Leaking FIberglass Tank

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Dec 27, 2005
I have recently resprayed my tank and the other day i filled my tank up with fuel and discovered there is a small leak were it wraps around the front stem so it is not were the paint is and was wondering how a go about repairing it or is there a sealer that goes on from the inside that i could use to seal the tank?

All help will be appreciated
Repairing fuel tank

My large Interstate fiberglass tank was weeping at the rear bottom and I reparied it using the PRP POR-15 product. Look at www.prp-porstore.com. These guys are in Indiana, phone: 001-219-531-0929. I'm sure their website will show distributor information.

I followed the directions very carefully, first using the stripper to be sure any previous sealant material is removed. Following stripping and hot water rinsing the next step is with "Marine Clean" mixed with very hot water with some old nuts and bolts, shake around, rinse, etc. After rinsing you want to be certain that the inside is TOTALLY dry and I used a hot air gun and rotated the tank all around while blowing inside. If the tank is metal there is another step with included chemical. At each phase I pitched the stuff into a corner of the garden and no weeds are growing anymore. I'm certain these materials are capable of genetic changes in humans! Finally the Sealer is poured in and the tank rotated to ensure coating all surface, especially the "corners". This entire process took about half a day, including moving the tank around periodically during the drying phase. I gave it a couple days for the coating to really set - and no more leaks. I'm confident that this sealant remains slightly flexible to prevent any future problems.

Stuart Ostroff
It has been a few years since I used it, and there may be newer varieties, but there is a pour in coating system called Kreem (I think). I think it was developed for steel tanks, but should work. The kit has multiple bottles in it, one of which is a cleaner/etcher that probably shouldn't go into a 'glass tank. Hint: Read the instructions carefully! ALSO, remove the petcocks, and plug the fittings. Moving on, grab a clean bath towel or small blanket to lay the tank on. What you need is to be able to set the tank so each inner surface is level at some point. Bunching up the cloth or adding more rags, etc. The process is to pour in the heavy liquid, slowly rotate/tilt the tank to coat all surfaces and then lay it down for the specified time. You then repeat, but lay it down with the sealer sitting on a different surface. This continues until you run out of liquid sealer, or liquid refreshment. :) You did remember to coat the area that leaks, yes? The problem with 'glass tanks is the defect on the inside may not be directly opposite the external leak. So, if you decide to do a repair, the patch should be larger than the visible damage. BTW, with a 'glass tank, if the leak is a crack near the mounts or petcocks, it should be patched first. Otherwise, the crack will continue to travel. You can then seal it, for a belt and suspenders approach :wink:
I bought the POR-15 motorcycle tank repair kit and the instructions read "if using on a fiberglass tank call before using" why is this and what steps did you take that are different from the instructions supplied, the instructions also say "do not use the filler hole" is that more directed at car fuel tanks. One more thing will the metal ready work as a etch primer on chrome so i can paint it.
Been there done that. My tank was cracked in the same place when I bought the bike. I patched the leak myself with a "Bondo" fibreglass repair kit then had the tank lined. I didn't feel like dealing with the toxic chemicals myself so I sent the tank out to a guy in California. No leaks since, and that was two years ago.

You might check out Caswell Plating's epoxy tank liner. I hear good things about it...

Jota said:
Enquiring minds would like to know: is the tank steel or fibreglass?

= See thread title (Leaking FIberglass Tank).
well debby i cant say that was much help as all you did was tell me to buy a differnet product. To anyone else who has used the POR-15 U.S Standard tank sealer on fiberglass tank can you please give me your advice on how i should go about doing it and what precautions i should take when doing it to fiberglass.

Just comments, feel free to ignore them :!:

I'm just a dumb girl, but looks to me like Stuart's instructions above were pretty detailed. Maybe you didn't see that post :?:

Good luck with the bike.

After using the POR-15 tank sealer i find my self never using it again as i have followed there instructions but cannot possibly see well enough inside the tank to make sure there are no puddles forming i have done my best to get rid of all the excess selaer but can still see it puddling in the front corner directly under the cap wich it will most likely be doing on the other side. is this a mojor problem and will this stuff still cure or will every last drop of excess need to be removed??? Please Help
why not call the manufactor of the product themselves. some here may have experiance, but it would probably be the best thing to call them directly and ask.

that way you can be sure that your doing it right and that any issues (if there are any) are taken care of before you put fuel in it and go for a ride
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