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Stripped and leaking fuel sending unit

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Stripped and leaking fuel sending unit

Old 01-26-2019, 11:16 AM
  #21  
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I did this exact fix 4 years ago and the 5200 is not soft. I turned the sender and drilled 5 new holes in the poly with a ratcheting screwdriver. I didn't drill through the tank, the poly was real thick around the hoIe. I put 5200 in the holes and put selftapping stainless screws in. I put 5200 under the gasket and then all around the sender.
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Old 01-26-2019, 11:22 AM
  #22  
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Yes if you can get it almost but not quite tight enough or are replacing with redrilled screw holes etc., you can most definitely use permatex #2.

Apply it liberally, it works because this variation of it never really "hardens" so it can take the boat vibrations and won't just start leaking again.

And for those who said no because it has to be for gas and aviation use. Just read the label before you slam someones suggestion.

https://shop.advanceautoparts.com/p/...E&gclsrc=aw.ds
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Old 01-26-2019, 02:25 PM
  #23  
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Here's what I did once that worked well.

Split ring is needed. Butter it up with permatex and screw the bolts from the under side.. Since the holes are extra large it will easily allow the bolts to pass and now you have studs. Don't over tighten. It doesn't take a gorilla seal. Screw on a nut just to make sure it doesn't fall but the permatex is pretty sticky anyway. Snug it up and then you can remove the nuts and install the gasket. Again a bead of Permatex to make sure there are no gaps. From then on you just remove the nuts to service the sender. They should have done this in the first place or at least added a heavier aluminum for the sender area.
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Old 01-26-2019, 03:32 PM
  #24  
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Originally Posted by catch232 View Post
Read post #6.
Right you are, Catch22.
. The split ring you so wisely mention in #6 is IMO the right way to go about this repair for correct snug seal without the sealer on the gasket to cause more problems later. It was made to addess the problem.
The split ring allows more-snugly tightening the screws into it's threaded holes because it is stronger and likely thicker than the tank aluminum. Often used with a cork "gasket" between split ring and underside of the tank hole to separate steel from alu. I believe, and proper adhesive , not 5200, holding it in place permanantly . This makes it better/stronger than the original installation.
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Old 01-27-2019, 07:40 AM
  #25  
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Originally Posted by slickster View Post
5200
Not sure I would use 5200 for too much on a boat specially if you need to replace something like a sending unit. If it ever has a problem you will have a real hard time taking it off again.
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Old 01-27-2019, 04:56 PM
  #26  
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Originally Posted by Jonnyu View Post
So I replaced my broken sending unit. It was a pain to get to as the access hatch is 5 off. So you only can see the sending unit at a angle. 2 of the 5 bolts where stripped out and the hole of the tripped out bolts took a 5/16 tap. I was able to tighten the two stripped ones a little but I couldnt crank down on them in fear of stripping it again. After taking the boat out a couple times I noticed I still have fuel seeping around the sender. So the question is is there any sealant I can use to install the sender unit? I was thinking of pulling sender and installing it wet sealant and installing the bolts wet with sealant on threads. Is there a sealant I can buy locally in south Florida? Or any other way of fixing the tank? I have only about 2 of space between the deck and the top of the tank.



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Old 01-27-2019, 05:36 PM
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Okay Lots of ideas. Im thinking of using the split ring. Tank has rivnuts so I will have to remove the working ones to install the split ring. I found this company is down the street from me.
Stainless Steel Underring (for SSS & SSL sensors)

this will work. If I dont remove the working rivnuts Im going to seal the send with PRC 890. This is what we use to Seal tanks in aircraft. If anyone is looking for some you can pick up at aviall. Just remember to spray mold release if not you will have a hell of a time removing it. On aircraft we shoot a dab of sealant into the screw hole and thread screw in. If you buy some to repair your tank buy 890-B2 as it kicks in 2hrs. B1/2 only has working time of 30 min. I will update post once Im done. Im going to go ahead and replace the other sender on my other tank. This way I dont have to deal with it again. (Hopefully)
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Old 01-27-2019, 05:38 PM
  #28  
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Here is Specs on 890

Fuel Tank / Proven Standards

P/S 890 Class B Fuel Tank Sealant

P/S Class B is an aircraft integral fuel tank sealant. It as service temperature range from 65F (-54C) to 250F (121C), with intermittent excursions up to 275F (135C). This material is designed for fillet sealing of fuel tanks and other aircraft fuselage sealing applications. The cured sealant maintains excellent elastomeric properties after prolonged exposure to both jet fuel and aviation gas.

P/S 890 Class B is a two-part, manganese dioxide cured polysulfide compound. The uncured material is a low sag, thixotropic paste suitable for application by extrusion gun or spatula. It cures at room temperature to form a resilient sealant having excellent adhesion to common aircraft substrates.
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Old 01-27-2019, 06:00 PM
  #29  
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Originally Posted by Jonnyu View Post
Okay Lots of ideas. I’m thinking of using the split ring. Tank has rivnuts so I will have to remove the working ones to install the split ring. I found this company is down the street from me.
Stainless Steel Underring (for SSS & SSL sensors)

this will work. If I don’t remove the working rivnuts I’m going to seal the send with PRC 890. This is what we use to Seal tanks in aircraft. If anyone is looking for some you can pick up at aviall. Just remember to spray mold release if not you will have a hell of a time removing it. On aircraft we shoot a dab of sealant into the screw hole and thread screw in. If you buy some to repair your tank buy 890-B2 as it kicks in 2hrs. B1/2 only has working time of 30 min. I will update post once I’m done. I’m going to go ahead and replace the other sender on my other tank. This way I don’t have to deal with it again. (Hopefully)

Rivnuts??

Wait, is this a poly tank??? If so , I don't recall seeing you had mentioned that . I've never seen rivnuts in an alu tank.

...If.... that is the case, I've replaced rivenuts by removing the originals, running a long semi-stiff wire down through the fastener hole and back out the large sender hole and through the replacement and bend that end of the wire to retain the new rivnut . Heat the replacement sufficiently, and draw it through the sender hole and back up into the rivnut hole in the poly to melt in place. Once it is quickly cooled it is ready for the fastener.

Caution: DO NOT USE A TORCH ANYWHERE NEAR GAS FUMES!

In lieu of heating to melt temps , you might have luck installing replacement rivnuts bedded in PC-7 epoxy

But the split ring can work in poly tanks as long as you can get it to sit reasonably flush with the inside of the tank top and adhere OK.

Last edited by TTaxi; 01-27-2019 at 06:08 PM.
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Old 01-27-2019, 06:34 PM
  #30  
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If it's a poly tank that's a lot different. You're only options are the split ring or a new tank. And to those saying permatex 1 or 2 I'm glad you only work on your own boats.
It might be ok on a gasket but not sealing a leak in a tank.
Those telling you to use 5200 on a fuel tank, let's hope they take their boats to a marina for service.
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Old 01-27-2019, 06:39 PM
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Tank is aluminum. This is what is installed
https://en.m.wikipedia.org/wiki/Rivet_nut
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Old 01-27-2019, 06:53 PM
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Originally Posted by Jonnyu View Post
Tank is aluminum. This is what is installed
https://en.m.wikipedia.org/wiki/Rivet_nut
Did those rivet nuts come out, and that's why the holes are so big?
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Old 01-27-2019, 08:39 PM
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Originally Posted by sjef View Post
Did those rivet nuts come out, and that's why the holes are so big?
exactly...
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