Thread Tools Search this Thread Display Modes
Old 02-03-2004, 01:22 PM   #1
3 Rivet Member
Join Date: Oct 2003
Posts: 132
Images: 2
Repacing blackwater dump valve

I want to replace my Thetford blackwater dump valve because it is frozen in the closed position and I cannot unscrew the screws that hold its two pieces together. I tried the Screw-Out product from Sears but the rusted screws gave out. Drilling out the screws presents a bigger problem because of the heat produced and the subsequent melting of the valves plastic body around the screw holes.

As a side note, if you have a tail light assembly with rusted screws, use a drill to drill into the head of the screw and all of a sudden as the screw head heats up the plastic will begin to melt and the nasty old screw can be pulled out before the plastic cools and hardens once again!

I am thinking of cutting the pipe just above the valve and then replacing the frozen valve with a new valve. Is this a normal procedure?

If I cut the pipe, I think I will be left with a shorter than normal pipe on to which I need to cement the new valve. Would it be feasible to use a rubber sleeve that is made to join pipe sections to join an extension piece to which I cement the new valve?

Rick Alston is offline   Reply With Quote
Old 02-03-2004, 01:40 PM   #2
Rivet Master
87MH's Avatar
1978 31' Sovereign
Texas Airstream Harbor , Zavalla, in the Deep East Texas Piney Woods on Lake Sam Rayburn
Join Date: Jan 2003
Posts: 2,435
Images: 292
Can you cut em?


I replaced (rebuilt) my Thetford black water valve just this past weekend.

Just wondering;

1). Could you use a "Left Hand" (counterclockwise) drill bit?

2). How about a small Sawzall (Reciprocating Saw). I believe these can be rented, but they are not all that expensive to buy.
I think I have enough room to cut all four of the screws if I had to.

I ended up having to buy a whole valve ($45) because I could not find the "slide" separately.

I think that I would try to cut the four long screws, and back out the dutchmen with a vice-grip.


"Suck it up, spend the bucks, do it right the first time."

WBCCI # 1113
AirForums #1737

Trailer '78 31' Sovereign

Living Large at an Airstream Park on the Largest Lake Totally Contained in Texas
Texas Airstream Harbor, Inc.
87MH is offline   Reply With Quote
Old 02-03-2004, 01:58 PM   #3
3 Rivet Member
Join Date: Oct 2003
Posts: 132
Images: 2
Cutting the screw heads off may work


Your idea to saw off the screw heads is probably a good one. I've got to see how much working space exists in and around the pipes.

Of course, I might end up in the same situation as you and have to purchase the entire valve just to get the slide mechanism. If that is the case, perhaps I should just go ahead and cut off the valve and get it over with.

Thanks for you advice-I will let you know how things turn out.

Rick Alston is offline   Reply With Quote
Old 02-03-2004, 03:20 PM   #4
Rivet Master
Ken J's Avatar
1956 22' Flying Cloud
Durango , Colorado
Join Date: Sep 2002
Location: 1975 25' Tradewind
Posts: 3,331
Images: 14
I found the easiest thing to do is to cut both valves out and replace the whole thing. In my case (75 Tradewind) I could not easily replace just one valve.

So now I have new from the tanks to sewer connection. PVC is not that expensive....

Ken J.
Ken J is offline   Reply With Quote

Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off

Virginia Campgrounds

Reviews provided by

Our Communities

Our communities encompass many different hobbies and interests, but each one is built on friendly, intelligent membership.

» More about our Communities

Automotive Communities

Our Automotive communities encompass many different makes and models. From U.S. domestics to European Saloons.

» More about our Automotive Communities

Marine Communities

Our Marine websites focus on Cruising and Sailing Vessels, including forums and the largest cruising Wiki project on the web today.

» More about our Marine Communities

Copyright 2002-2015 Social Knowledge, LLC All Rights Reserved.

All times are GMT -6. The time now is 09:12 AM.

Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2016, Jelsoft Enterprises Ltd.

Airstream is a registered trademark of Airstream Inc. All rights reserved. Airstream trademark used under license to Social Knowledge LLC.