I have the same problem. I tried tightening the valve bolts but the leak is
still there (although it's now much less). I'm going to try removing the
heater valve, disassembling it and reassembling it with some sealant. Hope
it works.

rp
'88 GL Camper

----------
>From: ERIC ZENO <emz@pgh.nauticom.net>
To: Multiple recipients of list <vanagon@lenti.med.umn.edu>
Subject: Re: Coolant under rear bench carpet
Date: Saturday, January 04, 1997 11:23 PM

Check the connection between the valve and the heat it self. Start
the engine, let it warm up, (under pressure) then put side to side,
on the hose leading to the valve and look for leaks!
  
                 Eric Zeno   <emz@nauticom.net>
                 86 VW-4x4
                 86 GL  For Sale (Pgh. PA)
                 72 240Z    1936 Chrysler

On Sat, 4 Jan 1997, Victor Wong wrote:

> HELP!  I pulled the never-used seat belts up from underneath the rear 
> bench seat of my '88 GL today, and was horrified to find them wet with 
> coolant.  I imagine there must be some kind of leak from the rear heat 
> exchanger.  I seem to remember a thread along these lines a while ago, 
> but I'm afraid I might not be able to find it in the archives.  Can 
> someone shed some light on what needs to be done?
>