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Thread: Tank sealer

  1. #1
    New Member trevor9's Avatar
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    Tank sealer

    I have a fibre glass fuel tank on my SSDR and want to ensure that it is ethanol resistant by using a pour in sealer. Any recommendations from those who have been, or are in, a similar position
    thanks


  2. #2
    Captain Dave Morton's Avatar
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    Had the same dilemma when building as not all sealants like Kreem for example are compatible with either fibreglass or plastic tanks and also the fuel lines or any other vunerable carb parts wouldn't have been protected by a tank sealer.
    In the end I decided to just use the super unleaded fuels as there was less chance of any ethanol to be present according to BP UK and would also test for ethanol (plenty of You tube videos)


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    Co-Pilot Arielarts's Avatar
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    Be careful of sealers, they can make matters much worse by not completely adhereing and bits flaking off. Also, some are still degraded by ethanol, in spite of claims to the contrary. In my research on this, I found that some true epoxies are affected by ethanol, but polyester resins usually are not (even the LAA believe this if you look at their MOGAS approval requirements). Polyester is the cheaper option, and tank builders often use it in place of epoxy. I did a test on our glassfibre tank by gluing a temporary alloy pocket on the side and leaving 5% ethanol fuel in it (with top-ups) for several weeks. Then checking for any softening of the surface gel coat.


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    Co-Pilot Peter Twissell's Avatar
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    I have used sealers in motorcycle tanks on several occasions over the last 10 years. I get the kits from Caswell http://www.caswelleurope.co.uk/, mainly because I was already using them for plating kits.
    So far, I have not had any problems with the tanks I have sealed. Most applications have been on older bikes, which are often parked over the winter.
    As Dave says, the sealer won't protect the fuel taps, pumps, pipes or carb, but those parts are generally easier and cheaper to replace than the tank.

    Not to be confused with sealer issues, I have seen a translucent jelly build up to the point that the fuel tap was blocked. On further investigation, I found that the jelly is in fact a bacterial growth which can occur in the water/ethanol mix which develops when the system is left undisturbed for some time. The bacteria grow all the time, but with regular use are flushed through the system. It is the excreta of the bacteria which corrodes copper and zinc based parts.
    DO NOT start adding antibiotics to your fuel...!
    G-BZNP Still not dead


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    Co-Pilot goldrush's Avatar
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    Quote Originally Posted by Peter Twissell View Post
    ..snip..

    Not to be confused with sealer issues, I have seen a translucent jelly build up to the point that the fuel tap was blocked. On further investigation, I found that the jelly is in fact a bacterial growth which can occur in the water/ethanol mix which develops when the system is left undisturbed for some time. The bacteria grow all the time, but with regular use are flushed through the system. It is the excreta of the bacteria which corrodes copper and zinc based parts.
    DO NOT start adding antibiotics to your fuel...!

    Apologies if a bit of a thread drift, but following on from Peter's point regarding bacterial growth due to Ethanol, the following pictures from memory, were obtained from Conrad Beale and also an accident report. (the fuel colour was not due to additives/2stoke)
    Evidence appears to suggest that the growth is more prominent in glass filters than plastic ones
    They may just concentrate the mind.
    Attached Images Attached Images
    Last edited by goldrush; 17-11-17 at 16:11 PM.
    Wally Hayward


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    Co-Pilot BobH's Avatar
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    Fuel filters

    There is a quick way to ensure that the bacteria doesn't clog the filters. Replace the fuel filter(s) on a regular basis, say once every 6 months. I've just bought a whole batch of plastic ones that have folded paper filters in them. They are large capacity filters, and cost something like 5 for 10. In fact I've just ordered a new batch of 20 for 8.50, and here's the link to the advert on Ebay.

    https://www.ebay.co.uk/itm/20-x-Univ...53.m2749.l2649

    It struck me that these things will stop bits of flaking fuel tube as well as anything else, but after 6 months or so it's probably best to replace them before the gunge can build up and block them. At the prices I've quoted above, it makes sense to do that rather than using expensive metal and glass filters that look pretty, but clog.


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    New Member trevor9's Avatar
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    Thanks for the comments. As ever it does not seem a simple problem and although Caswell sealer looks like it might do the job there is a large baffle in the tank which will complicate the preparation and the flow of the sealer round the tank.
    But the tank looks like it is molded in two parts, the upper part being like a lid.So it gives me the possible option of cutting the tank along the join, Having good access to clean and prep the inside, paint on the sealer and then join the half's back together.
    An ethanol resistant tank is available but is a lot smaller in capacity than I have at present. So I have options, just got to choose one and as the rain is beating down on the windows there is no hurry!


  8. #8
    Co-Pilot Peter Twissell's Avatar
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    The baffle shouldn't be a problem. Motorcycle tanks often have a large 'tunnel' where they sit over the frame. The technique is to pour in the resin, close the filler neck and then turn the tank over in every direction continuously for about 20 minutes to ensure that the resin has coated the entire surface.
    G-BZNP Still not dead


  9. #9
    Co-Pilot Randombloke's Avatar
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    Quote Originally Posted by BobH View Post
    There is a quick way to ensure that the bacteria doesn't clog the filters. Replace the fuel filter(s) on a regular basis, say once every 6 months. I've just bought a whole batch of plastic ones that have folded paper filters in them. They are large capacity filters, and cost something like 5 for 10.
    My inspector gave me a good reason for not using paper filters, but I've forgotten what it is. He suggested Nylon, so I use the Skydrive offered filters - http://www.skydrive.co.uk/proddetail...d=SKY29&cat=40

    I'm wary about too large a filter that traps too much air, as air is a good "spring" and will damp out pulses of fuel pressure rather than pass them on, as an incompressible fluid does...

    Quote Originally Posted by BobH View Post
    At the prices I've quoted above, it makes sense to do that rather than using expensive metal and glass filters that look pretty, but clog.
    As Paul Dewhurst has correctly pointed out in the past, the reason for the expensive glass or metal fuel filters is because they are fire resistant, which is a requirement for permit aircraft if it's in the engine bay. Compare a Blade and a Quantum. All in the location of the fuel filter, just outside the "engine bay" on a Quantum, well inside on a Blade.
    Steve U.
    PG, HG & microlights
    "Weekend bimbler, day to day car driver & genuinely undeserving Southern oik who has never done anything of any worth"


  10. #10
    Co-Pilot Arielarts's Avatar
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    Bob, I'd seriously avoid paper filters. They were generally regarded as a 'don't do' after a series of fuel starvation engine failures back in the 90s. If you look on the net for filters with 0.3mm (smallest orifice in the Bing carb) gauze, that's best. I found a type years ago that Mercedes use that were legended with 0.3mm.


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