Date: Wed, 17 Feb 2016 11:03:14 -0800
Reply-To: Stuart MacMillan <stuartmacm@GMAIL.COM>
Sender: Vanagon Mailing List <vanagon@gerry.vanagon.com>
From: Stuart MacMillan <stuartmacm@GMAIL.COM>
Subject: Re: Expansion tank under pressure when cold?
In-Reply-To: <CAE_mVa2Q1vEdd44zSmbvordB1UqqbG-vW7cnaGJ3p99aPn60Rg@mail.gmail.com>
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Bentley says apply 14.5 psi for leak testing (p. 19.17), and cap opens at 13 to 17 psi (p. 19.18). I use my Motive Products pressure brake bleeder, but anything with a gauge will work, just connect a hose to the cap. Put a large piece of clean cardboard under the engine and look for drips immediately as well as overnight (system should hold pressure for several hours). If you are smelling coolant, it could be the rubber head gaskets leaking, but that would not lead to a pressurized tank.
An emissions sniffer can detect combustion gasses in the cooling system, but for that to work there has to be considerable air space in the pressure tank, and the probe inserted quickly after opening the cap. Not so easy, and the shop is not going to want to contaminate their probe with coolant.
Also, it's worth taking the cover off the rear heater and pulling out the core. I'll bet it's leaking if it's original.
You’ve got air in the system, hopefully it's not from combustion gasses.
Stuart
-----Original Message-----
From: Vanagon Mailing List [mailto:vanagon@gerry.vanagon.com] On Behalf Of Michael McSwain
Sent: Wednesday, February 17, 2016 10:14 AM
To: vanagon@GERRY.VANAGON.COM
Subject: Re: Expansion tank under pressure when cold?
Any easy way to test for combustion gasses getting into the coolant?
Loose or cracked heads would produce a leak or weeping from the head area I assume?
Radiator should be easy enough to check for leaks, but heater core not so much.
I've tried taking the expansion tank cap off after letting the van sit overnight and it still overflows when removed. Where I park it is slightly inclined with the front end up, but not much. I'll try parking it front down tonight and try removing it again tomorrow morning.
Is applying 10 or so psi of pressure to the expansion tank and looking for pressure drop and leaks a bad idea?
On Wed, Feb 17, 2016 at 1:01 PM, Dan N <dn92610@gmail.com> wrote:
> I think it depends on how long you let the engine rest after you shut
> it down. There always some residual pressure in the cooling system and
> it will come near zero if you wait long enough... I let it sit
> overnight. My mechanic revs the engine up to bring the level down, add
> the coolant and put on the cap presto..
>
--
m.