I was mostly concerned about how to get a new dump valve in place with seals intact between two immovable objects until I tried to remove the faulty one, which I did not succeed. After removing the 4 bolts, the valve will spin, but the amount of force I applied to unseat it with no outward movement made me stop and ask for help. I've watched YouTube videos that show one or both sides of the valve to have flexibility in the plumbing, but for me, absolutely zero flex. The plumbing on either side of the valve is not moving anywhere. Any suggestions how to remove the valve and get the new one installed without seal issues?

You will need to pry lightly on the fixed plumbing pipes.To install a thin piece of sheet metal flashing material on each side of valve to slide it in. When in place slide sheet metal out. Coat metal with dish soap will make it easier to slide out.What is all the gunk around inlet to the tank?

Try looking further down the line to see if there is any brackets you can remove to give it some play.

All that gunk is Plasti-melt which was supposed to fix a hairline crack in that area that was leaking. What you're seeing is about 8 coats of it, which by the way, did not fix the leak. I used some epoxy over the Plasti-melt that ultimately fixed the leak.

24fb freedom wrote:Try looking further down the line to see if there is any brackets you can remove to give it some play.X2, also it might help to have someone helping you with this project. I have found on some systems two people make it easier to install. JMO

use a ratchet strap to lightly pull at the elbow to give enough clearance

Dump valve replacement gone bad | Good Sam Community

rhagfo
Explorer III
Aug 15, 2015
ol Bombero-JC wrote:
24fb freedom wrote:
Try looking further down the line to see if there is any brackets you can remove to give it some play.

Been there, done that - loosen brackets to allow movement.

Might be time to re-engineer the entire tank & plumbing set-up.

Whether you drop the tank or not.....
A "standard" (not remote) valve closer to the final exit section
of 3" pipe is great "old school" - easy to access for anything!..:C

.

X2!

I have a leaky grey water valve, the drains on my grey and black tank face each other and connect to a "Y" between the tanks.
I used the I got one of the exit valves, and for now that works, but I really want to correct the valve issue and replace it.
Halmfamily
Explorer
Aug 16, 2015
therink wrote:
If it were me and I couldn't loosen the drain pipe enough to get flex to unseat the valve, I would likely cut the 3" drain pipe with a saw and reconnect using a 3" fernco connector.
The use of aluminum flashing between the valve seats to remove and reinstall is good advice.

This is how I replaced my 3" valve. Much easier to do if you need access in the future, loosen the two clamps and pull the pipe apart.
enblethen
Nomad
Aug 16, 2015
OP will still have his leak at the tank. It would better oin the long run to have a professional remove all the gunk, fix the inlet Grommet with one of the tank grommets and replace the valve.
magic43
Explorer
Aug 16, 2015
I second the motion about adding a 3" Fernco fitting. It makes future valve work a snap.
Carl_n_Susan
Nomad II
Aug 16, 2015
Halmfamily wrote:
therink wrote:
If it were me and I couldn't loosen the drain pipe enough to get flex to unseat the valve, I would likely cut the 3" drain pipe with a saw and reconnect using a 3" fernco connector.
The use of aluminum flashing between the valve seats to remove and reinstall is good advice.

This is how I replaced my 3" valve. Much easier to do if you need access in the future, loosen the two clamps and pull the pipe apart.

This is what I did too. The other advantage is you can control the tightness of the valve connection (i.e. the pressure from the 3" pipe which squeezes the valve housing) to ensure it isn't difficult to open.
Cummins12V98
Explorer III
Aug 16, 2015
" I would likely cut the 3" drain pipe with a saw and reconnect using a 3" fernco connector"

EXACTLY!

I would NOT slide metal between the parts you could scratch the mating surfaces and cause a sealing problem with the new valve.

CUT THE PIPE!
3oaks
Explorer
Aug 16, 2015
In mielock's case, looking at the picture, there doesn't appear to be enough room to install a 3" Fernco coupling. The length of the existing 3" pipe is too short between the bell ends of flanged fitting for the one side of the knife valve and the next pipe fitting.
mielock
Explorer
Aug 16, 2015
Thanks for all the replies, which is much appreciated. As a result of the suggestions, I've determined that I can cut a 3" pipe that tees into the main outlet on the opposite side. It will be about 2' of loose pipe to handle, but at least I know it'll work. Thanks again for all who chimed in.
Dave_H_M
Explorer II
Aug 16, 2015
But I am thinking that maybe downstream of that fitting shown there would be room to install the Fernco coupling. OOPS me and op were at it sat the same time.
ranchertx
Explorer
Aug 19, 2015
Something that works really good for cracks in pipes is Gorilla Tape. Clean it good and rough it up a little with sandpaper. It will last for a long time until you can replace the cracked pipe.