Aluminium Fuel tank pitting

Discussion in 'Boats, Motors, Trailers and Towing Rigs Forum' started by gungadin, May 2, 2019.

  1. gungadin

    gungadin Well-Known Member

    Working on an aluminium fuel tank. Replacing a fuel level gauge. due to gasoline smell when full. Definitely leaking there, small hole on top of sending unit. Cleaned up the area where the sender sits with a bristle brush, quite a few pits in the tank around where the sender sits, no holes and it looks like electrolysis pitting. Nowhere near through the aluminium, so I want to fill it level in situ before installing the new gauge. Any ideas on the best filler would be appreciated, but no welding please.:eek:
  2. ryanb

    ryanb Well-Known Member

    Epoxy then sanded flat has worked well for me in the past...not sure if this is the best...or even good, but I haven't seen any negative effects.
  3. wishiniwasfishin1

    wishiniwasfishin1 Well-Known Member

    JB Weld would likely do the tick.
  4. Mudshark

    Mudshark Active Member

    Jb weld for sure
  5. macro

    macro Active Member

    Not jb weld. Not some random epoxy. I went through this when I epoxyed a fuel tank. You used to be able to do this, because epoxy is gasoline safe. Epoxy not however ethanol safe. Dont believe me? Coat a screw in epoxy and float it in gas for a few days.. it will go soft. I ended up uaing hysol E-120hp. Not cheap, but wont get attacked by ethanol. Good luck
  6. wolf

    wolf Well-Known Member

    I used JB weld in past lasted over 10 years before i had to do some DOT upgrades so had that part cut out or another product for gas is called Seal-all ive used it alot for bush fixes
  7. Rockfish

    Rockfish Well-Known Member

    x2 on Seal- all for temp. repairs. It is formulated for metal gas tank leaks. We used it on some pin hole leaks before we replaced our Al tank.
  8. If the pin holes where the sender sits do no go all the way through, JB Weld should be fine. There will a gasket under the sender and fuel should not reach your repair. The prep work is key here. Can you get to the area with a drill motor with a wire brush installed? If not how about a Dremel tool with a wire brush? Get as much of the corrosion out as possible. Clean the area real well afterwards. One of the best general purpose cleaners out there is brake cleaner. You will find it at all auto parts stores. The reason it works so well is when it dries there is no film left behind. Scrub out the area real well using an old tooth brush and brake cleaner
  9. Rockfish

    Rockfish Well-Known Member

    I would be dam careful with open armature power tools (lots of sparks) doing repairs on a tank with gas/vapor in it. Especially if the pits are deep and you are grinding into them or the seal on the sender is failing as a result of corrosion under it and leaking vapor, especially if you can smell or see fuel residue there. With marked marine gas it looks like a redish stain when the volatile components have evaporated out of it. When we cleaned out the pin hole leak and the surrounding area in the top of the tank to remove the white Al oxide before sealing we used only hand tools, mild abrasives and Al cleaners and a small cone grinding stone in a hand holder tool for deep in the small hole. Even then we were very gentle with slow movement, but we were dealing with obvious exposed gas and vapor. We also discharged/grounded for static.
    Last edited: May 3, 2019
    Prfisher and macro like this.
  10. Aces

    Aces Well-Known Member

    That’s just putting a band aid on a serious wound.

    Possibly the start of more and worse problems on one of the most dangerous parts in a boat. If it was me I would replace the tank
    turbomack likes this.
  11. gungadin

    gungadin Well-Known Member

    Thanks for all the advice and help on this one. I cleaned up the area really well and used plenty of brake clean. Couldn't find that E-120hp, so decided to use JB weld marine epoxy, let it partially set up for 15 minutes before tightening down the screws holding down the sending unit. Some squeezed out so I filleted it around the sender. Looks fine and all the holes are filled to the good metal.

    I certainly would not consider it a serious wound that would in anyway necessitate a tank replacement. IMO the pitting was caused by salt water on top of the old sending unit in the proximity of the electrical connector for the fuel sender. The connector and the sending unit are now covered with plasti- coat which should prevent that reoccurring.
  12. wolf

    wolf Well-Known Member

    there also should be a grounding strap beside sending unite so the tank is grounded... make sure that is hooked up or make one..
    gungadin likes this.
  13. gungadin

    gungadin Well-Known Member

    Yes there was two black wire 16 ga. grounding wires in the same crimped connector, that were attached to a small tab that also has the serial number of the tank on it. The tab is welded to the tank. Obviously one is for the sender, but after your suggestion I am going to separate them, just to make sure that both are connected to a ground, and not just the sender with the other one piggybacked to it. The boat is at least 20 years old, but seems solid. Thank you for the heads up.:)
  14. wolf

    wolf Well-Known Member

    Right on, as a old timer said to me once you can never have enough ground wired on a boat..... LOL
    he even would ground certain bolts on his boat. sounds like you have it all looked after good job man

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