Thanks John and Dennis. I have a spare used blue cap with me.
If I blow through it, the valve releases creation a honking sound as air
passes through.
Coolant transfer from coolant fill and expansion tanks seems normal but I'm
just guessing at that.
An archive post suggested that 'when under load' a head can lift off the
cylinders and allow a leak between cylinder and head. Since the engine has
been working harder and longer in higher ambient temps, a head May be
lifting.
After rebuilding the coolong system, I bled off air at rad a few times.
Air gap at expansion tank disappeared over time.
Yesterday I recalled that the compression test on engine when I first got
the van was marginal.
Engine has one AMC head. Power is ok though.
I Dont see a coolant path diagram for 86 and up wbx in Bentley but recall
that the upper connection at the coolant tank is a return feed.
I may pull the spark plugs and see what colour they are. I may have to go
home early anyway.
Possible root canal needed on a tooth.
Neil.

On Saturday, June 4, 2016, Dennis Haynes <d23haynes57@hotmail.com> wrote:

Sounds like you have loose or cracked heads, I would first test or have
> tested the pressure cap. New does not equal good with these things.
> Next would be to re-torque the heads and consider studs that are failing
> to hold torque, (stretching) which probably should be replaced.
>
> Dennis
>
>
>
> -----Original Message-----
> From: Vanagon Mailing List [mailto:vanagon@gerry.vanagon.com
> <javascript:;>] On Behalf Of Neil N
> Sent: Saturday, June 4, 2016 9:30 PM
> To: vanagon@GERRY.VANAGON.COM <javascript:;>
> Subject: Air bubbles in coolant 2.1 wbx
>
> The short version; after driving a while, I shut off the engine, heard a
> gurgling sound, saw bubbles passing into the top nipple at the coolant
> expansion tank. I'm concerned that a cylinder to head seal is failing.
>
>
>
>

--
Neil n

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