I have the same problem. The leak seems to be between the core and the
plastic housing. My best guess is that the 2 seals (rubber O  rings) between
the plastic and core need replacing. The Bus Depot has them on back order.

The question is how do you separate the side plastic cover from the heater
core? It looks it is crimped on

For the time being I removed the heater core. You can plug the rubber hoses
with a bolt and put some clamps on it, or make a U shaped bypass out of
copper pipe (double clamp it), or remove the rubber hoses in its entirely.
This is what I did since I was doing a complete flush anyway. I replaced the
T fitting under the Westfalia with a straight one.

Hans Brouwer
86 Westfalia
Cumberland, Onatrio

Drew Bedford wrote:

> As I pulled out the back seat of my Westy I discovered a long-hidden
> coolant leak. The slow leak is coming from what I believe to be the
> control valve for the rear heater. I didn't even know there was one.
> Can't find a picture of this part in my Bentley, so I'm appealing to the
> list to confirm my suspicions. The leak seems to be coming from behind
> the control lever (aluminum) itself. Is this something that is fixable
> with a new seal, or is this part notorious for leaking and needs to be
> replaced in total?
>
> TIA,
> Drew Bedford
> 83.5 Westy
> Park City, Utah