Just make sure the two sealing surfaces are clean and free of any debris.
You could coat the o-ring with some silicone grease.

-Mark

On Thu, Oct 14, 2021 at 6:49 AM Eric Caron <ericcaron96@comcast.net> wrote:

> Yes,
>
> I have the same metal rear heater valve.  Probably VC as I worked mainly
> with them until they merged.
>
> But I’m leaking between the metal valve and the heater core.
>
> So, I’m just wondering if there is something I’m missing in the change of
> O ring process.
>
> Eric Caron
>
>
> > On Oct 13, 2021, at 11:09 PM, John Rodgers <jrodgers113@GMAIL.COM>
> wrote:
> >
> > Ok, thanks. I bought a whole new METAL valve from Van Cafe.Came with
> seal.
> > Have never had anymore troubles with leaks. Sweet!
> >
> > On Wed, Oct 13, 2021 at 8:16 PM Eric Caron <ericcaron96@comcast.net>
> wrote:
> >
> >> Yes,
> >>
> >> Rear heater valve, connection to the rear heater core.
> >>
> >> Eric
> >>
> >>
> >> On Oct 13, 2021, at 5:13 PM, John Rodgers <jrodgers113@gmail.com>
> wrote:
> >>
> >> Is this the one in the rear heater?
> >>
> >> On Wed, Oct 13, 2021 at 3:48 PM Eric Caron <ericcaron96@comcast.net>
> >> wrote:
> >>
> >>> Hi Folks,
> >>>
> >>> It took about two weeks but I received my O ring from GW.  I’ve
> replaced
> >>> it before and it lasted about 7 years.  Low usage and miles though.
> >>>
> >>> Are there any tricks to replacing it that makes it work better?
> >>> I clamped off both hoses.
> >>>
> >>> I remember simply wiping down the surfaces, pulling the old O ring
> gasket
> >>> and putting in the new one, and bolting together.   I’m just wondering
> why
> >>> it lasted only about 5,000 miles and 7 years.
> >>>
> >>> eRic
> >>>
> >>
> >>
>