haynes <d23haynes57@hotmail.com>
>>>   wrote:
>>>
>>>  One problem with relying on the sniffer tests is that they are looking
>>>>
>>> for
>>>
>>>> un-burned hydrocarbons. In order for this to work in addition to the
>>>> leak
>>>> you also need a combustion failure in the leaking cylinder. While
>>>> cracked
>>>> or
>>>> loose heads may also cause a combustion issue you are in deep trouble by
>>>> the
>>>> point the sniffer tests pick it up. Keep in mind if those gasses can get
>>>> out
>>>> in some cases coolant can get into the cylinders. Antifreeze into the
>>>> cylinders and then into the oil can cause some real damage. Long before
>>>> antifreeze in the oil is visible the stuff becomes extremely corrosive
>>>>
>>> and
>>>
>>>> can quickly destroy bearings along with crank and cam surfaces. It can
>>>>
>>> also
>>>
>>>> destroy pistons by blowing out the tops and destroying the ring lands.
>>>>
>>>> If the engine has ever been overheated, (even before a rebuild) or has
>>>>
>>> had
>>>
>>>> the heads off for any reason loose heads can be the cause. I probably
>>>>
>>> have
>>>
>>>> a
>>>> better than 50-50 success rate in fixing these issues just be retourqing
>>>> the
>>>> heads if the problem has not been left so long that the head seals
>>>>
>>> (inners)
>>>
>>>> or the tops of the cylinders have burned or pitted away.
>>>>
>>>> Dennis
>>>>
>>>>