Water Leak from Gray Tank? - Montana Owners Club

RKassl · 08-23-2018, 03:51 PM

It seems like there is always something going on with the RV. Had a water leak from the belly of the camper. The Mobil Tech opened the belly and saw water coming out around the valve. Again replaced the valve, continued to leak, replaced with a new valve and still a leak from the bottom of the valve. So two valve replacement did not stop the leak. What we found was that when the gray tank reached 2/3 full it would to leak from the blade valve area. If I run with the gray tank valve open, I get no leaks from the belly. So that is what we are doing right now. Could I have a tank crack in the neck of the gray tank where it bolts to the blade valve? Also he said that the gray tank can be moved like it is not bolted down. Can this be true? We have no problems with the black tank. Any info or suggestions would be welcomed.

jcurtis934 · 08-23-2018, 04:11 PM

The tanks aren't bolted down. They sit on two metal rails at the top outward flange of the tank. Whether the tank has support under the tanks per the tank manufacturer is highly unlikely as keystone wasn't doing that and still may not be doing it. The tanks "balloon" as the tank has more and more liquid in it. I guess it could change the valve seating if the fittings on each side of the valve wasn't glued on properly. My valves are connected on each side by rubber no hub connectors that I installed. I currently have a shower valve that leaks slightly and I need to tighten the four bolts on the valve more to see if it stops the leak. I might have just gotten a bad valve the last time I changed the two up front. Good luck on yours.

Montana Man · 08-24-2018, 10:41 AM

Keystone does not mount tanks according to the manufacturers recommendations. Therefore they are prone to cracking and leaking. If tank replacement is necessary, beef up the mounting above and below the tank.

leemedic · 08-24-2018, 11:03 AM

I have had two of my grey tanks crack and leak. Had to replace them both. One actually exploded while we were in it. Loud pop and shook the Montana

rohrmann · 08-24-2018, 12:17 PM

It sounds like you may have a hairline crack in the tank side flange, and it's not visible when you have the valve removed, but when you get the weight of water in the tank, the crack opens just a little bit and you see the leak. You may need to replace the flange.

I had a leak in my gray tank a couple years ago, and fortunately it was on the bottom of the tank, and I was able to repair it with Plastimend. I then installed a couple more braces across the frame under the tanks so I now have a brace under the black and gray tanks every foot. I then placed blocks between the tanks and braces, the blocks glued to the bottom of the tanks, and then removed the braces, re-installed the coroplast and then the braces. I now have the tanks fully supported and have no fear of having full tanks. The tanks are only supported from the factory by the two lips at the top of the tanks and and are not screwed or bolted but are just suspended by a steel channel on the sides at the lips, so they can move a little bit.

RKassl · 08-24-2018, 04:47 PM

I have learned so much over the years starting with my 2005 Montana. But I am shocked that Keystone does not secure the tanks!!!!! What the hell. The mobile tech that was working on my problem told me he could actually move the gray tank. When it is repaired by my dealer, can they secure the tank better????
Thanks!

rohrmann · 08-24-2018, 05:27 PM

There are problems with securing these plastic tank too tight. If you drill holes in the lip at the top, you risk causing cracks to develop at the holes. The way they are installed is a good start, because they are able to expand and contract with temperature changes. I believe the tank manufacturers want the tanks supported from underneath, so the weight is not all at the lips, they just aren’t strong enough. I’m not sure how the RV manufacturers are supposed to support them from requirements of the tank specs, but just hanging them like in our rigs is definitely not the proper way.

jeffba · 08-25-2018, 04:30 AM

Bob do you remember the specs on your metal supports?

Eagleback · 08-25-2018, 05:12 AM

My 2014 has 1 full length support bar that runs from one side, under both tanks and then to the other side and bolted to the frame and my tanks sit on that support but also are suspended by there flanges on the tanks, I know my grey tank has a small crack somewhere on the top because when the tank is filled to the top water runs out, but i cant see it. Im on the fence as if should i lower the tank and fix it or should i just not let the tank get completely full anymore.

jeffba · 08-25-2018, 06:18 AM

Quote:

Originally Posted by Eagleback

My 2014 has 1 full length support bar that runs from one side, under both tanks and then to the other side and bolted to the frame and my tanks sit on that support but also are suspended by there flanges on the tanks, I know my grey tank has a small crack somewhere on the top because when the tank is filled to the top water runs out, but i cant see it. Im on the fence as if should i lower the tank and fix it or should i just not let the tank get completely full anymore.

Okay first thought is a stitch in time saves....
Or Do you feel lucky......

Seriously though You may want to try and figure out if you did anything that may have contributed to the cause of the crack. Not saying you abused it, but realistically what may have been the cause.

If you think there is a possibility you may do that again, the leak could get much worse. and that may influence your decision.

mazboy · 08-25-2018, 07:55 AM

The tank could be cracked.

Need to get tank out to see what is going on.

If you get replaced, cost will be about $1200.

RKassl · 08-25-2018, 08:42 AM

Quote:

Originally Posted by rohrmann

It sounds like you may have a hairline crack in the tank side flange, and it's not visible when you have the valve removed, but when you get the weight of water in the tank, the crack opens just a little bit and you see the leak. You may need to replace the flange.

I had a leak in my gray tank a couple years ago, and fortunately it was on the bottom of the tank, and I was able to repair it with Plastimend. I then installed a couple more braces across the frame under the tanks so I now have a brace under the black and gray tanks every foot. I then placed blocks between the tanks and braces, the blocks glued to the bottom of the tanks, and then removed the braces, re-installed the coroplast and then the braces. I now have the tanks fully supported and have no fear of having full tanks. The tanks are only supported from the factory by the two lips at the top of the tanks and and are not screwed or bolted but are just suspended by a steel channel on the sides at the lips, so they can move a little bit.

Its interesting that you mentioned the flanges where the valve bolts to. The mobil tech thought the same. Can the flange from the gray tank be replaced?

Eagleback · 08-25-2018, 09:18 AM

Quote:

Originally Posted by jeffba

Okay first thought is a stitch in time saves....
Or Do you feel lucky......

Seriously though You may want to try and figure out if you did anything that may have contributed to the cause of the crack. Not saying you abused it, but realistically what may have been the cause.

If you think there is a possibility you may do that again, the leak could get much worse. and that may influence your decision.

I dont know what caused the crack. It was not cracked or leaking before and everything thats on my previous post is factory installed. maybe the support bar is the culprit itself. or bad install. I have had the coroplast down because i noticed water dripping from the bottom and thought it was the black tank sprayer leaking and I looked up in there and everything looks ok from the bottom. I dont know if i want to take on the job of lowering it or wait until i find help to do it. but it only leaks if the tank is completely full.

RKassl · 08-25-2018, 10:23 AM

Now that I know how the tanks are suspended I won't say secured, I can see how bouncing down the highway can stress out the neck area of either tank because the tank may move but not the joint to the waste water pipe. I pampered my tanks, always try to travel with them empty. It is very disappointing to have this happen.

RKassl · 08-25-2018, 12:52 PM

Here is food for thought. If the tanks are not fastened down, would it actually be better to have them at least 1/3 full to keep them in place and stop them from moving around?

rohrmann · 08-25-2018, 04:02 PM

Quote:

Originally Posted by jeffba

Bob do you remember the specs on your metal supports?

I'm assuming you are referring to the ones I added. First, there were already two steel channels, approximately two feet apart, which I guess were installed to support the coroplast. I added two 1 1/2" X 1 1/2" angle steel I purchased at Lowe's. I think they were 5 feet long, and to span the frame I had to cut 3 or so inches off of them. I installed one half way between the existing channels, and the other one about a foot forward of the front channel. The existing channels were installed with the TEK screws, and that is what I used for the new braces. All I had laying around was some 2 X 4's, so used a couple of them to start with. They are 1 1/2" thick. I then purchased some 1/2" foam insulating board and made blocks 1/2", 1", and 2" for the other three positions. The tanks have a 1/2" per foot slope on the bottoms, so the reason for the different dimensions. With the braces all installed, I used silicone to glue all the blocks to the bottom of the tanks, and after setting, removed the braces, put the coroplast back up and put the braces back on. I suppose I could have added even more braces, but at the time it didn't appear to be needed, and so far, haven't had any new issues.

rohrmann · 08-25-2018, 04:12 PM

Quote:

Originally Posted by RKassl

Its interesting that you mentioned the flanges where the valve bolts to. The mobil tech thought the same. Can the flange from the gray tank be replaced?

When we were still under warranty, our black tank drain valve broke which also broke both the flanges. I managed to get it to the CW west of Boise, ID for repairs. Their night crew, (this was in July and they were swamped with work), was able to make the repair. It looks like they used new flanges, and were able to carefully cut the broken flange off of the nipple on the tank side and glued the new one on. I couldn't tell if they used new parts to attach the new flange on the discharge side of the new valve or were able to remove and replace that flange also. I was surprised that they used a hard coupling to put everything back together instead of a rubber coupling with clamps.

Mark7 · 08-29-2018, 07:17 PM

I've either replaced (2) and repaired the galley thank in my '05 Montana. Not a big job, but takes some time. As others have said they "hang" from the flanges where the top is glued on to the rest of the tank.

I am fine with that, and have had no issues since the repairs, however... I never travel with any significant amount of water in them because of the weight. I will put 4 or 5 gallons of water in the black tank for "slosh" rinsing for the next cycle, but both gray and galley are empty.

There is a lot less stress on the tanks with that practice.

Denny and Angie Miller · 08-29-2018, 08:26 PM

I have found a crack at the tank outlet flange on my previous cougar. I repaired it with this:
https://www.amazon.com/Permatex%C2%A...=permatex+9100

Make sure you get this exact version (Permatex 9100)...it comes with a little fiberglass cloth, sandpaper and a brush. it's a 2 part epoxy that gets REALLY hot while curing, so be prepared for that. I love this kit so much, I keep one on board for emergency repairs.
It's worth a try before replacing the whole tank...

Montana Man · 08-29-2018, 10:48 PM

My buddy with a Keystone product went through several black tanks. The second to the last tank was installed at the dealer. Before we towed the trailer off the lot we began to fill it right in front of them. It broke open. At that point they said it was our fault! Long story short, the tanks hang on metal brackets. The factory spaced the brackets too far apart thereby allowing the tank to hang from the very edge of its flange and with weight, split the tank along the seam. We took the trailer to a reputable shop and they cut and rewelded the brackets closer to the body of the tank. Problem solved. The tank is still not mounted according to the tank manufacturers Rx as there are no supports under the tanks.

You may also like: