Removing 4 Repair NL2 Aux Tank

[PbFut]

I am not having any success with breaking free the rods that mount my aux tank. Does anyone have a photo of the hardware? Or a source? I am unsure where the frozen threads are located. I am thinking it best to grind the mounting hardware heads for the tank in the bed of the truck retaining as much of the original hardware as possible. Then replace or repair the head portion of the hardware for remounting after I clean and restore the tank and free up the hardware. My guess is that the frozen threads are in the passthrough tube in the tank. This is not a high quality restore, I just prefer to retain as much of the hardware/original look as possible. Running some althread would be fast and easy but not the look I want. The odd retainers on the bottom of the tank being the items I would prefer to save.

[BASE]

Is this the same tanks being talked about here: https://67-72chevytrucks.com/vboard/...33#post9082833

I’m not familiar with the NL2 terminology. If it is, I had one that the nut part fit pretty tight inside the tank/tube. I had to use penetrating oil, heat, a big hammer and a lot of cuss words to get that one out. I think making a spanner to fit those drain holes would help but I haven’t gotten around to that yet.

[PbFut]

Yes. Thank you. My search did not return that post. Just what I needed.

[Gyrine]

I started the post. My truck has a travel tank band axillary tank. The retaining nuts in the pictures are from my tank. I drove a chisel in mine to get them out as the 3/8 square head rounded off. I had soaked the retaining nuts and bolts from the top of the tank for weeks. Fortunately, the bolts look fine.

[PbFut]

I am in the soke process now with some 25 yr old Break Away. Way different properties than the current formula likely due to EPA rules of today. One moved slightly but I am not holding out that they are going to give up. This is a Factory Option tank but the nuts in your thread look very similar to mine. There was a lot of dirt in the holes. I am thinking if I can't get the nuts free, I'll grind the carriage bolt head in the bed off. Then hopefully be able to separate once out of the tube running through the tank. Seems it will be easier to replace the long bolt than it will be to locate those nuts. If my procedure appears flawed please comment.

[BASE]

That is what I ended up doing with one of them. The nut seemed to fit tight enough into the hole that it was pretty well welded to the tube. Even after I got the tank out it did not want to budge. Took many hits with a sledge to get it out, and it came out looking like some of the metal had been torn off the OD of it. I was really surprised I didn't damage the tank.

I'm definitely going to have to make sure those drain holes stay open once I get it back into service. Probably something to add to the annual maintenance list. I'm thinking I might mill some slots on the outside of the nut just to make sure water can drain around it. It was obvious it wasn't draining well on that one. The end of the threaded carriage bolt was mostly rotted off and the inside of the nut was bad too.

[knuckle-nurse]

I ground the heads off the carriage bolts and removed the tank. The tank, bolts and special nuts were a solid rusted mess. Its amazing the tank didn't fall out. I'm having the tank replicated by a local fabricator. The member that supplied the special bottom nuts (He had one good example and had a machine shop in his area replicate them) has not responded to my pms.....I'll keep trying. I could not find a supplier of the 7/16-14x 12" carriage bolts so I ordered 3 correct size 12" stainless threaded rod from McMaster Carr. Will get some stainless rounded nuts machined for the top and should be good to go.

[BASE]

I’ve been laid up in the hospital for the last 5 days (just got home last night) so I haven’t made any progress with my plans to try making some. If I can scrounge up the right stock I’m going to make a point to get to it this weekend. Seems like a fairly straight forward project but I have a real talent for messing up stuff when I get ahold of machine tools and welders.

[PbFut]

Get yourself better. Please share your results when you can. I have to head up to Wyoming next week for a memorial. An old neighbor and fellow hot rodder recently passed.
I'll have to let things sit till I return. At this point it's not looking good for these nuts. There is zero movement. The post a few months back by the fella with the rusted carburetor studs is inspiration. We shall see.

[kwmech]

When going back together grease the snot out of the threads with the water proof wheel bearing grease for boats. The new anti-seize that is in the auto parts stores now-a-days is junk and dries out.

[BASE]

I haven't forgot about you guys, I've just been moving pretty slowly lately. I did get some of the barrel parts turned today. The pile of discs I ordered haven't shown up yet. I'm really hoping they at least get here before the weekend.

[best view]

Glad your better

[BASE]

Been a rough week but I'm still trying to get something done with these. I got the 2" discs in today and tried out my homemade press die...not a stunning success, but not a complete failure either I guess. I was really hoping the thing would mash down the rim of the washer like the originals. I don't think my 12 ton press has enough oomph to get it done. I may just turn a bit of a flat on top so it's not sharp where it sits against the tank, and call it good.

[Gyrine]

Base,
Hope you are feeling better. I like what you are doing in respect to the retainers.

How are you going to make the square slot in the center?

I ask because I think that is the week point of the original design. My retainers started rounding off with very little pressure from my 3/8 socket. Therefore, it might be more functionally sound to make the disc a little thicker than the originals. Just my opinion.

Thanks for your efforts on this.

Rob

[BASE]

I don't have any good ideas there other than to drill a 0.375 or so hole and go to town with a square file until it fits a 3/8" ratchet. The material I'm using is a bit thicker than the original. 0.125" vs 0.100".

The hole on the original is not really square, and not really 3/8" either. The one I have that's in the best shape measures ~0.400 but it's kind of a star shape and not a perfect square.

[BASE]

More on the square hole thing:

I've attached a pic of the best 2 out of 4 nuts I have. I'm not sure if that pattern was caused by a previous owner or not. Seems unlikely they would make them that way. Probably just deformed by prior installation or removal. It does appear that they were made with a square that's bigger than what would be a tight fit on a 3/8" drive though, if you look at the corners you can see the ID of the nut part.

I almost stopped during the removal of my PS tank and tried to fab up a wrench that would engage the 2 round drain holes. I think that might provide some better leverage, but I was in a hurry and just destroyed them with my 3/8 drive breaker. I may see if I can make something out of some decent metal to engage those drain holes. Probably need to be 4140PH and not the junk I have laying around. There really isn't room to make those holes bigger than 3/16".

Things like this always seem so simple until I actually get around to "doing".

If anyone has any ideas here I'd love to hear them.

[PbFut]

My retainers do not have the round holes. Just the square center with smooth sides. I believe them to be factory original 1972. Seems to me a spanner wrench would work on the holes on your retainer. Should provide way better leverage.

[BASE]

Okay that is interesting. I'm assuming mine were added after production, they have a "Travel Tanks Travel Accessories Inc, Orland Calif" sticker inside the fuel doors, and nothing on the SPID that would indicate it came with them.

I'm wondering if the holes were added later due to corrosion issues. The two I had that were really rotten appeared to completely plugged with crud.

[Gyrine]

My truck has a "travel tank" tank. The retainers have the two holes like yours. I also trying to remove with the two small holes before destroying the square holes.

I totally agree with you in resect to the square hole size. It is a shade bigger than 3/8.

Do you all think there might have been a special tool back in the day that either fit snug in the square hole or worked with the small holes?

[BASE]

I modified the disc smasher to make it easier to drill holes, and facilitate turning the edge off once it’s mashed. Now I just need to get my TIG put back together so I can finish a few of these things up.

[PbFut]

Base, Nice progress on the tooling.
Base made me feel guilty not getting to the removal job so I got on it yesterday. Here are a few lessons learned.
Easter Eggs are likely in the work area.
Going very slow it was a 2-3 hour, rather dirty job.
Do not attempt to remove the retainers from the bottom. The chance you will destroy the square 3/8” hole is nearly 100%. Even after weeks of soaking the retainer with penetrating Break Away oil, they were still frozen by corrosion. I wish I would have simply ground off the heads of the carriage bolts in the bed saving the retains condition.
Carefully grind the 3 carriage bolt heads in the bed holding the tank. They are soft and grind easily. Place a jack under tank but leave a small space so the weight of tank pulls the last bit of bolt head and breaks it free. If you are careful, you won’t damage the original oval washers in the bed.
I found a cool easter egg behind the filler cover. An old Hide a Key box with what appears to be a original GM key. An odd place for one but certainly a secure location.
Once the tank is dropped, you can work getting the retainers off the carriage bolt. You will have much better angle to get the Break Away oil on the threads and more leverage.
A correction on a previous post in this thread I made concerning the small holes in the retainer. The retainers on my 72 GMC C2500 DO have rather small drain holes. Much smaller than the photo Base posted above.
They are not large enough for a spanner tool and likely would not work to break free the corrosion even if you make them bigger to fit a tool.
Sorry I don't have a good photo host so no pics.

[BASE]

Originally Posted by PbFut

Base, Nice progress on the tooling.
Base made me feel guilty not getting to the removal job so I got on it yesterday. Here are a few lessons learned.
Easter Eggs are likely in the work area.
Going very slow it was a 2-3 hour, rather dirty job.
Do not attempt to remove the retainers from the bottom. The chance you will destroy the square 3/8” hole is nearly 100%. Even after weeks of soaking the retainer with penetrating Break Away oil, they were still frozen by corrosion. I wish I would have simply ground off the heads of the carriage bolts in the bed saving the retains condition.
Carefully grind the 3 carriage bolt heads in the bed holding the tank. They are soft and grind easily. Place a jack under tank but leave a small space so the weight of tank pulls the last bit of bolt head and breaks it free. If you are careful, you won’t damage the original oval washers in the bed.
I found a cool easter egg behind the filler cover. An old Hide a Key box with what appears to be a original GM key. An odd place for one but certainly a secure location.
Once the tank is dropped, you can work getting the retainers off the carriage bolt. You will have much better angle to get the Break Away oil on the threads and more leverage.
A correction on a previous post in this thread I made concerning the small holes in the retainer. The retainers on my 72 GMC C2500 DO have rather small drain holes. Much smaller than the photo Base posted above.
They are not large enough for a spanner tool and likely would not work to break free the corrosion even if you make them bigger to fit a tool.
Sorry I don't have a good photo host so no pics.

That's interesting. I'd kinda like to see what your retainer nuts look like. I'm also curious about the tank itself. Mine only had 2 bolts per, so I'm wondering if they are a completely different animal than what I'm dealing with. I know I remember seeing some smaller tanks posted on here in the past. I believe mine are 20 gal tanks (one on each side). Seems like most just have one though.

I think you can upload to the site without a host if you click on "go advanced" and then "manage uploads". I always email the pics to myself on my phone to get them shrunk down to a more reasonable size. Iphone asks you if you want to shrink when you send the email. Probably more elegant ways out there but that works okay for me.

Funny I just remembered that I found a hidden box and key when I took mine out as well. I remember thinking that putting the spare key behind the fuel door (which requires a key) is something I would probably do

[PbFut]

Here are 3 pics. I tend not to photograph as I go. I'll get some better ones late today
Thanks for tip on attachments.

[BASE]

Thanks for posting that. They look similar, but are definitely a slightly different animal than what I have.

I've been having it rough go at it with my project. I manage to break my lathe drill chuck, launching pieces of it all over the shop which I still haven't been able to recover. Last night I broke a drill bit off in my makeshift drill guide, then like an idiot ran the only other 3/16 bit I had into the remnants of the broken one. The upside is that I'm an even worse welder than machinist so I've got that to look forward to.

[Beach-Burban]

Originally Posted by pbfut

here are 3 pics. I tend not to photograph as i go. I'll get some better ones late today
thanks for tip on attachments.

This will probably not add anything to your discussion as my dealer installed 45 gallon "Travel Tank Inc" tank was made for a Suburban...but it has four of the long carriage bolts with the special retainers that get destroyed during removal. I was lucky as three of mine came out in reuseable shape, but one did not. The problem I had was the retainer was locked solid to the carriage bolt (wish I has ground the head off before mangling the retainer) and the bolt was fused by corrosion inside the tube. After grinding the carriage head off, the tank dropped down and out but it took severe pounding (and a lot of penetrating oil) to break it free. We needed to inspect the tank inside and out then check for leaks...and luckily again, all was good. I used all-thead and nyloc nuts in place of the damaged one...but I still look for an original type replacement when at the swap meets. Base...your remedy looks fantastic!

Woody