Gas tank flush and seal

[Wollfen]

I have a gas tank here out of Bob's Chrysler 300 coupe and I have been cleaning out the tank using diluted vinegar to remove all rust scale and deposits. This has been a very effective method and the inside of the tank showed up very clean and nicely etched.
Now, I was going to use POR15 fuel tank sealer on it but in reading on other forums it proves to be a second rate product in my mind. With that I did some more research and came up with the idea of using Red Kote tank sealer which has very good reviews on a number of forums. It is also reputed to be the same stuff that radiator shops use to seal the tank when you have them do the work.
Here is my dilemma, after I used the vinegar I had to soak the tank in rust dissolver as a final finish as the product is supposed to coat the tank in the short term against flash rust. But when I flushed the tank of the dissolver and let it dry it immediately got a coating of flash rust through the tank.
At first I figured this wouldn't be a problem with the Red Kote as it states it will seal in surface rust too. But upon reading the technical file on Red Kote it states that "Contrary to what some people will tell you, rust does form inside gas tanks. The causes are condensation in the tank and water in the gas. Red-Kote seals light rust under the coating so it cannot flake off to plug fuel-line filters or cause engine damage. Further rusting is also reduced."
I have now also read that radiator shops do not guarantee against further rust using this product.
So my question is this, should I bother with using the Red Kote? Can I just leave the tank and use it as is? There will always be at least half a tank of gas in the car at all times which should minimize further rust at the very least.
Tell me your thoughts, thanks.

 

[C Body Bob]

Hey Gary there's a bunch of videos on YouTube. Some are using POR15 others Red Kote. If you can spend a bit of time looking at those

 

[Big_John]

I'd leave it alone.

It's clean and it's not leaking.

 

[3C's & a D?]

It came from the factory raw and lasted fifty years, so after the good cleaning you gave it, it should be good for another fifty years. I have heard of the red kote turning into a jelly mess which of course clogs the pickup, when exposed to today's regular fuels.

 

[Fury Pursuit]

My .02

Keep the tank full always.

Use fuel stabilizer and non E85 gasoline.

Dump in two quarts of Marvel Mystery Oil directly in the tank and agitate it before installing the fuel tank into the car. Then fill tank with gasoline.

Then use Marvel Mystery Oil with every new fill up.

Conditions the tank and the engine. --- At a minimum it does no harm and keeps rust at bay.

 

[65sporty]

It looks good inside but I do like the idea of sealer. We got some one time that was a two part mixture but I can't remember the name. It was a dark blue/purple color when mixed. I got it from my local radiator shop.

 

[cantflip]

I'm just watching so I can steal your research for a couple of my own tanks... I want to coat them, but I really want the coating to ethanol resistant so I don't have future worries on the road and get force to refill with E15 someday.

Would ya hurry up? Geez, what have you been doing with all your time Gary...

 

[Ripinator]

I have a gas tank here out of Bob's Chrysler 300 coupe and I have been cleaning out the tank using diluted vinegar to remove all rust scale and deposits. This has been a very effective method and the inside of the tank showed up very clean and nicely etched.
Now, I was going to use POR15 fuel tank sealer on it but in reading on other forums it proves to be a second rate product in my mind. With that I did some more research and came up with the idea of using Red Kote tank sealer which has very good reviews on a number of forums. It is also reputed to be the same stuff that radiator shops use to seal the tank when you have them do the work.
Here is my dilemma, after I used the vinegar I had to soak the tank in rust dissolver as a final finish as the product is supposed to coat the tank in the short term against flash rust. But when I flushed the tank of the dissolver and let it dry it immediately got a coating of flash rust through the tank.
At first I figured this wouldn't be a problem with the Red Kote as it states it will seal in surface rust too. But upon reading the technical file on Red Kote it states that "Contrary to what some people will tell you, rust does form inside gas tanks. The causes are condensation in the tank and water in the gas. Red-Kote seals light rust under the coating so it cannot flake off to plug fuel-line filters or cause engine damage. Further rusting is also reduced."
I have now also read that radiator shops do not guarantee against further rust using this product.
So my question is this, should I bother with using the Red Kote? Can I just leave the tank and use it as is? There will always be at least half a tank of gas in the car at all times which should minimize further rust at the very least.
Tell me your thoughts, thanks.
View attachment 141159 View attachment 141160

Gary: I would go with the tank as is. Just tell Bob to remember to throw one ounce of marine 2-cycle oil with TC-W3 per five gallons of gas whenever he buys gas. Over time, that mixture will prevent rust and continuously clean all elements of the fuel system. The Marvel Mystery Oil is ok too, but it is very expensive when compared to the marine oil you can get at WallyWorld for $12.00 per gallon.

 

[Wollfen]

Would ya hurry up? Geez, what have you been doing with all your time Gary...

I know I know, I am slacking off, beat me with a a stick.

 

[65sporty]

I'm just watching so I can steal your research for a couple of my own tanks... I want to coat them, but I really want the coating to ethanol resistant so I don't have future worries on the road and get force to refill with E15 someday.

Would ya hurry up? Geez, what have you been doing with all your time Gary...

I did a google search and quite a few say they are ethanol resistant.

 

[saforwardlook]

Is a new repop tank available for the model you are working on - seems they usually are for a 300 coupe? Given the time you are spending and all, is that not a better option? I don't have fuel tank issues as long as the cars are parked inside, but then the humidity where I live is usually pretty low. So I don't have much elsewise to offer, but coatings in tanks never seem to be a long term solution from what I have heard over time.

 

[Wollfen]

I did a google search and quite a few say they are ethanol resistant.

They might be referring to this, it is a concern too, stopping the stuff from pooling after draining what you can may bring this about anyway?
" Not allowing the Red-Kote to dry completely. If RedKote is not completely dry or has puddles left it will form strings or flecks in the gas. These may get past the fuel filter and plug carburetors or injectors. Puddles of Red-Kote left behind baffles or in corners may never dry completely. This is because a skin forms over the puddles and prevents drying underneath. Once the skin ruptures the Red-Kote forms strings in the fuel. "

 

[cantflip]

I did a google search and quite a few say they are ethanol resistant.

Thanks, I have looked around in the past... I was hoping for someone else to be the guinea pig.

 

[Samplingman]

So what I gather from this is that the tank is not coated from the factory, why coat it now?

 

[C Body Bob]

So what I gather from this is that the tank is not coated from the factory, why coat it now?

Because it had rust in it & there's always that chance a bit is still tucked away & the possibility that the scale that came out may have been metal meaning the tank might be thinner in some spots. It's just an insurance. I'm going to leave it up to Gary to make the call.

 

[cantflip]

So what I gather from this is that the tank is not coated from the factory, why coat it now?

I'm pretty sure they started off with a galvanized coating. With nothing at all they would have rusted before leaving the dealer's lot.

 

[live4theking]

I'm pretty sure they started off with a galvanized coating. With nothing at all they would have rusted before leaving the dealer's lot.

I have to agree with them being galvanized. At least the old one I pulled sure looked galvanized.

 

[Big_John]

They are galvanized steel.

That got me to thinking and I did a little searching and from what I see, the vinegar will remove the zinc coating (which is what galvanizing is) after soaking for a while. It also produces hydrogen gas while doing this.

I guess the question is if the vinegar was strong enough and soaked long enough to remove the zinc. Most likely, given the age and then the bath, the coating is gone or close to it.

I'm changing my opinion and now I really think that coating it is a good idea and I think that the vinegar was the way to go to prep the tank for the coating.

 

[Samplingman]

They are galvanized steel.

That got me to thinking and I did a little searching and from what I see, the vinegar will remove the zinc coating (which is what galvanizing is) after soaking for a while. It also produces hydrogen gas while doing this.

I guess the question is if the vinegar was strong enough and soaked long enough to remove the zinc. Most likely, given the age and then the bath, the coating is gone or close to it.

I'm changing my opinion and now I really think that coating it is a good idea and I think that the vinegar was the way to go to prep the tank for the coating.

I wonder if Evapo-Rust would have been a better alternative to the vinegar in this case? Although expensive, I've had excellent results with E-R in the past even with heavily rusted metal, and it wont dissolve the zinc like vinegar will.

Another thought is that POR-15 will adhere better to lightly rusted metal. I'm wondering if the POR-15 prep was supposed to flash rust the surface by design to enhance adhesion? A side note, in my experience with the regular POR-15 coating, I have never used the metal prep and have had excellent results with the encapsulation, even leaving treated metal out side for years, with no further rust occurring. It was interesting to note that when I would grind off a section of the POR-15, the rust that I had left on was still there, but it was dry and lighter colored, again, encapsulated and stopped by design, not converted.

I'm assuming all of these processes work towards one goal, to stop the rust flakes from getting into the fuel system, and that we are just looking at different methods to that point, one not necessarily being better or worse than the other. It will be interesting to see how long the Red Kote will take to dry and if these "strings" form to get into the system. I'm hoping this works out and that we are just over-thinking the solution.

 

[C Body Bob]

I told Gary to let it dry as long as he felt it need with the one caveat that there's a hurricane bearing down on the east coast & Gary is a lot closer to the coast than I. So keeping any eye on things & leaving the possibility on the table that I may pic the car up Saturday & bring it inland. Other than that I'm in no real hurry. Too early to make that call right now.