Cause of holding tank leaks??? - Montana Owners Club

drsmart · 12-04-2010, 04:11 AM

I've read about quite a few members having black and/or grey tank leaks. Has this happened to anyone that generally keeps their tanks empty for travel? I'm not concerned about small amounts of fluids in the tanks for the sake of rest stops between camps. Is it possible that the added weight of fluids while traveling with some flexing of the tank is stressing the attached drain pipes and causing cracks and leaks adjacent to the tank connections? Just wondering if there's a way to reduce the likely hood of developing this problem. I've read at least one member added carpeted support boards under the tanks to soften the constant pounding while driving. Example, those concrete highways with expansion joints.

ols1932 · 12-04-2010, 05:38 AM

Quote:

quote:Originally posted by drsmart

I've read about quite a few members having black and/or grey tank leaks. Has this happened to anyone that generally keeps their tanks empty for travel? I'm not concerned about small amounts of fluids in the tanks for the sake of rest stops between camps. Is it possible that the added weight of fluids while traveling with some flexing of the tank is stressing the attached drain pipes and causing cracks and leaks adjacent to the tank connections? Just wondering if there's a way to reduce the likely hood of developing this problem. I've read at least one member added carpeted support boards under the tanks to soften the constant pounding while driving. Example, those concrete highways with expansion joints.

I believe it could be with the way they are fitted in the RV. Ours are sitting on cross members of the rig. Each tank has a flange about one-inch wide that sits on the cross members. If you happen to travel with a full tank and the roads are rough, it may be enough to split the tank right under the flange. It's just my guess since I've had both tanks replaced and they had both leaked in the same approximate position.

I don't know that using any other means of fastening the tanks in helps because all the weight of the tank is on the flange sitting on the cross member of the rig.

We had our gray water tank replaced in July and it's leaking again. I called the dealer and he will take care of it next summer when we go through our home town. We do not travel with full tanks. The only thing in the tanks comes from when we make a rest stop or make an overnight stop.

I hope this helps.

Orv

8.1al · 12-04-2010, 06:05 AM

We travel with little or no liquid in the tanks and have had the galley and black tank develop a crack around the outlet

awaywego · 12-04-2010, 06:27 AM

The company that makes the tanks told me they were designed to have straps under them for support but Keystone refuses to install them. They depend on the lip to hold them and that is not enough support. I had to have a new gray tank installed and when filled to check for leaks the tank was round on the bottom. I travel with them empty now.

drsmart · 12-04-2010, 09:29 AM

Orv. I have some photos of the tanks in our unit and can see what you mean.
You all travel with them empty. So looks like unless the straps are added or the tanks are redesigned with reinforcement where they've been cracking, the problem isn't going away.

scductman · 12-04-2010, 03:53 PM

I put braces under mine with rubber armoflex under the tanks. they would bow down when full but the top would rise up alot when full also. they will make the floor of the basement raise up when full and that causes the pipe going in the top to flex every time they are filled and emptyed. I installed rubber nohub bands on mine to protect them with no problem since. I travel with mine empty. a little in the black for the DW.
bobby

richfaa · 12-06-2010, 03:39 AM

Like 8.1 al we travel with near empty tanks. We have had 2 black and 1 gray tank spring leaks. The leaks occur around the inlets and are caused...IMP by flexing when traveling and improper bracing.
The tank folks " travel star" say the tanks should be strapped......However MY 3400 was not designed to have the tanks strapped as per travel Stars spec's. We were there.

We did have the leaking black and gray tank replaced at the fall rally. NOT by keystone but under extended warranty by a repair facility that knew how to provide addditional support and bracing to the tanks.

drknapp · 12-06-2010, 03:59 AM

I find it interesting that Keystone hasn't taken steps recommended by the tank manufacturer to help prevent any leaks. It doesn't seem like it would be a major task (or cost) to add some straps to them.

drsmart · 12-06-2010, 04:57 AM

The one holding tank that I can see the label on shows the manufacturer Ameri-Kart with P/N HT541. Based on the model I could look up the specs on their site. It's positioned closest to the galley and is 40 gallons. I sent Ameri-Kart a request for information regarding the tank failures and proper install over the week-end. Waiting for a reply.
Rich. I wonder if Keystone switched from travel star because of the problems or because Ameri-Kart gave them a better price?
I'm also curious about the bathroom grey and black tank size. If all three of the holding tanks are HT541's, the brochure specs from Keystone wouldn't be true - 50 gallons black and 93 gallons grey. If the two under the bathroom are 50's, then we're good. I'll have to try to get to the labels sometime.

carlson · 12-06-2010, 06:22 PM

Yes part of the problem it that the tanks are just supported at the top and when the tanks fill, they start to expand, like filling a balloon with water.
But I feel the other real problem is that the tanks, valves, piping are all glued together and there is no flex joint, (rubber coupling).
As we travel down the road the unit is constantly flexing, twisting. the plumbing is solid glued with no ability to flex.
When I put in the new tanks all the pipes have rubber couplings in the piping.
So far so good.
E. Sven

camper4 · 12-07-2010, 12:53 AM

Holding tanks are like so many other things Keystone cuts corners on.
I like the ideas of flex couplings and added supports. I had one failure on our 2955. When I have a failure on our current 3075, I will try do both things. I should fix them before failure but I hate getting to them.

nowinter · 12-07-2010, 02:36 AM

Richfaa: Can you provide information regarding the company that replaced your tanks at the Fall Rally? Were you able to see the installation and did they use flexible couplings? In other words, what gave you confidence that they had experience.

Thanks

drsmart · 12-07-2010, 03:09 AM

I was impressed with the tight fit where the kitchen drain pipe went through the floor, but after realizing the tanks may have movement during travel the problem develops.

I think something like this is what other members were referring to:http://www.fernco.com/plumbing/flexi...pansion-joints

I sent Fernco an explanation of the problem and asked for their recommendation for a coupling best suited for this.

berridge · 12-13-2010, 03:05 PM

There seems to be two reasons for the holding tank failures. Since the tanks, plumbing and fixtures are all attached to the chassis in one way or another I wonder if the main cause is the deformation of the tanks as they are filled and then emptied rather than vibration. This would cause certain areas such as corners under the lip and around the outlets to be bent back and forth resulting in stress cracking. The galley tank in my 09 3075 has failed at the corner under the lip. It has no bracing and simply hangs from the lip. I am in the process of adding a couple of braces before I attempt to patch the crack.

drsmart · 12-13-2010, 04:36 PM

rvberr. That certainly could be a reason. We have tanks manufactured by Ameri-Kart. Their web site has an installation document that suggests no bracing when tanks are installed as in the Montys. The perimeter of the tank resting on the chassis. I've submitted a request to them for suggestions to help prevent tank failure but had no reply. This is a link to the installation document.
The part that makes me wonder is the directions for testing a tank. It says not to use a liquid soap or detergent solution as this will cause stress cracking. Who doesn't use soap to shower or do dishes. Does this mean that using soap will cause the tanks to crack over time?
http://www.ameri-kart.com/rv_catalog...lding_tank.pdf

nailbender · 12-14-2010, 02:00 AM

Dave, Have you received a reply from Fernco? The Frenco connectors appear to have a lot more movement than a standard no-hub connector. I would like to install a flexible connector at the inlet and outlet of the tanks, but it would be a major re-plumbing job.

drsmart · 12-14-2010, 02:58 AM

Nothing yet Don. I'm probably not high on their priorities. If I had "Keystone Corporation" in my signature, I probably would have gotten an answer back within 10 minutes.

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