Warning--- Don't Look - Montana Owners Club

Billhorn · 09-26-2019, 06:34 AM

A lesson I'll never forget. I have been trying to figure out why there would occasionally be some dripping out the bottom of our fifth wheel (2003 Montana 3670RL). I bought an endoscope but that just didn't show much. So I decided I just had to fugure out a way to peek inside the bottom to see if I can tell what is going on. So I removed a couple of screws at the front from the very thick and ridgid plastic sheeting. I got my little flashlight all ready and got in a good position to stick my head up in there to try and look for a problem. Of course there was an ocean of nasty that came flowing out as soon as I pulled the bottom down a bit. I managed to not get a face full but got soaked. Lesson learned. So I took a lot more screws out so I could drop one full side of the bottom and got a clear view of the leak. I'm wondering what the group recommendations would be for a patch. Online I seem to only find stories from unsucesfull attemps to stop leaks.

**Carl n Susan** · 09-26-2019, 11:02 AM

Many here have had success using a product called Plasti-mend. Here are a couple of Posts about its use. Do a Search on "plasti-mend" and you will find a lot more.

http://www.montanaowners.com/forums/...ht=plasti-mend
http://www.montanaowners.com/forums/...t=plastic-mend
http://www.montanaowners.com/forums/...t=plastic-mend

Hblick48 · 09-26-2019, 02:46 PM

My Montana has the same style tanks as yours (made by TravelStar). 2 years ago, before we began a cross country trip, the grey tank started to leak around where the discharge fitting is glued. I used the plasti-mend ABS kit to repair. By the end of the trip, the leak returned.

I purchased and installed a new tank from rvandvansurplus.com, installed it, and everything was great. The original tank was model 295. Their price was $199 plus $120 shipping (bend over).

During our most recent trip, the black tank began to leak. I ordered a new one (model 294) from rvandvansurplus. When I called to check on my order, I was told that they could no longer supply the tank, mfg wouldn't make one.

I called Trekwood, and fortunately they had one. Their price was $499 with free shipping (bend over again). I ordered it and installed..no more leaks.

While I was in there, I installed bracing on both tanks to help minimize the chance of another leak.

My experience says you need to install a new tank.

Billhorn · 09-26-2019, 03:50 PM

Our Montana doesn't move from it's current location, so I'm hoping a patch will work. I'm pretty new to this RV stuff and tackling a black tank replacement is out of my league right now. We have no way to move it so I'd have to see if someone would come out and replace the tank on site if my patch fails.

h2ojocky · 09-28-2019, 12:08 AM

I patched my galley tank using ABS glue, shavings from ABS pipe, and screen door mesh
Check you tube videos

Billhorn · 09-28-2019, 01:16 PM

I'm gonna try a patch but I wanna prepair for the worst. Did you replace the tank yourself? It looks dooable with the right replacement tank. I called TravelStar and was told they only sell to manufacturers. Then I called Trekwood and was told "777102800 Tank - Holding - 24" x 63" x 8" - Right Side Drain $499.99 Includes shipping". Do you know if this is the same tank you used? Was your tanks directly across from each other like mine are? That makes me worry about the pipes lining up.

h2ojocky · 09-28-2019, 02:01 PM

I did not replace my tank, I repaired it. So far so good! My tanks are not next to each other like yours. I have some photos but can't figure out how to send them.

Hblick48 · 09-28-2019, 02:33 PM

Quote:

Originally Posted by Billhorn

I'm gonna try a patch but I wanna prepair for the worst. Did you replace the tank yourself? It looks dooable with the right replacement tank. I called TravelStar and was told they only sell to manufacturers. Then I called Trekwood and was told "777102800 Tank - Holding - 24" x 63" x 8" - Right Side Drain $499.99 Includes shipping". Do you know if this is the same tank you used? Was your tanks directly across from each other like mine are? That makes me worry about the pipes lining up.

I'm pretty sure your setup is exactly the same as mine, grey and black tank face each other and are connected the same as in the picture, both are 24x63x8.

In addition to dropping the coroplast on the bottom, I also removed the basement floor in order to gain access from the top. To do this I removed the carpet. I used a circular saw set to 3/4 inch depth and cut the floor exactly in half. The pipes coming out of the top of the tank go through round holes, so you CAREFULLY need to cut from the hole to the side wall so the board can be removed, Remove all of the screws holding the floor and side boards. Pull the floor up from the center and slide sideways until you clear the pipes and remove.

In order to remove the tank, remove the 4 bolts holding the valve in place, you don't need to remove any other fittings, so don't worry about alignment. Remove the cotter pin holding the valve to the valve extender, and pull out the handle and extender. Remove the sensor wires (noting which color wires are attached to what sensor..there are 4) and cut the pipes coming out of the top of the tank about 4 inches above the tank.

Pull the tank up and out from the top. Once the tank is out, you will see cross members screwed to the frame. Remove the cross member farthest from the center.

You will need to purchase a spigot flange for the valve, and splice connectors for the pipes coming out of the top of the tank. Also, you will need to purchase rubber fittings for the top of the tank from Trekwood.

Carefully measure where the pipes come out of the old tank. You will need to use a hole saw (Harbor Freight) to cut openings in the top of the new tank exactly where they were on the old tank. Insert the rubber fittings in the top of the new tank.

Install the new tank from the top as close to the side wall as possible so you can slide the tank sideways. This should give you enough clearance to glue in the new valve flange, Make sure it is pushed into the new tank the same as it was on the old one. Quickly, before the glue takes hold, rotate the valve flange so the bolt holes line up with the flange on the discharge assembly. Install the valve (sliding the tank) and then replace the tank support.

You will need short lengths of abs pipe and 45 degree fittings to go from the rubber fittings to the top pipes. Use the splices to re-attach the pipes you cut off. Make sure you push the pipes fully into the rubber tank fittings. I used dish washing liquid to lubricate. Re attach the handle.

Attach a piece of 2x4 to the underside of the basement floor you didn't remove, leaving 1/2 of it protruding out so you have something to screw the removed floor to.

Replace the floor and screw it in place. Replace the coroplast and you're done.

If you are not a good handyman, this may be a difficult repair!

h2ojocky · 09-28-2019, 02:59 PM

Billhorn, if your tank just has a small crack, I would recommend fixing it like I did. I believe that fixing like I did is stronger than the original. The ABS glue basically welds the fix to the tank. It is a simple fix. The hardest part for me was removing the coroplast. If you need more info send me a private message and we can talk via phone.

Billhorn · 09-28-2019, 03:00 PM

Did you take the tank out the top because it is easier that way? All the youtube videos I've studied take the tank out the bottom. Or is that the way that it has to be done with our type of Monty? I'm a retired bricklayer that is used to working on dry sandy things that don't stink and with a lot of room to move, might look to see if any service guys will come out to the site. Thank you very much for the detailed directions.

Hblick48 · 09-28-2019, 03:27 PM

Quote:

Originally Posted by Billhorn

Did you take the tank out the top because it is easier that way? All the youtube videos I've studied take the tank out the bottom. Or is that the way that it has to be done with our type of Monty? I'm a retired bricklayer that is used to working on dry sandy things that don't stink and with a lot of room to move, might look to see if any service guys will come out to the site. Thank you very much for the detailed directions.

If yours is like mine, there is a piece of angle iron that is welded to the bottom of the frame for support (I think I see it in the picture on your original post). They only welded a support for the black tank, none under the grey. Makes it really hard to remove black tank from the bottom.

Another "cheep" Keystone technique to save a few $$$. Why didn't they install a support for the grey tank? Tank mfg specify that the bottom of the tank needs to be supported. Probably because a leaking grey tank is not as nasty as a leaking black tank!

jcurtis934 · 09-28-2019, 05:52 PM

Plastimend gives very clear diction about tank needing to be empty with no moisture in the crack, a larger than the Crack needs to be roughed up with sandpaper and the area cleaned with the cleaner before laing on a thick coat of the cement and embeding the fiberglass screen material, followed by more cement. If multiple coats are done and the Crack area is not taking up moisture due to the tank being drained properly. The repair should be successful. Of course, it doesn't help matters that keystone never followed the tank manufacturers installation instructions for the tanks to be supported properly.

whitesub93 · 09-29-2019, 11:19 AM

I used this on the inside of a hot tub and it has held up for 5 years now.
https://www.homedepot.com/p/J-B-Weld...8277/202528473

Hblick48 · 09-29-2019, 11:54 AM

The problem that caused my grey tank leak 2 years ago and the black tank 2 months ago was where the tank discharge fitting is installed into the tank. Both were cracked at the joint. From the picture, Billhorn's leak is in the same spot.

The lower tank material is actually very thin...maybe 1/16". The fitting is much thicker. The tank will flex as it fills up and again when it is drained. The fitting doesn't flex so eventually a crack will develop. Properly supporting the bottom the tank minimizes the chance of the tank cracking. The single angle iron Keystone installed is not sufficient to inhibit the flexing.

As I discovered when I tried to fix the grey tank 2 years ago, eventually the patch will crack since the original crack is just covered up. The flexing still occurs, and the original crack is the weak point causing the repair to eventually crack and fail.

An internal repair would be more successful than an external repair, but I don't know how you get inside the tank to clean and apply the repair materials. The external repair will work for awhile, mine did. It held until the end of a 2 month cross country trip during which the tank was continually filled and emptied. Add that to the earthquake effect of towing 6,000 miles..you get the picture.

Since Billhorn's rig is stationary, the repair should last longer. Just be prepared to re-do it when it fails again. You could probably keep patching it for a long time.

JOSEPHSTILESCCS · 10-02-2019, 02:20 PM

Looks like the crack is where the fitting attaches to the tank. Very common due to the lack of support on the plumbing lines and Valves. A bump in the road could of caused this. Another common problem is freezing. Just a very small amount of water in the tank with lack of anti freeze can cause this. Unfortunately the only lasting fix is to have the tank replaced. When you look at how they put these things together sometimes it just leaves you scratching your head. An extra support their or bracket there and non of this would ever be a problem, Simply poor quality control trying to get as many out the door as possible. We oow and augh at the amenities when we go to buy these things. The problem is most of the crappy work is hidden and you will never see it until an issue like this. Feel for you Buddy

RRman · 10-02-2019, 03:09 PM

I replaced my Black Tank Summer 2018. It had cracked about 3/4 of the way around the outlet fitting (Honey Wagon suction with a VERY full tank the likely cause) and my less than ideal Plastimend fix and subsequent Flexseal Tape would not stop the leaking... So RV surplus took 2 months to get me a new Tank. Upon removal I also discovered The 12 year old Tank also had a small/degraded looking HOLE (not cracked) in the corner closest/opposite the outlet (how did that happen??). My Tank support bar/beam was just screwed in so just cutting the vent pipe and outlet plumbing was all it took to remove the tank. Replacement was a struggle to push the Tank Flange up/into the fixed brace under the floor insulation and its just a hair lower after putting up the removable brace - a two person job.
I added some more supports and used Flexible Rubber fittings from Outlet to drains/valve and between the Toilet downpipe and inlet tank fittings. Fitting a flexible rubber fitting from the tank to the outlet vent pipe in the most inaccessible top tank corner was another installation struggle.
While the bottom was down I also re-plastimended around the Grey tank outlet and braced that tank too.
Have not noticed leaking while camped, but a few months ago after being in storage I noticed a gallon or so of water leaked out the belly while pulling the trailer out of storage so something must be leaking slightly albeit not visible on 3 RV trips since then...
We Never go more than 2 nights on the Gray tank or 7 days on the black. But have traveled with 2-4 days in the Black tank (like to have enough in it to dump well).
THESE TANKS Are so CHEAPLY made! But I suppose good enough for weekenders...

lmf580 · 10-02-2019, 03:25 PM

Quote:

Originally Posted by Billhorn

A lesson I'll never forget. I have been trying to figure out why there would occasionally be some dripping out the bottom of our fifth wheel (2003 Montana 3670RL). I bought an endoscope but that just didn't show much. So I decided I just had to fugure out a way to peek inside the bottom to see if I can tell what is going on. So I removed a couple of screws at the front from the very thick and ridgid plastic sheeting. I got my little flashlight all ready and got in a good position to stick my head up in there to try and look for a problem. Of course there was an ocean of nasty that came flowing out as soon as I pulled the bottom down a bit. I managed to not get a face full but got soaked. Lesson learned. So I took a lot more screws out so I could drop one full side of the bottom and got a clear view of the leak. I'm wondering what the group recommendations would be for a patch. Online I seem to only find stories from unsucesfull attemps to stop leaks.

I have used Plasti-mend on two tanks. Follow the instructions and make sure the tank is dry. I used a shop vac blowing in the drain. There is a short working time with plastic mend (5-8 min.) Use disposable brushes. Three coats is recomend. My repair was 4 yrs ago, no leaks yet.
Plasti-mend ph # 800-821-1835.
Web: plasti-mend.com

Mark7 · 10-02-2019, 06:55 PM

I replaced both my grey and black tanks as they were old and pretty cracked up. My black tank was cracked along the top edge where the lid is "welded" on. I was told it likely froze when full at some point... not while I owned it.

Another piece of advice I got was not to travel with full tanks as this puts more stress on that area of the tank.

I did all of the work myself... from the bottom side and it was not a real big deal. I did have to cut one cross brace out with a side grinder and I welded it back in place after replacing the tanks.

I did fix a small leak in the galley tank using the ABS pipe filing and glue method. It worked great!

I also installed Horst Miracle Probes in all 3 tanks while I had them out. That has worked out well.

Good luck!

Baron of Beef · 10-02-2019, 07:34 PM

Our 2013 Mountaineer had a big gap where the toilet pipe entered the tank. Research lead me to JB Weld Water Weld. The factory confirmed it would work on ABS, can be applied wet, and has 900 psi strength. So far, so good. While I had it apart, I added an extra layer of the reflective bubble insulation for our Canadian shoulder seasons..

Billhorn · 10-03-2019, 06:35 PM

Quote:

Originally Posted by lmf580

I have used Plasti-mend on two tanks. Follow the instructions and make sure the tank is dry. I used a shop vac blowing in the drain. There is a short working time with plastic mend (5-8 min.) Use disposable brushes. Three coats is recomend. My repair was 4 yrs ago, no leaks yet.
Plasti-mend ph # 800-821-1835.
Web: plasti-mend.com

I get my order of Plasti-mend tomorrow. I like your idea of using the shop vac blowing into the drain to make sure the inside of the crack is dry. I also have thought of running the shop vac sucking on the drain line with a rag shoved in the pipe around the shop vac hose to seal it off. I thought this would put a slight negative pressure in the tank that would tend to draw the Plasti-mend into the crack slightly. I have also noticed the support strap that holds up the main drain line is loose and isn't supporting the 6 foot pipe. Looks like it was left that way the last time somebody worked on something there. When any of the tanks get drained that pipe must get pretty heavy and it must put a strain on the tank if it isn't supported properly. Gonna fix that.

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