Stop that Stink!
The art of sealing a fuel tank
After months, possibly years, of going out into the garage and smelling gas fumes, it’s finally time to stop the seepage of gasoline from the old car’s fuel tank. Not only are these fumes stinky and messy, they’re downright dangerous. You’ve tried to find a new replacement tank, but no luck.
So what are the alternatives?
Fixing the old tank with a POR-15 Tank Sealing Kit is one very attractive and affordable option. We recently used the kit to fix the gas tank on a 1927 Chevrolet.
First, we drained and removed the old fuel tank. Depending on your application, that could be a simple extraction or a lengthy operation. Whatever your tank removal consists of, once it’s out and on the bench or floor, read the instructions supplied with the kit completely! That is the key factor to attaining a proper seal within the old tank.
The instructions read as follow:
Almost all fuel tanks are dirty and have to be cleaned out before sealing. It is very difficult to see the dirt and contamination inside the tank, but it’s there. In English, we call this bad stuff “gum and varnish,” and it’s almost always invisible to the naked eye. If you try to seal a tank without cleaning it first, the new coating will probably fail, because tank sealer won’t stick to gum and varnish.
1. Mix 1 quart of Marine-Clean with 1 quart of very hot water and pour it into the tank. Gloves and eye protection should be worn at all times. Shake the tank, and then place it in a different position every two hours so that the solution can cover all inside surfaces. When all surfaces have been subjected to the cleaning solution, shake it again, then dump out the tank, rinse it with water, dump out the water, and start all over again. The first time you dump the solution, it’ll be very dirty; after the second solution has been discarded; the tank should be clean. Rinse the tank out with fresh hot water, drain thoroughly, and then pour in the full container of Prep & Ready.
2. With the Prep & Ready in the tank, again shake, then place the tank in different positions every half-hour until the entire inside of the tank has been treated with Prep & Ready. Then rinse the tank thoroughly with hot water several times and drain it. In order to get the tank completely dry; you must blow warm air into it for a long time. No tank will dry out on the inside by itself. The only way to do this job is to use forced air. Tanks must be completely dry inside before sealing. The sealer will not stick to a damp or wet tank.
3. Pour in the entire can of fuel tank sealer and roll the tank around so that all surfaces come in contact with the sealer. Then drain for at least 30 minutes to ensure that sealer has not puddled in the tank. After you’ve done this, dump out the leftover sealer back into the can, but don’t put the lid back on the can tightly or it may explode! Leave the can open and it will harden overnight. Then throw it out the next day. Allow 72-96 hours for sealer to dry. Air dry tank in a well-ventilated area. Maximum cure will be reached in 96 hours. Setup time can be improved by using a low-pressure blower or hair dryer (low or no heat) and circulating it through one hole in tank and out another.
The best time to add patches on the outside of the tank is when you have finished drying the tank after using Prep & Ready, when the holes in the tank are too big to be sealed by the sealer alone.
Here’s how you do this: paint the area where the hole is with POR-15, then place a piece of reinforcing fabric into the paint. Now paint the cloth outward from the center with more POR-15. The next day, paint it again. You have now sealed the tank from both the inside and the outside. And remember, whenever you want to seal a tank, you must use Prep & Ready on the inside and/or the outside, because the adhesion must be perfect. After the tank is sealed, wait at least five days before putting fuel into it.
All the above at first might seem a bit intimidating, but it’s not as complicated as it sounds. And besides that, what if the fuel tank you need for your restoration is made of “unobtainium,” and your only option is to clean and seal the old unit? Now, all of a sudden, this process is not at all that complicated.
Thanks to our friends at Gary’s Rods and Restoration for their assistance in documenting the fuel tank resealing process on the 1927 Chevrolet currently under restoration.
Caution: Avoid making any sparks when working around gasoline! Follow all instructions to the letter!
1 Dissecting our project gas tank shows what can happen to the interior of an old leaking fuel tank. We were treated to this image because it was necessary to fabricate a new end plate for the 1927 Chevy’s fuel tank. Tank preparation begins with external sealing of the fuel drain and pinholes. Follow POR-15’s recommendations for sealing any pinholes.
2 Following instructions, a mixture of “very hot water” and the two cleaning solutions was applied.
3 After pouring our cleaning liquids and eventually the sealer into the tank, all tank openings must be plugged and sealed with tape, as seen here.
4 Rotation and waiting the required amount of time are mandatory for proper cleaning of the tank’s innards. The Marine-Clean and Prep & Ready must make contact with all interior surface areas prior to drying and sealing.
5 With the cleaning process completed and the tank completely dry, we poured the U.S. Standard Fuel Tank Sealer into the tank in preparation for the next rotation and final emptying steps. Caution: during the sealing process, any fuel drain or fuel pick-up tubes must be cleared with compressed air to avoid permanent blockage. Tip: cutting the bottom out of one of the empty Marine-Clean bottles makes a great funnel.
6 After the required 96 hours of chemical curing, our fuel tank was sealed and ready for gasoline. A “before” and “after” image with our Snap-On Visual Inspection Device (part no. BK5500) shows serious rust and crud buildup on left and a finished, evenly coated, sealed tank interior on right.