Help I can not find the Fibreglass tank melting post

I tried the search feature but I had no success . I am trying to find the post on a fibreglass tank melting, it had a picture that showed down the inlet ports and looked just like mine. I wiped the gunk out of the ports while it was still hot and it wiped out ok. The paper towel I used turned a purple colour and black muck. My tank is green so I guess it came from there. The tank felt sticky around the filler cap where it is bonded to the tank and that was before I put any fuel in after sitting for about 18 months. Removed the fuel from the tank and the fuel taps, left the fuel cap open to dry while I played with the carbys, another story. The inlet manifolds had a brown colour stain, I removed them to clean them and the carbys were stripped at the same time. No more muck in the carbys in the short time that I ran the bike than when I fitted them. I think the brown stain was there when I fitted the manifolds as the high spots were still shiny. I did not remove all the impefections as I have read somwhere not to try and open up the ports to much plus a little turbulence helps the mixture.
Ian

I have had good reports on POR-15 and that is what I will be using on my tank. Check out different fuel brands, they don't all have the same additives and they don't all eat fibreglass tanks. Here in Montreal Canada, I found that Petro Canada fuel will go right through my Fastback tank in a single tankful, Esso on the other hand has no adverse effects (yet).

Jean

Jeandr said:

I have had good reports on POR-15 and that is what I will be using on my tank. Check out different fuel brands, they don't all have the same additives and they don't all eat fibreglass tanks. Here in Montreal Canada, I found that Petro Canada fuel will go right through my Fastback tank in a single tankful, Esso on the other hand has no adverse effects (yet).

Jean

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I did not like POR15 on fiberglass. I'd much rather use the Caswells.

swooshdave said:

Jeandr said:

I have had good reports on POR-15 and that is what I will be using on my tank. Check out different fuel brands, they don't all have the same additives and they don't all eat fibreglass tanks. Here in Montreal Canada, I found that Petro Canada fuel will go right through my Fastback tank in a single tankful, Esso on the other hand has no adverse effects (yet).

Jean

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I did not like POR15 on fiberglass. I'd much rather use the Caswells.

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Why is that? (it's not too late for me, I haven't done it yet)

Jean

My Tank Sealing

I've had multiple leaks after POR15 on two tanks I did, I have to drain the tanks if I know it's going to sit for more than a couple days.

With the Caswell-lined tank I have, no problems.

POR15 themselves state that it should not be used on fiberglass.

At lot if it depends on the prep and technique for applying the coating, perhaps I didn't do it "right" enough. Or maybe I did. :|

The Bultacos are off-road and a little leak won't do too much damage (except for ask me sometime about the waterfall of gas before a race sometime...) but on a road bike, no way would I trust a POR15 fiberglass tank too far from home (end of driveway... :? )

Maybe people have had better luck than I with POR15 and fiberglass, but I haven't found too many of them.

It's the ethonal in US. fuel that causes the probblems. I have a fiberglass Interstate tank that has been on my MKIII for 20 years, it was ok till about 2/3 years ago, when the slides started sticking, I finally figured it out what was happening. The Caswell product seems to have cured the probblem for now. I also have a Ducati Multistrada that has a plastic fuel tank that is growing, Ducati has agreed to replace it under warranty. BMW, Moto Guzzi, and KTM has had probblems with plastic fuel tanks because of Ethonal in the fuel. The plastic floats in carburettors crack and leak, fuel lines get gummy, so do the rubbers in fuel valves. It's not just the relics that are having probblems.

Ken G.

Hello, regarding your fibreglass tank. POR15 Tank Sealer should NOT be used in fibreglass tanks.
I made the mistake of using POR15 in a new Ducati TT2 fibreglass tank. After the first fill of fuel (no ethanole) the POR15 came loose like a big plastic bag inside the tank, then the exposed fibreglass went sticky. The bits of POR15 left inside the tank were imposible to remove, thus I couldn't re line the tank with a better product. I had to cut the bottom out of the tank to remove the bits I couldn't reach through the filler cap hole.
I ended up using a product called Hirsch Auto Tank Sealer. Looks and smells like Kreem.
12 months on and all is still good.
Hope this helps.
Regards Graeme.

I was thinking of useing Por15 but reading on their site did not convince me it was the way to go. I will read up on the Hirsch Auto Tank sealer GRM450, sounds like the way to go with your results. I appreciate all of your experiance and your results. I will do a bit more research before I commit to a product as I do not want to have to cut it open to remove what I use if at does not work.
Thanks to all Ian.

Hello Scruff, I see you're in Australia. If this is any help, I spoke to several people about lining a fibreglass tank due the fuel additives that disolve fibreglass. The chap who I buy my fibreglass resins from suggested lining my tank with a certain resin that is made for fuels, apparently it's used in making ocean racing boats due to it's strength. (all this is after I'd used POR15)
But the tank had to be washed with warm soapy water, rinsed,dryed for several days, then rinsed with acetone, before the new resin was added.
Another fellow I know repaires old Bultaco fuel tanks. He swears by Hirsch Auto sealer as he has never had a problem with it.
He does these repaires on a semi profesional base, so he sees some pretty horrid old tanks. I don't know if it is imported to OZ by anyone else. I can supply his number if you need, just contact me. The tank prep is pretty much the same as previous.

Regards Graeme.

I have never used POR-15 on fiberglass, but I have used Caswell. Having worked in polymer chemistry for 35 years, much of it with epoxies, the superior adhesion and compatiblility with the polyester resins in fiberglass give it the edge.

I have steel tanks lined with both POR-15 and RedKote that are fine, but I won't use either on fiberglass. I picked up a very nice reproduction fiberglass Fastback tank quite cheap that was coated with POR-15. It looks like it was coated before putting it into service, but coating is coming off in sheets. I have no idea what prep work was done prior to coating, but that is absolutely key no matter coating what you choose.

at some point in it's life, my tank went down and there was a crack in it: I thought I had repaired it until around thanksgiving when I put the first tanek of fuel in it, only to find it getting progressively leakier:

I used the Caswell sealer on my tank: there's been gas in it for about 3 weeks and everything seems to have cured all the leaks,weeps, etc. i know it's early in the game but when I did a search of feedback on tank sealers, the overwhelming majority of folks seemed to prefer the Caswell, so that's what I went with......(and no goop in the carby's)

so far so good!

kfh