​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.