Looking for a little help

Actually I really want to have the rusting fuel tank of my '83 RX-7 properly replaced with a new or better "reclaimed" one but they are no longer made
and most of the auto relaimation centers (junkyards to you and I) cite the near impossibilities of shipping a used tank these days. The nearest one in "really good shape for its age" (and he won't send digital pix of it either) is nearly 1000 miles round trip. Yes I am on vacation this week but I want to be driving the RX not fetching parts all across the US.
Correctly done the rusted through spot should be cut out and a new piece of 18-20 ga steel welded or brazed in place. I am a simple stick welder and this is way beyond my current abilities. I have not searched out a local master fabricator as yet but I can if need be. Truly there is a "L" shaped section about 6" by 12" that is fairly rusty on the outer surface but the inside coating seems to be fine. That is except for the 4 quarter sized spots that have actually rotted through. This section is where the frame rail comes in contact with the tank. I even found a mouse nest in the frame rail so I am sure that the little bit of salt the car has seen was also augmented by rodent piss. Yes, I did evict them for now but expect them back next winter when I store the car.
My mechanic has suggested a product called POR15. He claims you clean the area grom grease and grime and any loose rusted metal and simply paint it on. It is thick enough so that he would add some fine fiberglass cloth to fill the holes and apply another coat right over it. After it is all cured I could then go ahead with the recoating of the inside of the tank although now that it is off and I have peered in through the openings it really looks fine. The main reason for the recoating though is that the rust issue is near the openings I am looking into the tank through and can not really assess how bad that side of the tank is internally.
After the holes are repaired I plan on a good all over cleaning and priming with Rustoleum Rust Reformer before spraying a body undercoating over the whole of it. I have followed many threads here and respect the knowledge behind this forum. That is why I ask you, The Experts", will this work and allow me to drive my sports car another 5 years or so? By then I hope to retire and can learn a lot more about brazing or wire welding.
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I have some ideas, 1, your mechanic may just know what he is talking about. I have heard from restorers of old cars abouit some compound that you pour innto the tank, slosh it around untill all of the interior is coated, allow it to dry and your tank becomes linned internnally. 2, 31 years ago, I had a car with a tank that rusted through from the standing water in the bottom corner of the tank. I took it to a radiator shop and they soldered it up using an electric soldering iron (no flame) and 50/50 solder with acid flux. Sold that car 3 years later. 3. I suggest you consult with restorers of old cars, this is dertainly a common problem eor them.
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I have ordered the internal liner epoxy for when the mechanical outside repair is done. The issue I will have there though is the 3 non removable tubes that serve as out to fuel pump, return from fuel pump and the clean air box vent. there really is not a way to plug them on the inside of the tank because I can't reach them. They are steel tubes that are brazed where they pierce the skin of the tank. I am considering cutting them below where they have a 90 degree bend to be able to insert a wooden dowel or metal rod for the coating process and then using a right angle compression type fitting to get the 90 back on it so the "rubber" tubes will fit. Then again they do make 90 degree "plastic" fittings so I could go that route too. The quotes are because of the fact I realize a huge concern these days is the ethanol in the gas.
As to the solder, that was my first thought and I may flush the tank with water and give it a go with my solder gun. I would need to fashion metal plugs to cover the holes though as the holes are too large to bridge with solder alone. Certainly "doable" but since it is on the upper flat surface I was hoping to avoid doing it. If there were a bunch of pin holes you can bet I would sand the surface with my palm sander and simply skin coat the whole of it with lead.
From what I found on my research the restorers all swear by these new chemicals. A few naysayers but most of them have admitted to mis applying the products in some way. If you are going to use a "new" technology you really ought to follow the directions fully is my feeling.
Thanks again
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Krazy Old Man wrote in sci.engr.joining.welding on Mon, 18 Apr 2011 07:57:33 -0400:

I wouldn't recommend cutting off the steel lines. Could you blow through the tubes to clear the epoxy after coating, and prop up the tank so any excess won't settle in the pickup area. When you coat the tank you should pull the sending unit, and then you might get a better look at the inside.
--

Dan H.
northshore MA.
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I have the sending unit out and have been trying with various tools to reach in and put corks or caps on the tube ends. Does anyone make a 15" long set of needle nosed pliers? My fear is that this lined stuff will set up and blowing with a compressor either won't work or it will leave some debris to clog the lines afterwards. I DO agree with you that cutting the lines is not my first choice but it may be the best. I'm thinking of the compression fittings used in plumbing that have a right angle and a pipe thread on the other side of the 90. onto the pipe thread I would screw a fitting made for rubber hoses. You know the shape I am sure. What you but the hose on in science class for the bunsen burner. All of the threaded (possible leak locations) would be gooped with a fuel resistant gasket cement...or a dab of thie liner "paint".
Thanks again,
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Gasoline now contains ethanol. Tanks are no longer made of steel. Best choice would be to select a modern plastic tank and fit it into the space.
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[snip]

[snip]
Here's how NOT to do it:
http://www.dyna.co.za/cars/Car_-_Fuel_tank_welding.jpg
Bob
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== All google group posts are automatically deleted due to spam ==



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Thanks BobW for the tip. (I aint that dumb) Holy crap! If it is still mounted under the truck I bet he didn't flush it with water even. Did he make it into the Darwin awards as an honorable mention at least?
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Krazy Old Man wrote in sci.engr.joining.welding on Sat, 16 Apr 2011 08:04:27 -0400:

I have used POR-15(over rusty steel), and the fiberglass application you mention is on the can label. If you go this way, pour what you need into a septate container and brush from that. If you dip your brush into the can, what you don't use up will harden up.
I hope it works out for you, I loved both RX-7s that I had. Could have used a little more HP(mine had the smaller carbed engine), but I could out corner just about anything on four wheels.
--

Dan H.
northshore MA.
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Thanks Dan for confirming my mechanic's method. I have even found a piece of 20 ga steel that is surface rusted on both sides so I plan on cutting a few squares that are larger than the holes and painting them with the POR15 before placing over the holes. Then I will have some coated steel between the fuel and fiberglass.
My first was a 79 that I ran from Manchester NH to Pelham or Plaistow (I was working for RadioShack). Sold it to a guy who gave it to his daughter. She had never driven a stick and ruined the tranny within a week. (5th to reverse while on rte 213) and 3 months later I heard she wrecked it. Mine is the same 1.2L carbed 100HP.
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There's also a coating franchise outfit, http://www.gastankrenu.com /
I've used them a couple of times, for customers. Though I also know a decent radiator shop that does all manner of repairs on tanks (now).
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Thanks to all for the good ideas and the tips on how not to do it. I did find what should be a perfect replacement in Washington (state) and the "yard" there has a shipper that can get it to me for a reasonable rate. They also have a few of the interior trim pieces that I needed too so it was a better deal than I had hoped for.
So since I had a suitable replacement on the way I let an aquaintance of my son remove the rusted out section and braze a new piece in. Chris also filled the pin holes he found elsewhere on the tank. His final check missed one last hole that formed near his work. Likely that last tap with the hammer did it. I was able to clean it off and fill it with lead. Between the propane torch and solder gun I got a fair patch over the hole. I then degreased the tank, "Metal Readied" it and went about painting the POR15 on. I brush painted the whole tank first and then put a second application on in the more rusted areas.
As my mechanic had suggested, I then cut some fiberglass cloth into various sized strips and pressed them into the paint in the areas that were most affected by rust. The POR15 was then brushed on over the cloth to further seal the areas. I then hung it near the woodstove to cure over night. This morning I stuck some Ice and Water Shield to the surfaces that will be in contact with the frame of the car when remounted. For those not familiar with this stuff it is usually used in the construction industry. It is a rubberized self sealing membrane with a peel and stick backing. Once stuck it is a pain to get unstuck. Typically the last 4 ft of a roof or any roofing valleys have this directly on the plywood decking and the roofing is nailed over it. Lastly the bottom was resprayed with asphalt undercoating. The POR15 is plenty hard but it is not UV stable and being the underside I felt a bit of undercoating would keep the stones kicked up from the road from chipping it.
Now for the real reason of this particular post. I love this stuff! POR15 was brushed on but setup to a mirror self leveled finish. If it sticks to the metal as well as it is stuck to my hands it will never come off. I should have known when the solvent that they make for it says right on the label that it will not soften or disolve the POR15 once it had cured. That that was my second warning to wear gloves. OK...I am a Krazy Old Man that figured I would have a few minutes at least to get it off my hands. I have tried brush cleaner, the POR15 solvent, kerosene, gasoline, Cascade (magic stuff for cleaning frying pans and the like) Comet cleanser, adhesive remover and a few others that escape me right now. Currently (24 hours later) I am able to peel strips off my hands but it is going very slowly. As the skin refills with moisture/oils the paint loosens up and can be peeled much the same as with urethane glues or super glue.
So the lesson is WEAR Gloves if you use this stuff.

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Krazy Old Man wrote in sci.engr.joining.welding on Sun, 24 Apr 2011 10:59:13 -0400:

Not needed, as it is very tough as well as hard. But it should be topcoated just for the UV protection.

Shoot, I knew there was something else I should have told you about POR15. Well, it will come off, as your skin wears off. Should take about 3-7 days depending on how porous your skin is.
--

Dan H.
northshore MA.
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