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914World.com _ 914World Garage _ Did I just trash the fuel tank ?
Posted by: Literati914 Aug 24 2023, 06:46 PM
Has anyone successfully recovered from stripping the threads from one of the fuel line connections on the bottom of the fuel tank?
The 22mm aluminum nut that’s closest to the tanks perimeter seam was very snug but still moving while I was removing it. Once off I could see that both the male steel threads and the aluminum nut were stripped (basically at the top of the steel male section - so the nut won’t start). I have an extra aluminum nut but it wasn’t making much headway towards recutting those top threads.
Perhaps a die would recut them .. but then it is pretty close to that seam. Has anyone had to do this? Did a die work? What dimensions and pitch ?
Thanks.
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Posted by: jhynesrockmtn Aug 24 2023, 06:51 PM
Has anyone successfully recovered from stripping the threads from one of the fuel line connections on the bottom of the fuel tank?
The 22mm aluminum nut that’s closest to the tanks perimeter seam was very snug but still moving while I was removing it. Once off I could see that both the male steel threads and the aluminum nut were stripped (basically at the top of the steel male section - so the nut won’t start). I have an extra aluminum nut but it wasn’t making much headway towards recutting those top threads.
Perhaps a die would recut them .. but then it is pretty close to that seam. Has anyone had to do this? Did a die work? What dimensions and pitch ?
Thanks.
.
I have a trashed tank. If you need those pieces cut off so you can weld good ones on, I can cut them and send them to you. I would only bother if the tank is otherwise in great shape. New ones are under $300.
Posted by: Literati914 Aug 24 2023, 07:04 PM
Has anyone successfully recovered from stripping the threads from one of the fuel line connections on the bottom of the fuel tank?
The 22mm aluminum nut that’s closest to the tanks perimeter seam was very snug but still moving while I was removing it. Once off I could see that both the male steel threads and the aluminum nut were stripped (basically at the top of the steel male section - so the nut won’t start). I have an extra aluminum nut but it wasn’t making much headway towards recutting those top threads.
Perhaps a die would recut them .. but then it is pretty close to that seam. Has anyone had to do this? Did a die work? What dimensions and pitch ?
Thanks.
.
I have a trashed tank. If you need those pieces cut off so you can weld good ones on, I can cut them and send them to you. I would only bother if the tank is otherwise in great shape. New ones are under $300.
Yeah the tank is in good shape otherwise.. thanks for the offer (I’ll keep that as an option) however, I’d rather not have to weld on it as I would need to pick up a whole welding tank for just this job (plus I’m spooked about welding old fuel tanks, tho I’ve done it before).
A narrow die might work, if there’s such a thing.
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Posted by: Superhawk996 Aug 24 2023, 07:14 PM
Try a thread file
Posted by: Literati914 Aug 24 2023, 09:02 PM
If knew the thread pitch and size, I might could make a die… by purchasing a steel nut and cutting it in half, clamp it low on the threaded section w/ vice grips and work it back and forth. Ghetto 
I know! A steel nut is no die but may be a cheap thing to try IF an actual die is not available 
Anyone know the specs?
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Posted by: Literati914 Aug 25 2023, 09:23 AM
Just to update the thread - I’ve found that the thread dimensions or nut/die needed is M18x1.0 .
Apparently ‘95 Nissan trucks used this size for spindle nuts, and someone here in the distant past has successfully used it as a chase after cutting a V-notch inside the thread area, with a triangular file. A die was tried but was too wide to fit the area. So I’m gonna source an M18x1.0 nut and try the same, with liberal amounts of cutting oil.
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Posted by: r_towle Aug 25 2023, 11:29 AM
I would be very grateful if you could post pictures of how you modify a nut to do this rescue. I can’t figure out what you are going to use/do to create a cutting edge.
Posted by: worn Aug 25 2023, 11:35 AM
You might get closer in by flipping the die around so that the starter threads face out. That way you will get cutting pretty much from the start.
Posted by: cholland_ Aug 25 2023, 11:37 AM
I tried a both a thread file and a die, but didn't have any success (not enough space between the two connections).
I ended up getting a NPT tap (I believe 1/4", but don't quote me on this), and using an AN adapter to a 90 degree barb. Works perfectly, no leaks.
Posted by: Literati914 Aug 25 2023, 01:40 PM
I would be very grateful if you could post pictures of how you modify a nut to do this rescue. I can’t figure out what you are going to use/do to create a cutting edge.
back in 2014 a member named @http://www.914world.com/bbs2/index.php?showuser=1608 had this issue and used a steel M18x1.0 jam nut and cut a groove in it with a file so that it could be walked back and forth in increments and trap cuttings, clean and repeat 'til all threads are uniform.
Here's a picture with the inscription:
"Cut a groove with a triangle file. Worked like charm."
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Posted by: Literati914 Aug 25 2023, 01:48 PM
BTW, I was able to clean up the steel threads with a very sharp pick .. yes there was some aluminum embedded in the steel of the male side, that I couldn't distinguish at first. Some of the steel threading was also damaged tho. After cleaning the threads with the sharp pick, I was able to use a good aluminum nut (because I have extra and no steel one yet), and recut the steel threads enough to get the nut to thread on. This is probably good enough but I don't really like the feel of the threading action, so I'll still be doing some thread chasing with the modified steel nut when it comes in. But, the good news is that, no I did not trash my tank ! 
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Posted by: worn Aug 26 2023, 09:44 AM
BTW, I was able to clean up the steel threads with a very sharp pick .. yes there was some aluminum embedded in the steel of the male side, that I couldn't distinguish at first. Some of the steel threading was also damaged tho. After cleaning the threads with the sharp pick, I was able to use a good aluminum nut (because I have extra and no steel one yet), and recut the steel threads enough to get the nut to thread on. This is probably good enough but I don't really like the feel of the threading action, so I'll still be doing some thread chasing with the modified steel nut when it comes in. But, the good news is that, no I did not trash my tank !
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Nothing like the love between aluminum and steel.
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