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fuel sending unit nuts striped???

copout@castaways[email protected] Posts: 5,779 Admiral
appears that I did not have a leak in my sending unit I just had a loose seal. :banghead
thankfully chuddybuckrivet hooked me up with a wholesale price & I now have an extra sending unit but I now have a different dilema.

two of the five holes are striped & removing the aluminum tank is a PITA!

what are my options? larger self tapping screws? I thought of some how securing nuts on the inside of the tank so I could screw though the original holes & into the nuts but not sure how I'd secure them. would JB weld be an option for aluminum?



  • ChuddybuckrivetChuddybuckrivet Posts: 3,156 Officer
    Ouch that's a bummer pal.

    JB weld will stick to cleaned and scuffed aluminum but I dont know how you'll JB weld the nuts to the underside without getting
    some of the epoxy into the threads of the nuts, which then the screws wouldnt go in.

    Maybe tap new threads the next size up? Harbor Freight has tap and die sets fairly cheap.
    That would involve having to drill out the sender holes larger too. I would think larger self tappers
    would work too, but may be more prone to leaking around the screw holes. I dunno....
  • copout@castaways[email protected] Posts: 5,779 Admiral
    if I were to do that whats to keep the next size from striping? I'd like more threads to tight down against the gasket.
  • 9-Lives9-Lives Posts: 2,124 Captain
    It may not be the proper way but I used a larger self tapping screw on one of my tank's senders. It worked and it's been that way for over 10 years.
  • ChuddybuckrivetChuddybuckrivet Posts: 3,156 Officer
    It probably stripped due to corrosion between the aluminum tank and the SS screws. Whatever route you go, use Tef-gel when you put the screws back in there.

    I hear ya though, if you tap up and those do strip too, then next thing you know you got 3/8" bolts holding your sender down. :idiot
  • SCFD rtrd.SCFD rtrd. Posts: 1,390 Officer
    Can you have the tank pumped, then have a 1/4" aluminum ring welded over the existing hole. That would give you a new 1/4" thick piece of metal to drill and tap. Or maybe replace the stripped-out holes with stainless threaded inserts.
  • SCFD rtrd.SCFD rtrd. Posts: 1,390 Officer
    Sorry, double-tap
  • copout@castaways[email protected] Posts: 5,779 Admiral
    I can remove the fuel & then remove the tank but it's a royal pain & would be a last resort.

    Is there a fitting I could drill out a hole then jb weld in from the top. Kinda like a slip outer with a threaded inner that has a profile of a T?

    Keep the ideas coming...
  • drkpttdrkptt Posts: 1,927 Captain
    If the aluminum is thick enough, tapping for the next size screw should do the job. But the rule of thumb for tapped holes is a minimum threaded length equal to the bolt diameter.

    Another fix would be to slightly overdrill the stripped holes in the tank, to the same diameter as the clearance holes in the sending unit flange. Insert screws from the inside of the tank (assuming the hole for the sending unit is big enough to get your fingers into) with epoxy (JB Weld) under the screw heads. Now you've got studs sticking out. After positioning sending unit put three nuts on each stud (stay with me here). Jam the top two nuts together by tightening with two wrenches, then hold the jammed nut pair with one wrench while tightening the nut against the sending unit flange. Remove the jam pair. This keeps you from breaking the JB Weld loose.

    Third choice: Threadsetter Rivet Tool.
  • copout@castaways[email protected] Posts: 5,779 Admiral
    thank you!!!
    I think what I'll try is to invert the whole thing first. There is enough thread left that I can try to thread screws in from botttom out then just secure with nuts from the outside. Only down side I see wopuld be when the time coe=mes to remove them.... Still thinking here
  • EggsuckindogEggsuckindog Posts: 1,526 Captain
    drkptt's idea is a good one, although just using self tapping screws I think would be fine - it doesn't need to be that tight - you can not use sealer on the gasket it will stay googy and drip in the tank. When I switched mine the screws supplied with the sender were a different thread, I figured it out before I stripped them and used the old ones - thats how it probably happened.

    personally I would use the screws - I love JB though- but would not want the the screws failing in if I ever took it out and they had come loose
    1976 SeaCraft master Angler - Merc 200 XRi
  • SCFD rtrd.SCFD rtrd. Posts: 1,390 Officer
    DRKPTT is a genius. That's the coolest thing I've ever heard.
  • ChuddybuckrivetChuddybuckrivet Posts: 3,156 Officer
    SCFD rtrd. wrote: »
    DRKPTT is a genius. That's the coolest thing I've ever heard.

    Agreed. I hate cliches but that's thinking outside the box!
  • copout@castaways[email protected] Posts: 5,779 Admiral
    Agreed. I hate cliches but that's thinking outside the box!
  • MGDMGD Posts: 1,212 Officer
    If you do drill/tap that be VERY careful about the shavings getting down in the tank and clogging your pickup
  • FS DanFS Dan Posts: 2,353 Moderator
    a couple thoughts/ tips

    when using a tap, dipp the tap into some grease, it will help capture the shavings and keep them from getting into the tank.

    The poprivet threads are pretty cool, lots of applications where it would be useful. This may not be one of those times. In looking at the final results, the flange on the rivet sticks up from the surface. this will make sealing the sending unit problematic. especially if you only use it for a couple of the mounting bolts.

    I like the bolts/studs from underneath idea. As long as there is enough clearance for the sending unit to go in. On some boats the access to the sender may not line up directly with the sending unit(below deck tanks), studs will require even more clearance.

    Formerly Catmandew
  • copout@castaways[email protected] Posts: 5,779 Admiral
    I've got clearance. This thread has been very helpful. Thanks to all that have offered help. I'll post some pics later this week when I get to work on it.
  • Tom FoleyTom Foley Posts: 111 Officer
    Obviously be extremely careful working around that tank opening , no electric drills cordless or 110 V , static electricity , cell phones etc . Some may scoff at the static electricity deal but the danger is real ! If you are not going to remove the tank for a proper fit , using the next size self tapping or self drilling screw will yield good results used with a new gasket . Sender flange hole size will have to be increased to accomodate the larger screws ( # 12 ) This is the reason we always have a doubler welded on the inside of our tanks in the sender area giving a full .250" thickness to tap into for the usual 10-32 or 10 - 24 threads .

    Small chips will be contained in the primary filter/ seperator and should be changed after your first trip imo .

    Marine Specialties Custom Fabricators


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