@Bill - I've blown through that pipe, it is not blocked.  In fact, I used
it to drain the extra coolant out of the bottle.  I wonder about it being
air tight though, although I've seen no leaks.

@Dennis - Thanks.  I've been tempted to build a cap tester just to confirm
my theory on that cap holding too much pressure.  I ended up replacing
bleeder valve assembly, radiator, and at least one hose after that had
happened.  The only other thing I can think of that may have caused the
pressure problems was a badly routed front heater bypass job (the heater
hose may have been pinched behind spare tire).

I have done the combustion gas sniffer test, and it came out ok.  I guess I
should have a compression and/or leakdown test done again and see if that
shows any signs.  As you alluded, I suspect it may only be failing when
driving/under load.

Any other ideas to confirm the issue before tearing the engine apart or
replacing... :/

Tom

On Sat, Apr 27, 2013 at 3:49 PM, Dennis Haynes <d23haynes57@hotmail.com>wrote:

> Once the system is bled enough to work it should never need bleeding again.
> Normal cycling (heating/cooling) will purge any remaining air out. Anytime
> it has to be bled or topped off between servicing is an indication
> something
> is wrong. From my experience denial never fixes anything. Multiple failed
> hoses are a symptom and I have yet to see a pressure cap fail to open at
> some point. Unexplained coolant loss is often the result of the coolant
> getting forced unseen while you are driving. This usually happens during
> extended highway drives or periods of extended load. The heads are being
> lifted off the cylinders or you have cracks and under these pressure
> conditions the combustion gases are getting into the cooling system. Most
> times the system can take this for some time and even bleed itself out but
> too much for too long things go wrong. The worst is when enough gas gets
> into the system and the water pump stops pumping. The gauge won't indicate
> the lack of flow until thermal cycling gets something to flow, usually
> steam. Coolant rising in the recovery tank with air space in the main
> pressure tank says head problem all over. Coolant blowing out and both
> tanks
> going empty could be a bad pressure cap not holding pressure at all.
>
> Dennis
>
>
> -----Original Message-----
> From: Vanagon Mailing List [mailto:vanagon@gerry.vanagon.com] On Behalf Of
> Tom Carchrae
> Sent: Saturday, April 27, 2013 11:21 AM
> To: vanagon@GERRY.VANAGON.COM
> Subject: coolant overflow fears and thoughts
>
> My van has been mostly dormant over the winter - although I have been
> driving it every week or two, partly for fun, partly to ward off angry
> lifter noises.  It seems mostly happy.
>
> But...
>
> I drove for 2 hours on the highway/city traffic yesterday.  Van was
> generally awesome.  I was trying to get somewhere in a hurry, so was
> perhaps
> a little heavy on the gas pedal - not that this helped too much, a racing
> van it is not (an 84 - 1.9L).  Temps were fine all during the day, (I have
> an aftermarket temp gauge, which was stuck at about 190oC for most of the
> trip)
>
> When I got home I noticed the overflow tank nearly, well, overflowing.  I
> thought, well, it is just hot, let it cool, then check it tomorrow.  When I
> checked the next day, the overflow level was the same (nearly overflowing
> out the tiny air hole in the top).  The pressurized expansion tank had
> perhaps an inch or so of air in the top of it.
>
> I have a theory, yet to be checked, that the overflow to expansion tank
> tube
> has a leak/crack in it.  I don't see any leaks, but I wonder if sends
> coolant down and, instead of drawing coolant back, it sucks air in
> somewhere.  Or, rather, that this is happening somewhere on the cooling
> system.  The pressure tank is holding pressure (it releases it when I
> unscrew it), so where else could this happen?
>
> Am I dreaming that a $5 hose could fix my problem?  I'll certainly try it
> as
> a solution.  Or is this a head gasket job.  I had a lot of scares last
> summer in that department (on a 4000km trip) with a few coolant pipe
> explosions - but these seemed resolved when I switched to a new pressure
> cap
> on the expansion tank.  decent mechanic in regina didn't think it was head
> gaskets because no overheating.
>
> I should note that before this trip I blew nearly $2k on a mechanic who put
> the previous new cap on it - sigh!
>
> So, I'll drain the overflow tank today, bleed the radiator (which I assume
> must need bleeding unless my engine is shrinking) and pour it back into the
> expansion tank.
>
> Also, how clean should your coolant look?  I've done a CO2 sniff test on
> it,
> but it still looks a bit filthy to me.  Granted, I did perform two coolant
> pipe operations where I 'captured and recycled' the coolant - as you would
> on the side of the road.
>
> So yeah, I guess it looks like I need to schedule some time to do my head
> gaskets.  Or new engine.  Or I just keep creeping around and shuffling
> fluid/bleeding air.
>
> What would you do?  Time is a bit scarce for me at the moment.  Never done
> a
> head gasket job - but I have some new fuel lines I'd like to install and
> why
> not take off a few more bolts and change the gaskets, huh?.. :)
>
> Thanks,
>
> Tom
>