[VAC] Re: Aluminum Termination Cap

["Frank M. 'Mitch']

I just went through the process of replacing the dump valve on my '64
Ambassador. What I found was great confusion as to what fits and what
doesn't. It seems the original parts as supplied by Thetford no longer
exist. The good news is that Thetford still exists and has parts to change
the system to the newer type fittings.

The key problem I found was that the type and size fitting as originally
used has been changed slightly by a increase in diameter by approximately
3/8" A new cap from Thetford does not fit the old style Thetford fittings.
It almost fits, but does not lock on or seal securely. InlandRV of Corona
California has the parts in stock, including a coupler adapter ring to
modify the old dump valve coupling to accept the new style Thetford
fittings. This means you will have to replace the elbow coupling as well as
it will not fit the new Thetford fittings.

In the case of my '64 Ambassador, I was forced to replace the original
(brass & plastic) Thetford dump valve due to the seal retaining ring for
the brass gate valve slide being deteriorated to the point it would no
longer hold the gasket. I purchased a new Thetford dump valve from
InlandRV but could not get a new "Y" coupler for the grey water waste pipe.
I was forced to keep the original "Y"coupler which had the old style
Thetford coupler flange. The solution was to saw off the old flange and
epoxy a new style Thetford coupler adapter ring (purchased with the valve
from InlandRV) onto the end of the original "Y"coupler.

Now the caveat to all this is, the Thetford fittings, new or old are not
compatable with the Valterra and other readily available fittings. However,
Valterra makes an adapter to go from the new style Thetford fittings to the
Valterra syle fittings which includes most currently readily available
fittings at Camping World and most RV supply houses. I chose to stay with
the Thetford fittings as they are a stronger, better designed fitting and
more in keeping with the Vintage Airstream concept. However, once new
Thetford fittings are installed, by purchasing a $9.00 Thetford to Valterra
adapter ring (made by Valterra), you can use either as you wish.


Mitch Hill - WA1YKN / AFA1HN
64 AS Ambassador I'ntl
WBCCI #21960