Rust in the gas tank

[Brian_Heil]

Have had several cars tanks sealed by Gas Tank Renu, all over 20 years ago.  Still perfect.  Lifetime guarantee in the file.   Very happy with the performance. 

Looking at their website I see the original store is in Swartz Creek, MI about 10 miles from my home.  This is now a big franchise. 
 

https://www.gastankrenu.net/about

Edited November 9, 2022 by Brian_Heil (see edit history)

[Morgan Wright]

I think Renu is for leaky rusted out gas tanks. Mine just had a ton of rust IN IT could have been from elsewhere, such as a rusty storage tank or something. This tank itself is solid as a rock.

[EmTee]

Does the tank have a drain plug? If not, it might be a good idea to add one.  That would allow you to occasionally drain-off any accumulated water and solids.

[Bloo]

I think I'd be tempted to treat it with phosphoric acid. I can't remember ever doing that, so maybe there's some gotcha but I doubt it. The derusted tank has a massive surface area due to the pitting, and will try to flash rust almost immediately. Anything to slow it down a little would probably be a good idea.

 

Gas tank sealers have their proponents, but I don't believe in them. They are going to fall off eventually and cause a big problem. Think about how hard it is to "seal in" the last traces of rust on the outside of a car, even when you can see. Why on earth would it be any better when you can't see?

 

For what it's worth, gas tanks can be really bad and not cause much trouble, particularly if you have a sock filter. On any car that does not have one (except gravity feed), I add one as long as I can do it without hacking things up. Iron and other heavy stuff falls off the sock to the bottom of the tank, and might or might not ever make it back up. The tank becomes a giant sediment bowl. Of course a little will get stuck in the sock, and maybe if there is enough it will plug it. If that happens it's time for a new tank or a fairly invasive repair of the old one. Socks hold back water too, although that may matter less with all the alcohol that is mixed in gas these days.

 

[Morgan Wright]

8 hours ago, EmTee said:

Does the tank have a drain plug? If not, it might be a good idea to add one.  That would allow you to occasionally drain-off any accumulated water and solids.

 

That would work if my tank was shaped like this:

 

[neil morse]

1 hour ago, Bloo said:

Gas tank sealers have their proponents, but I don't believe in them. They are going to fall off eventually and cause a big problem. Think about how hard it is to "seal in" the last traces of rust on the outside of a car, even when you can see. Why on earth would it be any better when you can't see?

I'm curious about what you say here.  When I found the inside of my gas tank was rusty, I asked around (and on this forum) about advice on what to do.  Some recommended that I use a sealer that I could buy in a can, and just slosh it around in the tank.  I was concerned that this was not going to work, for exactly the reasons you mention.  It was bound to come off and cause problems.  However, the procedure of sand blasting all the rust off the inside of the tank first, and then having a professional use a plastic sealer, seemed like a good way to go.  I believe this is essentially what the "Gas Tank Renu" process is.  I took the tank to a local radiator shop, where the guy cut a few holes in the tank and then thoroughly sandblasted the interior before welding it back together.  He told me that "nothing will stick to rust," but that the sealer he used would stick to the bare metal and would not come off.  He then applied two layer of a white, milky-looking plastic sealer.  Do you think that even this will "eventually" come off?

[Bloo]

Well, some people here have had very good results with sealers. I'm not saying they are wrong. Depriving the rust of a ready supply of oxygen certainly slows it way down. In my experience though, anywhere there is even the tiniest bit of rust in steel, it will eventually expand and push loose whatever is painted or glued over top. The whole idea of that bugs me. Your mileage may vary.

 

 

[Morgan Wright]

Now that the tank is rust free and installed, and filled to the rim with 14 gallons of ETOH-free gasoline, to keep the moisture out, I have to fix the gas gauge. Here is what I have. The gears are aluminum or pot metal (no attraction to magnet) and the float rod is iron (magnetic). The solder is broken. Anybody expert on soldering iron to whatever random metal the bevel gear is made of? Should I just heat the old solder and let it knit, or maybe add some new solder to the mix? 60/40 with core flux? What are the risks of destroying the aluminum if I use a torch? I sure would like to get this fuel gauge working right.

[Rock10]

how about epoxy?

[Daves1940Buick56S]

JB Weld?

[Bloo]

Gas will eat most epoxies over time. I have tested JB weld in gas. It gets soft. Probably a special purpose epoxy for that exists, but I have not used one.

 

Morgan: Tread slowly and carefully. You need to figure out exactly what that metal is before proceeding. If it is aluminum or zinc, just heating it ain't gonna work. You need to have a plan. Soldering to aluminum is almost impossible, and when done usually involves scraping around in the solder pool to release the oxidation layer, something you wouldn't be able to do where parts mechanically fit together like that. I don't recall what flux is used for aluminum, but Harris probably has something. Zinc can be soldered. I have done it with water-based zinc chloride flux, the late great "Sterling" plumber's flux. Killed acid would probably work. The problem is the melting point of the zinc is just barely above the melting point of the solder. It might all collapse. When I did it successfully it was steel mounting studs, about #6 or so, also riveted but the rivets were loose, on sheet zinc. I used a 500W American Beauty iron. The base metal was melting a little when the solder finally flowed, and it is a miracle it didn't all collapse. I don't think you could control the heat well enough with a flame, but I didn't try it. Keep us posted.

 

Edited November 12, 2022 by Bloo (see edit history)

[Morgan Wright]

1 hour ago, Bloo said:

Gas will eat most epoxies over time. I have tested JB weld in gas. It gets soft. Probably a special purpose epoxy for that exists, but I have not used one.

 

Morgan: Tread slowly and carefully. You need to figure out exactly what that metal is before proceeding. If it is aluminum or zinc, just heating it ain't gonna work. You need to have a plan. Soldering to aluminum is almost impossible, and when done usually involves scraping around in the solder pool to release the oxidation layer, something you wouldn't be able to do where parts mechanically fit together like that. I don't recall what flux is used for aluminum, but Harris probably has something. Zinc can be soldered. I have done it with water-based zinc chloride flux, the late great "Sterling" plumber's flux. Killed acid would probably work. The problem is the melting point of the zinc is just barely above the melting point of the solder. It might all collapse. When I did it successfully it was steel mounting studs, about #6 or so, also riveted but the rivets were loose, on sheet zinc. I used a 500W American Beauty iron. The base metal was melting a little when the solder finally flowed, and it is a miracle it didn't all collapse. I don't think you could control the heat well enough with a flame, but I didn't try it. Keep us posted.

 

 

Now I'm more scared than before. I think I'll abandon the idea of soldering it. It probably will destroy everything; those pot metal gears look super fragile. It fits really well when I squeeze it in, maybe I'll just snap it in and wrap fine steel wire around and around. No, steel rusts. Maybe thin copper wire.

[Bloo]

That just might work.....

 

[Morgan Wright]

And a new cork from a new wine bottle. Gotta stop drinking these cheap box wines, I need a cork.

 

That cork looks good for 105 years, huh?

[Bloo]

LOL yes, but seal the new cork up with something. I tried to re-use my old ones. I sunk them in ethanol laced gas for a week and they didn't get heavier so I used them. A few months later they sunk. The oft-repeated tale in forums that cork doesn't need sealing because it is a closed cell structure is bunk. Apparently it isn't quite that simple. There has to be more to the story. The automakers used shellac, but that's no good in alcohol. Things I have heard of being used are super glue, model airplane dope, por-15, and gas tank sealer. I used pre-sealed corks from Bobs and they seem to be holding up, so I don't know what sealer is best.

 

Edited November 12, 2022 by Bloo (see edit history)

[Morgan Wright]

This says it all

 

.

[MCHinson]

A better long term solution for the float would be this: https://www.brattons.com/GAS-GAUGE-FLOAT/productinfo/13550/ 

 

Cork will eventually fail no matter how well you seal it. 

[AzBob]

X2 on what Matt posted only I ordered mine from Restoration supply. The material is called Nitrophyl. "Used to replace old cork floats. Machinable and impervious to gasoline."

 

[Morgan Wright]

Thanks

[Bloo]

You could probably make a case that stuff is better than cork.... I guess. I question how much better. It has the same issues as cork. It is a "closed cell material" that "cant absorb fuel" and "cant sink", except that it does sink. Sound familiar? GM and many others used that for carburetor floats in the 70s and 80s. They worked for a while and then sunk. It was clearly inferior to the brass they had been using for carburetor floats before, which usually outlasted the car.

[Daves1940Buick56S]

Also nitrophyl supposedly has slightly different buoyancy than cork so you may have to adjust the arm. At least that is what they said when I replaced the floats on the carbs on my TR-3.

 

Cheers, Dave

[DonMicheletti]

While having a working gas gage is nice, since the fill hole on my '18 Buick is so big, when gas gets kind of low, I just open the fill port and have a look. Dead accurate.

I'm lucky, the original cork float on mine is still fine.

[1937McBuick]

I realize this thread got a little off topic but I would like to comment on the sending unit.

I bought a new one that fits the bolt hole pattern in my 37 McBuick.   But the orientation of the pick up tube and float is 90 degrees off the original unit's orientation.   I suppose I could re-drill the holes on the sending unit to match the tank,  then it would be facing the right direction.    Someone suggested just getting a new style where the float simply rides straight up and down.  Can't say I'd know if the mounting holes in the tank and sender would be remotely close or of the ohms range is suitable for the gauge(I guess I'd have to make sure of that).

 

I contacted SAR&R,  they supposedly quit rebuilding the old sending units but the Tech who did it is supposedly doing it on his own.  I've tried a couple of times to reach him but failed,  I even left a message one of those times.   I think Bob's Speedometer may also repair them, although I haven't tried reaching out to them yet.   I suspect there's afew places to have these repaired across the Country.

 

Mine was seized,  with a tiny bit of heat from a small propane torch where it was seized I was able to loosen it a bit.  A little WD-40 on the area and slowly and gently moving it back and forth I was able to get the float arm to travel its full range.   But the true test was yet to be done....hooked the multimeter up to the unit,  moved the arm through its range of motion.....and nothing.   The resistor and contacts are probably ruined or at the very least insanely dirty.   Which means the hollow rivets would need to be drilled and the top cap removed from the body.  I'm thinking that portion needs more than a "good cleaning".

 

Any thoughts or suggestions?

 

Re:  the rust in the tank.   I got an original tank from someone who is resto-moding their car.   I recieved it with the inside already coated with POR15.  When we cleaned up the exterior to put a coat of paint on we never noticed any spots where the coating bled through....so here's to hoping everything is ok, or it never comes off causing plugging problems.  Time will tell.

 

 

Edited November 13, 2022 by 1937McBuick (see edit history)

[Bloo]

1 hour ago, 1937McBuick said:

Any thoughts or suggestions?

If this is the typical 37 unit with gears about like Morgan's, but made of steel, there are 3 rivets on top you have to drill out. I rebuilt a couple of them. There is a wiper attached to the center shaft, and the electrical connection (a ground) is made to the contact via a spring riveted to the sender frame. Not really trusting the rivet, I soldered that. The resistor is nichrome wire wound around a piece of phenolic (or similar material). It has a curve that follows the cap. It is riveted down at one end, grounded as I recall but it doesn't need to be. The other end is connected to the binding post for the sender wire. It is just riveted over. It holds a plate underneath that shorts out a few turns so the wiper will be at 0 ohms at that end of travel. I fully expected the nichrome to be worn through and have to "rewind" them, but no they were fine. One was dirty, the other had become detached from the binding post. It was kind of a pain to fix that, but I did it by drilling clear through the center of the binding post on a lathe, and making a sort of rivet to go up the hole I made, then flowed solder through the whole mess. If you decide to do it make a thread. I might have more hints and maybe even some pictures if they are still online somewhere.

 

[1937McBuick]

Those pictures would be nice to see.   You know the saying....a picture is worth 1000 words.

 

Is there any seal where the shaft with the wiper passes through the sender frame?

 

Also,  my linkage seems a bit sloppy.   I didn't sand blast it,  "yet".   Maybe i should use something less abrasive,  like soda and just work at it longer and gentler.  A light blasting would clean it up nicely but what could I do to protect it from corrosion or building up with crud again.

Edited November 13, 2022 by 1937McBuick (see edit history)

[1937McBuick]

I don't think I've ever seen an NOS sending unit listed anywhere.  I would think there has to be some hidden out there somewhere or sitting on a shelf forgotten about or the owner unaware of what it fits.

 

That goes for gas tanks too.    The Old Buick Dawg, Dave Tacheny,  said a guy on the east coast supposedly has a couple(some?)  NOS tanks to fit my car(along with a pile of other various parts).    I need to watch how I say this, but hoarding parts that the owner will never use or doesn't even own the car for doesn't do anyone any good.    With the potential for fewer guys looking for those parts because of lack of interest or no one wanting the cars the parts fit...  what good does having the parts nobody wants do?   To a degree,  it might be harder to find a buyer the longer you keep them "not for sale".   But this could be a whole new discussion on its own....

[Bloo]

1 hour ago, 1937McBuick said:

Is there any seal where the shaft with the wiper passes through the sender frame?

No. There are 2 gaskets inbetween the riveted stuff up top. Easy enough to cut out. The 5/16" copper pickup tube is probably cracked. You'll probably need to sand-bend to get the tight radius, then cut your piece out. The old fitting easily sweat solders on, just like plumbing.

1 hour ago, 1937McBuick said:

Also,  my linkage seems a bit sloppy.   I didn't sand blast it,  "yet". 

I electrolytic derusted mine, and then zinc plated it to slow down the rust. Probably better than sand. Evaporust would clean it, but the electrolytic process is cheaper by far. They are sloppy. I think its normal. There is a brake down at the bottom with a keyed brass washer and a cork washer. If you rebuild this you have to unsolder the shaft from the bottom gear, Its like herding cats to solder it back together, because the clocking of the center shaft is also the calibration, and is critical. There is a spring trying to push it apart. Annoying, but very doable. Should have solid cork for the washer, not powdered cork/rubber gasket sheet. Cheap saxophone cork from China works well to make the washer (it's on ebay).

 

 

Edited November 13, 2022 by Bloo (see edit history)

[MCHinson]

1 hour ago, 1937McBuick said:

Those pictures would be nice to see.   You know the saying....a picture is worth 1000 words.

 

Is there any seal where the shaft with the wiper passes through the sender frame?

 

Also,  my linkage seems a bit sloppy.   I didn't sand blast it,  "yet".   Maybe i should use something less abrasive,  like soda and just work at it longer and gentler.  A light blasting would clean it up nicely but what could I do to protect it from corrosion or building up with crud again.

Sorry but since this thread has already been sort of hijacked, I will continue the current 1937 sending unit discussion since I can help with that...

Click on the arrow at the right top corner of the following link and it will take you to photos and a bit of discussion of my repair of a 1938 fuel sending unit. 

 

 

[1937McBuick]

16 minutes ago, Bloo said:

 If you rebuild this you have to unsolder the shaft from the bottom gear, Its like herding cats to solder it back together, because the clocking of the center shaft is also the calibration, and is critical. 

I realize the shaft that the gear is soldered to is very small in diameter but couldn't a fine line be etched into it and the gear where they're supposed to line up(done before un-soldering the two)?   Also,  etch one tooth on one gear and two on the other,  placing the single marked cog of one gear between the two marked cogs of the other gear.   There must have been something to guide the assemblers when they were made other than winging it by trial and error.

Edited November 13, 2022 by 1937McBuick (see edit history)

[1937McBuick]

Matt...

 

I apologize for my part in de-railing the tread,   I threw in the odd comment about the gas tanks trying to keep at least one set of wheels on the rails... lol!   Sorry

[MCHinson]

7 minutes ago, 1937McBuick said:

I realize the shaft that the gear is soldered to is very small in diameter but couldn't a fine line be etched into it and the gear where they're supposed to line up(done before un-soldering the two)?   Also,  etch one tooth on one gear and two on the other,  placing the single marked cog of one gear between the two marked cogs of the other gear.   There must have been something to guide the assemblers when they were made other than winging it by trial and error.

If it is in similar condition to the 1938 sending unit that I worked on, you won't need to unsolder anything. I just needed to remove the rivets at the top, separate the two halves of the unit, clean up the windings and slightly rebend the "wiper" to give it a little bit more pressure against the windings and it worked properly.  

[1937McBuick]

Bloo,  I edited my comment about sand blasting to pointing out soda would likely be gentler and not so aggressive.

 

Re: copper pick up tube.   I could give it a light pressure test with soapy water.

[Bloo]

 

 

49 minutes ago, MCHinson said:

If it is in similar condition to the 1938 sending unit that I worked on, you won't need to unsolder anything. I just needed to remove the rivets at the top, separate the two halves of the unit, clean up the windings and slightly rebend the "wiper" to give it a little bit more pressure against the windings and it worked properly.  

That sounds like a different type. On these the wiper is a spring loaded round cap over the end of a coathanger sized shaft. Unsoldering the shaft is necessary (on 1936-37) only if you wish to fix the cork brake that keeps the gauge from waving too much when the fuel sloshes.

59 minutes ago, 1937McBuick said:

I realize the shaft that the gear is soldered to is very small in diameter but couldn't a fine line be etched into it and the gear where they're supposed to line up(done before un-soldering the two)? 

It's nowhere near accurate enough. The goal with this system is to get to "zero" ohms, as if that were possible (what were they thinking?). You'll need to solder it with a multimeter connected and the float tied to empty. If there is any corrosion under the plate at the end of the resistor, the resistance won't go low enough and you'll need to make the wiper travel a bit too far so it slightly bumps into the washer. You really need to get this to less than an ohm with the float hanging. It probably takes more than one try. While you are soldering, the spring for the cork brake is trying to push the shaft out of the hole, and you can't let it over-rotate or come out of the hole too far either because if the wiper comes off of the resistor you get to drill the top apart and do that again. A tiny needle nose vise grip or two would be real handy. This part is annoying as hell, but I have done it successfully several times.

 

I'll look for those pictures over the next few days. I'm not sure they still exist. Feel free to bug me about it so I don't forget.

33 minutes ago, 1937McBuick said:

Re: copper pick up tube.   I could give it a light pressure test with soapy water.

Look at the 2 spots where the steel is crimped around it, that is where it will be cracked if it is cracked, especially the spot on top outside the tank. Silver soldering would fix it, but the units that have crossed my path had the tube all mangled so it was better to just make new. CuNiFer might bend easier. I've not tried it for this application.

 

Morgan: Sorry about the derail....

 

Edited November 13, 2022 by Bloo (see edit history)

[1937McBuick]

Sounds like a job that needs to be done without alcohol but needs a ton of finess and patience. 

 

Good thing I don't drink and can be finicky and patient.   I'd love to try this job but need to build some courage and confidence first.

 

I would really like to take a moment to thank the contributors of the AACA forum for their generous and freely given experience and advice.   My journey hasn't been easy,  too often I think about selling the project but I am into this(financially) way way too deep.  No one would pay me close to what I have sunk into it,  look what I started with but look what I have.   It's people like you that keep me going.  It's people like you that outweigh the shysters who sucked the life and fun out of it for me at times.   Karma works both ways,  everyone reaps what they've sown.

 

Thanks so much.....

[Rock10]

30 minutes ago, 1937McBuick said:

I would really like to take a moment to thank the contributors of the AACA forum for their generous and freely given experience and advice.   My journey hasn't been easy,  too often I think about selling the project but I am into this(financially) way way too deep.  No one would pay me close to what I have sunk into it,  look what I started with but look what I have.   It's people like you that keep me going.  It's people like you that outweigh the shysters who sucked the life and fun out of it for me at times.   Karma works both ways,  everyone reaps what they've sown.

 

Thanks so much.....

There are a lot of GREAT people here keeping these old cars running. 🙂

[DonMicheletti]

Here is the guts of my '38 Buick.

There are no seals other that at the electrical connector.

One of the things I'd expect as an issue is the ground (riveted end) of the resistor at the left side. and connection of the gage lead at the right.

There is a small spring type thing connected to the shaft and housing that should provide the ground connection to the wiper right behind the wiper arm (difficult to see in the 2nd photo)

 

Edited November 13, 2022 by DonMicheletti (see edit history)

[Bloo]

That resistor is the same as ones I have worked on, and matches what I wrote about above. The wiper ( @DonMicheletti 's second picture) is different on the 36-37s I have seen. It is a brass cup that goes over the tip of the piece that moves. A spring goes all the way around the curve and spring-loads the cup from behind. The spring has a tail at the bottom end that is riveted to the frame of the mechanism. The rivet is in about the same spot it is on this 38. and provides the ground.

 

[1937McBuick]

Question,    does it matter to the sending unit if the car's electrical system has been converted to 12 volts?

I think a resistor was installed near the gauge but will have to check to be sure.

[Morgan Wright]

I took a couple feet of extension cord and cut out around 10 strands of the copper wire. I wrapped them around and around the spot to be repaired, and when I got to the end of each wire strand, I ended by wrapping it up the rod toward the cork, so I can come back later and solder those ends to the rod so they can't unravel. 

 

I'll get back to you after I solder that.

Edited November 13, 2022 by Morgan Wright (see edit history)

[Morgan Wright]

This way none of the heat from the torch got too close to the fragile pot metal gear.

 

.

Edited November 13, 2022 by Morgan Wright (see edit history)