Originally Posted by roger66ogden
The crack is on the top of the tank where the inlet pipe goes into the tank. There's a pipe strap that is attached to the cross member with self tapping screws and it is drawn down so tight that the pipe is bowed.
Yup! There has to be a cause... You have to fix the cause an then repair. While I'm away from my main PC with all my pics on it, it dawned on me, I have the camera with me and the pics are still on it.
These may help go with my words above. This is on my friends 2005 T1950. This floor plan has a unique left rear jogged frame rail that can allow that corner of the camper to flex. The grey water tank pipe is rigid to the camper frame. High towing mileage and I feel this setup is what created the issue.
Here is the setup starting at the tank.
The first hard pipe strap at the discharge of the tank
The tie in with 2nd hard strap to the dump valve area.
The as found 3rd repair leaking. The good news they used the ABS repair method so the plastic was no contaminated with foreign materials. I could grind it away and back to original ABS with the crack still there.
You can see the crack on the left side of the pic, there was a hair line split at the 6:00 location too. This is after grinding out the older repair and going deeper into the tank wall, but not breaking through.
Now to the fiberglass screen reinforcement. Screen blank over the top of a 1 1/2 to 1 1/2" Fernco fitting.
Slit the screen to fit over the pipe. Make a cross cut 2 ways 90 deg to each other the ID of the Fernco
Now to cut the pipe at the tank.
Pipe/crack ground out, acetone cleaned, ready to start ABS repair.
Screen test fit and slit corners to allow screen to flex under tank
Slit corners allows bottom flaps to fold under tank
Here is the first ABS coat. You can see the screen embedded. As it cures, the finish gets smoother as it slowly all melts together around the screen.
After 24 hours, repeated a second coat with screen and the 3rd coat, 24 hours later, a plain 3r coat no screen. Sorry no final close up of the 3rd coat, it came out good.
Now the pipe Fernco connections and new pipe hanger to flex in the correct direction to help mitigate stress into the tank pipe connection.
Two Fernco's strategically placed with a flex clamp.
Your setup will be a little different, but figured the pics will give you something to build on.
Hope this helps.
PS. Please post what you came up with, this pipe stress crack problem may be larger then we think. We do not have many posts on pipe stress cracking. Most times the whole tank dump fitting gets broke off in a crash/pothole etc. event. The repair can be similar, the cause is different.