Lining Fiberglass Tanks

[rev. victor]

I have a 73 Ossa MAR that I am freshening up for some vintage action. Currently the tank on the bike leaks rather badly and i am trying to do a little research as to the best method of sealing it. I've had look luck with pour sealers like Kreem and POR15 on metal tanks but this is my first dealing with a fiberglass tank. So my questions are:

1. Do the standard pour in style sealer work with fiberglass?

2. If not, what should I use?

3. What is the best way to remove all traces of premix before treating? MEK or something else.

Thanks for the input and suggestions.

Edited February 18, 2005 by Rev. Victor

[charliechitlins]

I've seen LOTS of bad Kreem. Comes off in sheets and wraps itself around the petcock. Maybe bad prep on the part of the owner. I've never used it myself.

Gotten good reports on POR-15.

I use something called Randolph sloshing sealer. Available at some airports and most aircraft supply places (Aircraft Spruce, etc).

Although I haven't tried it on fiberglass, I'm told it works fine. The directions call for Acetone or MEK; both of which shold be fine for fiberglass.

It will soon be in my 247 Cota tank, so I'll know for sure.

It's very thin, though. I don't know about using it on a tank that leaks badly.

I think the POR 15 might be thicker.

[woody]

Have a look on Mats Nyberg's Ossa site, link below. At the bottom of the homepage is a list of specialists etc. One of these is Jeff Nolen of Vintage Dirt Bike in Texas - handy if you are in the US. They specialise in repairing fibreglass tanks so may be willing to give some advice.

http://hem.passagen.se/ossa/

The website for them is www.vintagedirtbike.com but it doesn't seem to be working at the moment.

[bullfrog]

While I have no personal experience with Ossa tanks, if they are at all like vintage Bultaco tanks the ONLY thing that kept the gasoline on the inside was the gel-coat. So it is possible that the tank is not structurally damaged (of course it MAY be). Bultaco restorers have all kinds of procedures for sealing up 'taco tanks. Almost all of them recommend acetone rinses to remove pre-mix residue.

Ed

[rev. victor]

Thanks for all the tips. The tank appears to sound but leak more fuel than a little weeping at the seams. I will probably try a lining, if that fails I guess a call to Sammy M is in order.

[woody]

Just so that you know (apologies if you do already) the tanks sold by Miller are based on the shape of the UK alloy tank used on the MK2 onwards, therefore different from your MK1 fibreglass tank. Not a problem in terms of fit as they both use the same fittings, just something to think of in case you want to keep the look of the MK1 tank.

He used to make the tanks in both alloy and fibreglass, about

[rev. victor]

The look of the MK2 would be fine. I am intent on this machine being a rider not a museum piece. An alloy tank would look very nice as I have never seen one in the US.

[pa.]

I would go with the cleaning the tank with Acetone first.

Use a Flow Coat Gelcoat as normal Gelcoat will not cure. Put an amount of the Gelcoat into the tank and the roll the tank around to cover the inside.

The Fibreglass will allow the passage of liquids so the only thing to stop the fuel from leaking is the Gelcoat. Certain Epoxies will also do the job, just make sure it will not react with the fuel and will stick to the tank interior.