Gas Tank Repair

[MikeC5]

My 25 touring car gas tank has a few dents and some very nasty stuff inside (50 year old gasoline remnants). I'm not sure if it has a baffle; none I can see from the gas gauge port. Has anyone taken the end cap off? It must be soldered on but it's hard to be sure. Any tips?

[Guest 1930]

I wouldnt try that, fill it with some water ( maybe 3/4 full ) if you like and then pressurize it with air, work the dents out.

[platt-deutsch]

I did the tank on my 25 with the POR15 tank sealer kit. It did a super job and I did it exactly like the directions said. The Marine Clean product cleaned the inside to shiny metal. Then I poured in the quart of sealant and rolled and turned the tank for about 10 min then drained out all the excess . I then hooked a hair dryer to the gas guage bung and let it run overnight. The sealant hardened like glass and inside is now perfect. Never seen a product like it..!!

[R.White]

this could be of interest:

If you want to be sure that the sealant will last a very long time, you could use Tapox which is 100% ethanol proof. and available on Ebay. (POR15 is O.K. up to 10% ethanol) This is what I used but I expect it is quite a bit dearer. You pays your money and takes your choice!

Ray.

Edited April 10, 2012 by R.White (see edit history)

[billstewart]

Hi Mike , after I cleaned my tank I used fibberglass rasin ,and turn it around and around. then let it dry. I've done this on model a,s and t,s for years, never had any problums. Bill

[60ch]

If your tank is constructed in the same fashion as the 29 DA the long seam is a standard Pittsburgh locked seam and the oval end caps are also folded in on each other and crimped. The seam at the top is sealed with solder along its length and the end caps are also sealed. The only way to take it apart is to cut it apart. Even if you did melt the solder it would not come apart because of the locked seams. Unless you are experienced in fuel tank repair don't attempt to remove the end caps. Terry

[MikeC5]

Thank you for the tips guys. It sounds like taking it apart is not a good idea. I'm a little concerned about using sealer only if there is a baffle in there that prevents full coverage (or getting baffle surface itself sealed). I'm going to bring it into work and take a look with a borescope and see what I'm up against.

[Guest 1930]

Little dental mirror would do the trick, I doubt there is a baffle in there but never owned a 25 either so you tell me.

[MikeC5]

I just did a quick check by poking some stiff wire in there and sure enough, there is a baffle a little past midway from the filler end. There are some spot-solder joints at the same location which I thought were most likely repaired leaks. I will try the mirror trick too.

[Guest 1930]

I just did a quick check by poking some stiff wire in there and sure enough, there is a baffle a little past midway from the filler end. There are some spot-solder joints at the same location which I thought were most likely repaired leaks. I will try the mirror trick too.

Thanks, I dont remember seeing one in my Dodge but maybe I am just forgetting

[R.White]

Hi Mike. You may be surprised at just how much rust there is in your tank. Originally, tanks were made from lead coated steel (aka tern plate) but they do rust eventually. I found that when I started to clean out my tank, small rusty flakes kept appearing. A few nuts rolling about got rid of the worst of it. I repeated the process again after I had applied the rust converter and eventually got to the stage when I felt it would be O.K. to add the sealant. (It goes without saying; get all the nuts out)

The sealant will completely cover every part of the tank interior - including the baffle but you do need to give it a thorough tumbling. Also, the sealant should happily fill in the odd pin prick hole.

One other thing; when you blank off the openings, screw a suitable bolt into the threaded hole for the fuel pipe to save the threads from getting bunged up.

Just some thoughts as I have just done mine with Fertan rust converter and Tapox tank sealer which is 100% ethanol proof but quite expensive.

Ray.

[Guest 1930]

Also I have found that because of the thickness of the gas tank sealer you may need more than you think. dosent seem to go very far in other words, stick the can on a stove burner for a few minutes or out in the sun for a few hours to warm it up so it flows easier.

[MikeC5]

Thanks for those tips guys. I like the idea of adding objects to enhance the scrubbing action. I wonder if gravel would work well?

[Guest 1930]

A chain works very well but I have heard of guys using gravel

[billstewart]

Hey Mike I filled mine with lye and water and let it set for a couple of days, then washed it out. It shined like new. I let it dry acouple of days then did the fiberglass rasin. There is some around that I did 30 year a go still doing fine,Bill

[R.White]

Hey Mike I filled mine with lye and water and let it set for a couple of days, then washed it out. It shined like new.]

Just a little language difficulty for me.....what is 'lye'.

Could you use molasses? :cool:

Ray

[billstewart]

Hey ray, lye is a alkaline, it what they used to make lye soap out of. They used to make it from wood ashes, you can buy it in stores they sell it as a drain cleaner now. Bill

[R.White]

Ahh! We know it here as caustic soda or sodium hydroxide.

What do you think about using molasses as an alternative? Would it be as quick or as good?

Ray

[billstewart]

I will try molasses the next time , I just recently heard about molasses removing rust.I bet it will do a good job. Bill

[Guest Bill Miller]

I kind of hate to throw a monkey wrench in the works but my experience has been that gas tank sealers, epoxies, etc. just don't last. The problem is modern gasolines end up eventually eating up the sealant, even hi-tech epoxies, gumming up your fuel lines and carburetter. In this country the EPA in its wisdom has prohibited the use of compounds which really do work and do the job right. Having said that, there is a fellow in Quebec who has a company called Monsieur Reservoir if my memory is correct. In Canada they can use all sorts of stuff to clean out and rebuild gas tanks that we cannot use here. Try calling Pierce Reid or Bill Cooke in Stowe, VT, who run a first-class mechanical restoration shop mostly working on Rolls-Royce / Bentley prewar cars. But Pierce has a Model T and Bill has a Stanley steamer so they are quite knowledgeable with most aspects of the antique car business and hobby. They know how to get in touch with this guy and can take care of any final finishing of pinholes etc. on the tank once it comes back.

[R.White]

Absolutely right, Bill. The more ethanol that they put in the petrol, the worse it attacks most tank sealants which is why I decided to use Tapox which is 100% ethanol proof. The makers insist that all existing sealant must be removed first. Tapox tank sealant is made in Germany but whether there is any restriction of it's use in the U.S.A., I simply don't know.

The irony of using all this ethanol in the petrol is that it actually reduces our m.p.g. So instead of helping the environment, it ends up doing more harm than good!!

End of rant!

Ray.

[MikeC5]

I do have my doubts about the sealer route too Bill. I'm going to talk to a local radiator/gas tank repair shop and see what they say. I did pour a a quart of laquer thinner in there tonight and sloshed it around, let it sit for a day. I haven't seen any evidence of leaks yet...

[MikeC5]

No leaks as far as I can tell.. (the lacquer thinner did not evaporate since I had all openings taped). Ray, I did some web searches on Tapox but it appears it is unavailable in the U.S., nor is it legal to import (according to one vendor). Must be some good sh... uh, I mean 'stuff'.

[1936 D2]

These are some examples of current things available here in the USA:

Fuel Tank Sealer, Gas Tank Sealer, Hirsch Tank Sealer - HirschAuto.com

and:

FUEL TANK REPAIR KIT-POR-15 Inc.

and:

Auto Gas Tank Sealer Kit - Gas Tank Sealer - KBS Coatings

and:

Caswell Epoxy Gas Tank Sealer (Car Tanks - Up to 20 Gal) 1 Quart - Caswell Inc

These are just SOME of the listings from a Google search. Some have evaluations, some have studies done concerning chemical resistance against numerous items. You would have to evaluate the results for yourself.

[1936 D2]

I was going to ask a question here concerning previously sealed tanks. I have a tank I sealed with a "kit" tank sealer about 28 years ago. The tank has never been filled since. I believe the color of the sealer was a light mint green as I recall. There was NO ethanol gas then so that was not an issue. Others that had used that formula reported later that they had problems with the sealer in ethanol gas. These reports were coming out fairly quickly after the introduction of ethanol gas. So, now I have a tank fully sealed but with the wrong product. I was going to ask if it could be directly sealed over with the new ethanol resistant sealers, but while reading some of the pages in the above links, I found that they pretty much all say that the old tank sealers should be removed before using the new ethanol resistant sealer. They did not say why. It could be because they are assuming the tanks were USED with the old sealer and were having issues. In this case they say to remove the old so their product will work better and not rely on the seal from the old stuff. I'm pretty sure there are not many tanks that have sat around for 30 years unused and needing the new sealer.

Maybe I should let it sit another decade and see what they do to the fuels by then! (NOT!)

So, what do you think, seal over it directly with the new liner - assuming the original brand new unused liner is well connected to the interior of the tank?

Use Acetone to try and remove the old before resealing?

Use Methylene Chloride (a paint stripper) to remove the old liner?

Opinions please...

[1936 D2]

Hey MikeC5 - If you DO get a chance to check that tank with a scope at work, could you possibly record that and put it up on YouTube? I think many of us would be curious to see what the inside of an older used tank looks like!

Thanks!

[Guest 1930]

No leaks as far as I can tell.. (the lacquer thinner did not evaporate since I had all openings taped). Ray, I did some web searches on Tapox but it appears it is unavailable in the U.S., nor is it legal to import (according to one vendor). Must be some good sh... uh, I mean 'stuff'.

If it were my tank I would not have put laquer thinner in it, dip a piece of bare steel in laquer thinner, pull it out and let it sit for a few minutes, watch what happens.

[R.White]

Ray, I did some web searches on Tapox but it appears it is unavailable in the U.S., nor is it legal to import (according to one vendor). Must be some good sh... uh, I mean 'stuff'.

Well Mike, where you guys go; we follow. Guess I had better stock up before it's too late!

[Guest 1930]

Well Mike, where you guys go; we follow. !

Your in for some real trouble if thats the case

[R.White]

the old tank sealers should be removed before using the new ethanol resistant sealer. They did not say why.

I would think that all you need is a sound surface. So long as the new sealer does not react with the old, my guess is it will be fine.

Ray.

[MikeC5]

Lacquer thinner is just a de-greaser/cleaner. It usually does a very good job so things will get some flash rust if in a humid environment. I wanted to see if it will dissolve the black, hard, used-to-be-gas stuff in there.

[R.White]

A number of products which are available in the U.K. may or may not be allowed by U.S.A. authorities but anything which is endorsed by the FBHVC can be relied upon.

After exhaustive testing and research some fuel additives are available in the U.K.

I hope the following is at least of interest.

FBHVC Blog Archive FUEL STABILITY ADDITIVE TEST RESULTS

[1936 D2]

Holy cats Jason, your signature is getting longer than your posts!

[MikeC5]

D2, I will get photos and maybe some video when I get the scope in there. I'll share the results for sure.

[1936 D2]

Excellent! MultiMedia - a wonderful world!

[Guest 1930]

I guess I had forgotten there was a baffle inside of the 29/30 DA tank, here it is.

[Willy]

1930, I too, have (some big) dents in my gas tank. I like your post about putting water in it. I assume I need to plug all holes but one, and how much air should I put in the tank? I thought about drilling a small hole, and use a slide hammer to get some out, but don't want to add more holes. When you said, "work the dents out", how do I do that?

[Willy]

Does anyone know if a gas tank from a 1924 DB Touring will fit exactly in a 1918 DB Touring?

[Machinist_Bill]

Willy, Here is a scan showing the same tank used from 340069 until car 929894 (116" Wheelbase). Part Number 6887 for Touring.

[MikeC5]

I had the tank cleaned out by a local radiator repair place and he said it appears to be quite sound. I soldered a new pick up tube into the original fitting so it should be good to go. I will take a look on fleabay for the Tapox just in case...