POR Problem

[Oldav8tor]

I recently had to replace my original 1916 round gas tank. the left end had been cut open by a previous owner and poorly repaired. When it started to leak last year I attempted a repair with JB Weld's Tank weld. It held a year but I pulled on a loose end last week and it pulled right off. Due to time constraints I ordered a new tank from Kevin Prus with the idea of eventually repairing the original.

Back in 2018 I had cleaned the tank using the POR 15 system. I was very careful to follow the instructions completely and made sure it was perfectly dry inside before pouring in the resin. It seemed to be holding up well.

Without going into details, I noticed the lining of the tank coming loose. Using a tool, I fished out several good-sized pieces of the lining (pix 1) which tells me it is coming loose within the tank. Fortunately I had modified my sediment bowl to accept a finger screen from a Model A (pix 2) or some of the lining might have drifted over the drain opening and cut off the fuel to the carb.

Perhaps others have had better luck but I won't be using the resin again.
Pix 1

Pix 2

[BRENT in 10-uh-C]

Tim, we are the largest restorer of Model-A Gas Tanks, and the only thing that we have found that will partially dissolve the coating is a 15% mixture of hot Sodium Hydroxide and water. Generally we soak the tank for a minimum of 12 hours in around 210° Sodium Hydroxide solution. Sometimes it softens it enough where it flakes off, -and sometimes it only softens it where it will need to be scraped out and then the remaining sealer can be eroded with media.

In all instances, when the urethane is found to be releasing from the tank wall(s), the issue is/was dirty metal underneath. Since we cut the Model-A tanks apart in the factory weld, we are able to access the entire inside of the tank. We generally use aluminum oxide to clean the metal and also apply a light texture in which the urethane sealer has something to easily make a mechanic bond. While I do like (-and use) the POR Sealer, we do not like their Tank Etch product as it does not provide adequate abrasion of the metal to create that mechanical bond for the sealer.

[schwabd1]

So Brent, what do you recommend to etch the tank?

[Oldav8tor]

Brent,
I'm sure you are correct....the most likely culprit is the preparation. I followed the instructions as best I could but could see only a small area of the cleaned tank through the filler hole.

Opening the tank as you describe sounds like the best approach....it certainly gives you the access needed to do a good job. There are commercial operations that restore gas tanks and in retrospect I should have availed myself of their services.

[Allan]

The etch primer comes after the tank is cleaned back to bare metal. I pour a couple of kilos of TEK screws into the tank and set it up in a concrete mixer to rotate it until the tank is cleaned back to BARE metal. The mixer allows the tank to be tilted to concentrate the screws at either end until the job is done.

I have used the POR system on three tanks over the years, and still have not had a problem. One kit was used on my home made fuel tank in my speedster, to seal some pinholes in my welds! I didn't like the idea of welding on a tank that had had fuel in it recently.

I have never used ethanol blended fuel, if that makes a difference.

Allan from down under.

[Jerry VanOoteghem]

Tim,

Several years ago, I took the gas tank from my '24 Buick to "Gas Tank Renu". They cut it open, cleaned it, and coated it. That was probably 20+ years ago. It wasn't too cheap, but finding a great gas tank for a 1924 Buick was not a great prospect. A new Model T gas tank would be cheaper, but if you really want your particular tank restored, it may be an option. Be sure to tell them to not coat the exterior, which they would normally do, and to mask the threads for the filler cap and sediment bulb.

https://www.gastankrenu.net/

[Henry K. Lee]

Prep is the key! For years I only used Evapo-rust solution twice, rinse with warm soapy water, rinse again with just warm water. install a new bag and filter on a shop=vac, reverse the suction port with exhaust and purge for about 2 hours rotating the tank multiple times. Install about 2 quarts of Red-Kote and rotate all around and pour out. Let dry for two days before using. 30 years later..., never a problem!

[JTT3]

Hank you are spot on, Red Kote is a great product if you let it cure til it doesn’t have a strong smell to it. I have a metal funnel from a decade ago that I used to pour the Red Kote into a tank, the funnel still has the coating on it. With your military discount you can get a gallon for under $100. I have cut Red Kote 50/50 with acetone to coat the inside bowls of carbs & corks. Works like a charm once cured. Best John

[Oldav8tor]

I've had others suggest putting something in the tank and mechanically cleaning it. One fellow I know ties the tank to a tractor tire and drives it for awhile. I thought of doing something along that line but not knowing the clearance around the baffle I was reluctant to do so. It's one thing to put stuff in, another to get it out. In retrospect, I should have persevered.

Gas tank renu is expensive, but new tanks aren't cheap either. I'll eventually do something with the original tank. The need to repair the one end is an excuse to open up that side and see what's really going on within the tank. In the meantime, it's great that we can still get new tanks.

[mbowen]

Tim, I had a similar issue a few weeks after I bought Bonnie, my touring car.. I came home from a week-long vacation to find a hangar full of gas fumes and an empty tank on the T. I removed the tank and found a few pin holes around the outlet bung, which I (safely and successfully) soldered closed. I then decided to add a belt to the suspenders and, like you, did the POR 15 treatment, following the instructions to the letter as best I could, using several pounds of small nuts, bolts, screws, and ratchet sockets along with the provided cleaning solution. To make sure it was dry I used an old hair dryer with a plastic nozzle just the right size to thread into the filler neck, which I ran overnight to make sure the tank was completely dry. I managed to get a flexible borescope past the baffle, and all I could see was clean metal throughout. I then applied the resin and let it cure for the prescribed amount of time in the prescribed temperature range.

Everything was fine for over a year and a half, when I pulled the engine for rebuild. Three months later, with only a very few miles on the rebuilt engine I started having surging and stalling problems, with symptoms similar to vapor lock. A few minutes after the engine would quit I could start it and drive another mile or two before it would quit again. To make a long story less long I discovered that the sediment bowl was filled to the top of the screen with thousands of little silver “nuggets” of POR 15 resin, no sheets, just little nuggets. After removing and thoroughly cleaning the sediment bowl the car ran fine. I continued to get more POR debris in the sediment bowl for months, but it finally tapered off to the point where now I only check it when I’m under the car for something else and only get very tiny amounts. I’ve never completely drained the tank to borescope it again, but what can see from the filler bung, the coating is completely intact, so I assume I didn’t get the area on the other side of the baffle as clean as I thought I did.

I too won’t be using POR 15 again, not necessarily because it’s an inferior product, but mainly because I have no way to be sure I’ve gotten the entire tank clean enough for it to adhere properly.

[bobt]

A pound or more of one inch long drywall screws yes, drywall screws. They have sharper edges and points. Add to the screws and a squeeze of BLUE Dawn dish washing soap to the and about a gallon of water to the tank and shake and rotate and shake and rotate and then shake and rotate some more. Check your progress by checking some of the water you dump out between shaking. I Did this intermittingly for about three days and then followed the POR directions. I then dried the inside of the tank with the reverse shop vac for hours. It took me about a week to do the whole process and the POR worked GREAT. bobt

[BRENT in 10-uh-C]

So Brent, what do you recommend to etch the tank?

Aluminum Oxide media. To do the job correctly, the surface needs to be abraded so the urethane has a mechanical bond. Once the insides have been thoroughly blasted, the tank is fixtured and rewelded.


.

[John Codman]

Allen - I absolutely agree with you about welding on a tank that has had gasoline in it. The problem is what do you define as recently? I was a High School Teacher and had a student - at his workplace - Attempt to weld a crack in a 55-gallon drum. It had been stored inside for a year with the vent and fill plugs removed. They moved it outside and filled it to overflowing with water. They then let it dry for a couple of days; my student started welding and the tank immediately exploded, killing him. If I were going to weld a tank, I would have it filled with nitrogen or another inert gas first.

[varmint]

I used the POR system and am fine with it. However, I recall prepping the tank (improved & made from unobtainium) with vinegar and rocks for weeks. The tank was then rinsed out several times before POR began.

[tdump]

all i can say is do not use that red kote if you use Star tron or Stabile in your gas. they will desolve the red coating and it will get into your carburetor, and worse. you can google it and read storys of restored tractors having to be torn back down because of stuck valves and such from it. and even the company will tell you don't use star tron.
how else would we preserve gas in something that sits alot without additives?

[JTT3]

Drain it, just a thought.