Grey water slow draining issues

[M&EM]

Since new, our Dolphin has had very poor grey water plumbing either by design or installation.
Sometimes water will not completely drain even when level to slightly in favor of better drainage.
It often takes too long at dump stations to completely drain grey water. Given enough time the tank will eventually drain completely. Perris factory service has looked at this several times during and after warrantee but system just doesn't want to drain fast. I even had temporarily added a vent at the curb side of the grey tank. This did not seem to help.
Is this a common occurence with the Dolphin body type? Has anyone found a fix for it.

I suspect a pipe hole cutout may be trapped in the tank and randomly blocking the drain as sometimes the tank will drain with a lot more force.

Marty

[M&EM]

Since new, our Dolphin has had very poor grey water plumbing either by design or installation.
Sometimes water will not completely drain even when level to slightly in favor of better drainage.
It often takes too long at dump stations to completely drain grey water. Given enough time the tank will eventually drain completely. Perris factory service has looked at this several times during and after warrantee but system just doesn't want to drain fast. I even had temporarily added a vent at the curb side of the grey tank. This did not seem to help.
Is this a common occurence with the Dolphin body type? Has anyone found a fix for it.

I suspect a pipe hole cutout may be trapped in the tank and randomly blocking the drain as sometimes the tank will drain with a lot more force.

Marty

[Fred and Bonnie]

Marty, our '05 gray tank has always drained slower than the black tank, I always attributed it to the smaller size of the plumbing. I would be more concened if it didn't drain.

Fred

[Jestme13]

I believe even with the smaller pipe diameter it would drain off rather quickly. I think you may have something there Marty with the cut out rolling around in the tank, or anything else those knuckle heads coulda dropped in there! It very well could be blocking yer outlet. The only way I can think to check it short of pulling the tank is, find a plumber or a chimminy repairman that has a closed circuit TV system for pipes. He can slid it up yer grey discharge pipe and have a first hand look into, and around the tank. Sounds goofy, but it works. Good luck.

[Bill Davis]

Pull off the black cover plate in the sewage compartment and notice how shallow the tank is. It's wide, but not deep. Not much pressure from above to force the liquids out.I was going to install an aftermarket tank level sensing unit, but the difference between highest sensor and lowest sensor was only a couple of inches. National does not recommend them for that reason. Per Perris repair facility.

[M&EM]

Thanks for responses.

Last motor home had same grey water drain pipe size and flowed quite freely. This one doesn't flow very well even from the fullest tank levels.

NRV was willing to add an additional vent thinking that was the problem even after warrantee was over. I refused it since it seemed like too much

major work and too many things to mess up in the process and not enough evidence that was the problem.

Yes, I have had side black panels off and thought about adding some slope to the long flat tank. Too difficult!

I added 2 spray heads near the level sensors similar to those used in the black tank for flushing. These seem to keep the sensors working correctly.

I do have a tiny video camera that could possibly fit in one of those openings. So I may try that "goofy" idea Steve. The thought of a hole cut out now seems to be the only explanation for the observed drainage variations I see. Not sure how I would get it out if there was a cut out in there.

[w7co]

I have a 99 Tropical and it also has a smaller discharge pipe and a slower rate of discharge. I always figured this is the way it was.

[ronboc]

I had a SOB (some-other-brand) that did it too. Sometimes slow but sometimes a lot faster. Just lived with it til I tried to sell it, and then wouldn't ya know - it stopped up almost 100% when i was showing it to a prospective buyer. Made me so mad, I took off all the drain valves, pipes, angles, etc to get to the tanks(s).

Yup, it was the cutout piece that would sometimes float (?) to the opening and lay across the outlet while other times would drift off to the side. Finally fished it out and that solved it. BTW, that buyer never came back

HTH

[Zebra Gorda]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by M&EM:
Thanks for responses.

Last motor home had same grey water drain pipe size and flowed quite freely. This one doesn't flow very well even from the fullest tank levels.

NRV was willing to add an additional vent thinking that was the problem even after warrantee was over. I refused it since it seemed like too much

major work and too many things to mess up in the process and not enough evidence that was the problem.

Yes, I have had side black panels off and thought about adding some slope to the long flat tank. Too difficult!

I added 2 spray heads near the level sensors similar to those used in the black tank for flushing. These seem to keep the sensors working correctly.

I do have a tiny video camera that could possibly fit in one of those openings. So I may try that "goofy" idea Steve. The thought of a hole cut out now seems to be the only explanation for the observed drainage variations I see. Not sure how I would get it out if there was a cut out in there. </div></BLOCKQUOTE>

[RattlenRam]

M&EM I have a 2006 Dolphin with the same problem, I am trying to solve the problem on mine. I will post here if I solve it. Good luck to both of us.

[Rick 2005 Dolphin 5376]

No problems with our 05 Dolphin 5367. Check all the vents under the sinks. Check the vent on the roof. When I bought ours, it didn't even have a vent on the roof. When you say slow, how slow is slow? Ours empties in just a few minutes.

[Jeff H]

We found the notorious chunk of plywood (cutout) was slowing our black drain...so you've probably got one in your grey.

[M&EM]

Slow was more then 10 minutes and still pouring out slowly.

Finally cut a 3 inch hole in the grey tank at the vertical end facing the street side.

The tank was clean as a whistle.

The central roof vent was not overly down into the tank and not an issue.
I also worked a plumbers snake up thru the gate valve and main outlet pipe. I could see the snake clearly in the tank. There was no cutouts or anything in there.
Even with water filled up to the newly cut hole, drainage was just slow. Eventually draining complete.

The tank is only 4-5 inches tall and just won't provide more then a lazy flow.

Contrary to what I thought, the tank does have a low point close to the centerline of the coach and about where the drainpipe is connected. So I can't fault the design. The weird shape of the entire tank may have some local vent issues when the tank is absolutely full.

The shape and position of the drain pipe would suggest that elevating front of coach would assist in drainage. I'll try that next time we use it.

Marty

[RV 4 2]

I have the same issue with my grey tank where sometimes it drains fast and others it drains slow. My coach is new as of July 07. Sometimes it will drain to empty and others it will drain slowly and after 10 minutes, it is still draining really slowly. I need to figure out how to look up there and see what is going on. then if something is blocking it, how to fish it out. If I have to fish something out, anyone have any suggestions?