# RV Polyethylene fresh water tank crack repair



## DallanC (Jan 13, 2009)

So I noticed a small drip leak on my Trailer just prior to going camping this weekend. It looks like the tank collar cracked slightly where the drain valve screws in. Its only dripping once per 6 seconds or so... so fairly slow. 

I'm wondering if anyone has repaired Polyethylene? Its a fairly difficult surface to get most things to stick to.

ATM, I was thinking about just removing the drain, putting a hose clamp around the collar to prevent further cracking and close up the existing crack some, smearing the bejezus out of the valve threads with quality silicone and sticking it back in (not as firmly / deeply of course, tapered threads would put additional stress on the collar). 

It's not a stressed area and with the crack as small as it is (as noted by the fairly slow drip), I think it will work well enough. Or is there something better I should look into?


-DallanC


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## Don K (Mar 27, 2016)

You may want to look into someone in that area that can weld it. My buddy has a plastic welder and hes repaired all kinds of plastic, including Polyethylene. I never knew that stuff can be welded but hes fixed all kinds of things and its turned out great. Not sure if there's enough room to get at it or not.


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## Critter (Mar 20, 2010)

Harbor Freight has a couple of plastic welders for a DIY. 



Before attempting it I think that I would try and find a scrap piece and practice on it.


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## BPturkeys (Sep 13, 2007)

These guys...Nyle...weld polyethylene and would probably run a little bead along there for pretty cheep.
http://braunandco.com/


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## DallanC (Jan 13, 2009)

Welding just by itself probably wont work due to the threads getting warped or melted entirely.


Looking closer at it tonight, it looks like only the "spinweld" fitting has cracked, the tank is good. Some googling shows you can cut old ones off and weld on a new one. 


The fitting is $3 and the driver for the fitting is $240 -O,--O,--O,--O,--O,--O,--O,-



Sooooo as a temporary fix I did put a hose clamp around the collar and liberally coated everything with silicone and reassembled. I'll do a pressure test tomorrow when its all dried / cured. Should get me by for a short time until I get a proper fix.



I will call some RV dealers and find someone who does these repairs and see how much it will cost to fix. Thanks all.


-DallanC


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## phantom (Sep 13, 2007)

I don't know if it's the same, but I had a leaky outboard gas tank, I got some two part plastic weld at Checker auto, has not leaked again.


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## gdog (Sep 13, 2007)

I battled with a leaking fresh water tank on my toyhauler. Found a guy in SLC who builds custom plastic water tanks and had him "weld" the crack. He told me up front not to expect it to hold forever, that welds on those type of tanks just don't hold up. It lasted one season and then the weld gave out. Mine was on the bottom of the tank. I sold the trailer (full disclosure of leak) and the guy ended up having to replace the tank.


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## DallanC (Jan 13, 2009)

phantom said:


> I don't know if it's the same, but I had a leaky outboard gas tank, I got some two part plastic weld at Checker auto, has not leaked again.


Yep that stuff is great for most tanks... but it doesn't stick to Polyethylene.

-DallanC


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## DallanC (Jan 13, 2009)

gdog said:


> I battled with a leaking fresh water tank on my toyhauler. Found a guy in SLC who builds custom plastic water tanks and had him "weld" the crack. He told me up front not to expect it to hold forever, that welds on those type of tanks just don't hold up. It lasted one season and then the weld gave out. Mine was on the bottom of the tank. I sold the trailer (full disclosure of leak) and the guy ended up having to replace the tank.


Yes I read that from a tank MFG website, heating to weld cracks weakens the molecular structure of the plastic. If its in a higher stress area it will crack again for sure.

The spinweld fittings are a bit more unique and safe to replace as they generally are only in unstressed areas.

-DallanC


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## DallanC (Jan 13, 2009)

Called 6 different RV dealers, 5 went to voicemail and none bothered to call me back. The 6th, General RV at point of the mountain answered and were friendly, they estimated about $200 for someone to spinweld on a new $3 fitting. -O,-

In other news, my $0.50 hose clamp + lots of silicon is holding up great. I think I'll roll with that for a while.


-DallanC


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## Critter (Mar 20, 2010)

And in the meantime you can keep your eye out to see if you can find a replacement at a decent price.


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## DallanC (Jan 13, 2009)

Critter said:


> And in the meantime you can keep your eye out to see if you can find a replacement at a decent price.


Yep. The fitting is literally less than $3, the spinweld tool is about $70 but they seem to be sold out everywhere I can see. It fits in a router and it friction melts against the tank. Youtube videos show it only takes a few seconds of spin to get a good melt / weld.

I'll wait for the tools to come back in stock, order one and just weld it myself, then sell the tool on ebay after wards. Even if I had to eat the entire cost of the tool, its still well below what a dealer charges or even a new tank.

There are some mobile RV repair guys listed that may do these types of repairs cheaper I plan on calling. I'm not in a rush as you say, so I can look around for a decent price to repair it. Its been a great cheap camp trailer.

This really shouldnt be more than a $50 repair... the tank is fully exposed and the fitting is right there in the open. Maybe I'll pull the tank when its time to winterize, and find a RV shop or plastics shop mid winter that needs work.

-DallanC


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