Partially plugged gray tank drain!

[whemme]

When I drained the gray tank upon leaving the RV campground on my last outing, the tank drained normally. When I arrived home, I normally refill both the black and gray tanks with clean water twice each tank and drain them to clean them out throughly. When I did this on my last trip, the gray tank then would only drain slowly like there was some sort of restriction in the drainage piping somewhere.

I have a 2002 26' RSB model and this has never been a problem before. I purchased a 10' long 'roto-router' type device from ACE hardware and ran it up thru the gray water drain, thru the gray water valve, thru the four 90 degree drain pipe elbows and then into the tank itself. I ran this device up and out of the tank at least 5 times, each time with the gray tank full of water and of course with the drain valve open and could not remove the restriction nor improve the drainage rate.

The tank now just drains slowly. Maybe takes about 5 minutes to drain the tank wereas it normally takes only 20 to 30 seconds to drain. I am not aware that anything went down any sink or shower drain to cause this restriction. In fact the largest drain hole going into the gray tank system in my coach would be the bathroom sink drain hole which is approximately 1" in diameter.

Anyone have any idea what my problem might be.

[tomdclark]

Bill,

I really don't know what the cause of the problem is nor have I ever experienced this problem, but...

If the drain plumbing is clear (which it sounds like it may be with your 'roto-roroter' efforts) about the only other thing is vent blockage. If the vent is blocked, you get an upside down bottle effect. That is to say you need a souce of air to replace the volume of water going out of the tank. If one is not present, drainage would be nil.

I'm probably totally wrong here, but I hope the thought helps.

Tom

[Mel Wilbur]

Bill,

I was thinking along the same lines as Tom that it could be a venting problem , however I was reminded of a friend that had a fuel tank problem that turned out to be a foreign object in the tank that once in a while ended up covering the outlet line. If that was the case your "snake" may have just moved it a bit and the the pressure of the water in the tank moved it back over the outlet. Have you also checked all the traps for any possible restrictions. Bill, the good news is that it is not the black water tank you have to work with.

[robert newby]

Hi Bill -- I have heard of the plug that is cut out of the tank so as to install the inlet and outlet pipes falling into the tank and plugging the outfall line -- if that is the case I'd call Kim and ask him for his suggestion -- Bob Newby

[whemme]

I don't think the problem with the gray tank is a plugged vent, because if it were that, the water from the tank should initially gush out like normal and then the outflow should slow down as the vacuum builds up in the tank. Also, the tank outflow should start gurgling - that would be necessary to let air back into the tank as the water flows out and none of the above symptoms of a plugged vent is happening.

What puzzles me is that moving the roto-router snake in and out of the tank drain piping as it is draining does not cause any momentary increase in drain rate. You would think this would happen as the snake temporarily moved the restriction aside.

Mel, I have filled and drained this tank so many times now with clean water working on this problem that I think I could now drink out of it - just kidding of course. But, you are right, I am glad it is the gray tank and not the black tank.

Currently I have the coach scheduled into the Born Free factory on August 3rd to address this problem. I will be really curious what they find is wrong.

[lassen]

Bill...Have you read other forums where people have had algae and slime growing in their fresh water tanks to the extent that their water pumps were plugging. With all the soaps and oil and anything else from the kitchen, I can picture what could be growing in our gray tanks.

I would try something like cleaning a gunbarrel with a patch on a rod. Could you attach something on the end of your roto router, run that into the tank and back it out and see what comes out with the patch. If you get anything out then you might be able to attack the problem with some chemical.

Anyway, best of luck and hope you find a solution before going back to the factory. Also we enjoyed meeting you and Marilyn and had a great time at your rally.

Later....Jack

[bcope01]

Bill:

The blocked vent theory doesn't work because all of the drains that drain into the gray water tank act as vents.

I go with the moving obstruction theory. Almost acts like some kind of flapper valve at the outflow from the tank itself. Hmmmmmmmm.

Let us know what the factory finds.

Bill

[tomdclark]

I think all the drains have water filled traps. So the vent theory may still hold.

There could be some syphon action, but I think one would hear some bubbling or something.

[whemme]

Well after driving 78 miles from home to the Born Free factory in Humboldt, IA the slow drain problem dissapeared. Before leaving home, I had filled the gray tank about 1/3 full with clean water so that I could demonstrate the slow drainage problem when I got there, but, evidently the problem just went away during the road trip to the factory.

And I went dry camping immediately after that for 10 days and drained the tank again twice more and again no problem with slow drainage. Don't you just love these kind of problems. Evidently whatever was partially restricting the outflow from my gray tank was dislodged by the 78 mile road trip.

[whemme]

Sam,

I guess you are right about that. Lucky I don't have water tanks in the Bonanza aircraft to deal with.