Hi Mark,

Yes,

        I’ve posted about this same issue recently.

First, I noticed a leak started for no apparent reason on a low use rear core.  I had replaced the valve some time ago with the GW metal one. 

I replaced the O ring but it still leaked.  I then purchased a new rear heater core and when replacing I noticed the same Bowed problem.  I could feel a gap in the middle and when I took off the core and inspected it was now in a permanent bow,not flat. .

I put in another new O ring with the new core and it leaked less but still misted.

I then took it apart and had an experienced VW friend re assemble.  I used another new O ring.  It seemed a better but after running the van for a short time the mist slimy feel around the edge came back. 

So, I’ve still not completely solved the problem.

I really wish the dealers would come up with a better rear core.  It is nice that this one is cheap but no fun to keep replacing every few years and even then it often doesn’t work. 
The O ring also seems either of poor quality or design, or both.

I like having the rear heater but I’m beginning to think about just connecting the hoses and removing the rear heater and enjoying some extra space.  It isn’t what I want but until a better solution is available it may be my current solution.
Anyone out there with a solution for us?

Eric Caron 
85 GL Auto 

> On Jan 18, 2022, at 9:13 AM, Mark McCulley <markmcculley@GMAIL.COM> wrote:
> 
> I just replaced a leaky rear heater core and am having an issue with the
> flange on the new core sealing to the metal GoWesty valve that I've had for
> several years. I did obtain and use a new o-ring from GW. It seems that the
> new o-ring isn't compressing sufficiently--the plastic flange on the heater
> core bows in the middle when I cinch down the two bolts that secure it to
> the valve.
> 
> Has anyone else encountered this problem?
> 
> -Mark
> '87 Westy