I have a small 1 inch hairline crack in my fresh water tank. I have determined from other threads plastic welding is the only way to fix the crack. Have also found reference to plastic welding with a soldering iron working very well. My local RV repair place guesses approx 30 to 45 minutes for the repair at $72 hr.
Should I pay for the pro repair?
Should I try the soldering iron method? This would give me pride of the DIY. However since the tank is infloor it is not easy to revisit if my repair is not sufficient. Took about 2 hours to get the tank out and I would expect about the same to reinstall.
The most consistent concern with the plastic weld seems to be making sure I use the same type of plastic, my tank does not have a plastic type stamp. I have some guesses as to type. Any idea what plastic type was used in a 1971 caravel tank?
Thanks,
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Mike Martin
1971 Caravel
2000 Toyota Tundra
Black unknown origin Dog
If it were me, I would weigh the cost of a new tank vs the repair by a professional.
Is there a guarantee with the professional repair?
Has the age of the tank made the plastic brital and will it break again after the repair and the install?
Would a new tank be more flexable and better able to handle the rigers of trailer life such as hot summer, cold winter, road vibration and flexing?
Although, I can hardly wait for the replies to your delimma. This should be entertaining.
I am working on a solution for you ... are you restricted by a budget?
Budget is not the issue, just pride that I could do the repair myself. But I don't want to regret the decision. Looks like $72 would be the high side of the repair with the RV shop.
Quote:
"If it were me, I would weigh the cost of a new tank vs the repair by a professional.
Is there a guarantee with the professional repair?
Has the age of the tank made the plastic brital and will it break again after the repair and the install?"
No guanrantee on the work. Probably tough to find a replacement, would most likely be custom and expensive. The tank is an infloor model that has about a 3" by 3" grove to accomodate a floor beam. Pretty specific dimensions.
The plastic seems very plyable and in great shape for 30+ years old, or even if it were a few years old. No indication of being brittle. I would think the proper technique would be a lasting fix.
__________________
Mike Martin
1971 Caravel
2000 Toyota Tundra
Black unknown origin Dog
I love West System Epoxy. If I were to repair the tank I would rough up the surface with a 60 grit sandpaper, put a coating of epoxy on the surface to be repaired, cut a suitable size piece of fiberglass cloth to cover the wetted area and recoat the glass with epoxy. When the epoxy had cured I would repeat the coating until there were 3 coats of epoxy over the glass. West System has a website and are very good about offering help.
__________________
Keep the shiny side up. WBCCI # 3485 Region 3 1stVP
Past President Tidewater Unit 111
visit tidewater Virginia's web page @ www.tidewaterwbcci.com
Rick Bell in "Silverbell"
When I was a young girl I used to repair basketballs, heavy plastic beach balls, and misc. plastic toys with a method that I was forced to abandon after my mother caught me. I'd twist a clear plastic bag (dry cleaner bag, trash bag, etc.) into a narrow wick shape, set fire to one end of it and let the burning plastic drip onto the hole or area that needed repair. I just blew out the small blue flame after a few drops of plastic had hit their target. Worked well most of the time, but I'm sure it gave off horrible toxic fumes and of course I could have set the house on fire. I'd think that your tank material would have to be made of a food grade plastic - like a milk carton.
The fiberglass repair described below sounds far safer to me and more likely to be flexible enough to withstand the vibration of driving down the road with a half tank of water sloshing around. On the other hand if the original crack happened without an obvious cause, I'd go with replacing the tank because if there's one weak spot, there could be another. Many of the brave folks on this forum have relocated and/or resized when replacing tanks, so you might not have to find an identical tank.
I had the same problem last year in the fresh tank in my 66 Overlander. What I found to work very well is the following. Go to the local NAPA parts store, buy the radiator/gas-tank repair kit. Cost about 10-15 bucks. Drill a small hole at the each end of the crack( this will stop THAT PLACE from cracking more). Use the repair kit per-instructions. Less than 15 minutes you are done!
Made the decision, when taking into account most feel the water tank is inexpensive to replace I decided to try the repair. Worst case I have to buy a new tank. I agree more cracks could occur but I will take that risk, the tank is really in good shape and not brittle. Using anything but plastic welding (melting) I am pretty sure will not work. This is the second repair of this crack (PO did the other) the previous repair was some type of epoxy with fiberglass cloth repair. It appeared very intact but the epoxy had begun to separate allowing a path for water. It was not hard to work the epoxy free and completely separate it from the tank. Previous repair had roughed up the plastic, so pretty good evidience epoxy will not work well for plastic tank repairs.
So here's what I did -
Gathered -soldering iron, P-tex stick from an alpine ski store, drimmel, fan (ventilation), and razor blade.
I "harvested" various pieces of plastic from the tank that were hanging out from the original mold with the razor blade. That way I knew my first layers of plastic would be a perfect match. Then I warmed up the soldering iron, drimmeled a groove along the crack and let the fun begin. I ran the soldering iron along the crack and got the plastic to a workable temp. This alone would probably been enough. Then I melted and worked the scrap plastic into the repair area. Next I took the p-tex stick, and built up the repair area with additional material. Let the repair cool and filled with water, no leaks yet.
What I learned -
Soldering worked well, but I think it was slightly hot
No need to drill "stop holes" at the ends of the crack. I pushed the soldering iron to the ends and got a good melt
Would not have drimmeled a channel. Instead I would have used the soldering iron point to work to the bottom of the crack.
__________________
Mike Martin
1971 Caravel
2000 Toyota Tundra
Black unknown origin Dog
Glad to hear that you made the repair and hope it holds for just one day longer than forever. I think you will find that the fiberglass repair was made with a polyester material in lieu of epoxy. Best of luck
__________________
Keep the shiny side up. WBCCI # 3485 Region 3 1stVP
Past President Tidewater Unit 111
visit tidewater Virginia's web page @ www.tidewaterwbcci.com
Rick Bell in "Silverbell"
I agree with Andy. If it is plastic and holds a liquid I am going to ingest. I will replace it.
That's just me. I have little patience to repair something again.
When I replaced the dump valves on my holding tanks I replaced the entire valve instead of just replacing the seals. I figured that if the old ones last 27 years, the new ones should last at least that long. No repairs needed on that particular item for 26 more years now!
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I'd twist a clear plastic bag (dry cleaner bag, trash bag, etc.) into a narrow wick shape, set fire to one end of it and let the burning plastic drip onto the hole or area that needed repair. I just blew out the small blue flame after a few drops of plastic had hit their target. Worked well most of the time, but I'm sure it gave off horrible toxic fumes and of course I could have set the house on fire. I'd think that your tank material would have to be made of a food grade plastic - like a milk carton. 
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