A few weeks ago we replaced the gas valve in our '28 Sport Coupe because it kept letting fuel past and draining on the floor at night. When we did so we didn't have on hand one of those pencil filters to put in the tank. We bought one and will put it on. In the mean time the car has started to backfire quite a bit. (I know several other things cause that and we are in the process of going over those.) Last night we drained the tank and noticed that the firewall sediment bulb had a lot of sediment in it, so much so that the little screen was 3/4 full! Does that seem a bit excessive? Wondering how it all of a sudden got that bad. I'm hoping we don't have to pull the tank someday to clean it out, but maybe.... I'm glad we caught this before we drove to the Amanas next Saturday!
Fuel Tank Sediment
- Thread starter CatMan1
- Start date
rotorwrench
Well-known member
If the tank has internal corrosion then the terne plating is likely mostly gone now. Model A fuel tanks are a complex structural part of the car and they are not reproduced so owners should make an effort to evaluate condition and perform repairs based on that condition. Many DIY guys don't have the where-with-all to do major work on them so repair work is put off by performing measures that may stop the sediment movement but the tank continues to deteriorate until it corrodes through the sides or bottom.
Unfortunately, the only way to keep corrosion effects to a minimum is to keep the tank as full as possible with a fuel that has no oxidizer in it, ie no ethanol. This is not an easy task in the modern era.
The only way to stop corrosion is to completely remove the corrosion and seal the inside surfaces completely. Due to the complexity of the tank designs, complete removal of corrosion requires cutting the tank at the original seams to open it up to properly repair any damage and clean the metal for sealing. After repairs are completed then the tank is welded back together and then sealed 100% with a quality sealant. Needless to say, this is a drawn out repair action that takes time, knowledge, and skill.
These tanks were made from a draw quality steel that is close to 16 gauge thickness. This is near 1/16" thick since it was a structural part of the car. Even at this thickness they can and will rust completely through. Once that happens, any metal repairs become less and less possible due to how thin and porous the metal becomes.
Good original tanks are getting harder to source over time so take care of what you have to the best of your ability. Poorly derusted tanks won't hold the sealer so sealing one without proper preparation it is a waist of time and resources. Flaking sealer is as bad as flaking corrosion. I have a few tanks that would fall to pieces if it weren't for the corrosion still holding them together.
Unfortunately, the only way to keep corrosion effects to a minimum is to keep the tank as full as possible with a fuel that has no oxidizer in it, ie no ethanol. This is not an easy task in the modern era.
The only way to stop corrosion is to completely remove the corrosion and seal the inside surfaces completely. Due to the complexity of the tank designs, complete removal of corrosion requires cutting the tank at the original seams to open it up to properly repair any damage and clean the metal for sealing. After repairs are completed then the tank is welded back together and then sealed 100% with a quality sealant. Needless to say, this is a drawn out repair action that takes time, knowledge, and skill.
These tanks were made from a draw quality steel that is close to 16 gauge thickness. This is near 1/16" thick since it was a structural part of the car. Even at this thickness they can and will rust completely through. Once that happens, any metal repairs become less and less possible due to how thin and porous the metal becomes.
Good original tanks are getting harder to source over time so take care of what you have to the best of your ability. Poorly derusted tanks won't hold the sealer so sealing one without proper preparation it is a waist of time and resources. Flaking sealer is as bad as flaking corrosion. I have a few tanks that would fall to pieces if it weren't for the corrosion still holding them together.
BRENT in 10-uh-C
Well-known member
Good info from both of the above posts, but one other thing as a quick but effective short-term bandaid is to place some magnets (-think Harbor Freight) onto the back side of the tank to catch the floating metallic debris. Then when doing as Ronn suggested, remove the magnets and flush the tank. Then reinstall the magnets and go again.
Clem Clement
Well-known member
All my old cars had magnets outside the drain hole. On a friends car , we flushed the tank 3 times with evaporust. Still things were floating in the tank.
I could not remove the shut off valve. Gave up.
I could not remove the shut off valve. Gave up.
nkaminar
Well-known member
You can remove the tank and then flush it out with chemicals and use other chemical to seal the tank and prevent further rusting. Aircraft Spruce has the chemicals. See https://www.aircraftspruce.com/catalog/appages/gastanksealer.php?clickkey=7861
I had junk in my tank as well. I bit the bullet to preserve the tank for myself and anyone after me. I used the gas tank renu company process (https://www.gastankrenu.com/). Had a place about a half hour from me that did it. All other coatings will fail eventually. I'll never have to worry about that again. Was it a pain getting the tank out and back in? You bet. Did I have to repaint the tank? You bet. If I do another Model A, I'll go through the same process again. One less headache I'll never have to go through again.
Best of luck.
Best of luck.
Bob Bidonde
Well-known member
The gas tank is made of steel stock that has Terne Plating on one side which are the inside surfaces of the tank. Terne Plating is 80% lead and 20% Tin. The Terne Plating has 2 functions. It is electrically conductive, so it aided in the electric welding process used to manufacture the tanks. Terne Plating is also the corrosion protection for the gas tank. The Lead in Terne is chemically reactive to acid and base cleaning products, so choose your cleaning product and its time in the tank wisely.
I do not recommend the use of sealants of any kind in gas tanks because they have a history of delaminating and so contaminating the tank.
I do not recommend the use of sealants of any kind in gas tanks because they have a history of delaminating and so contaminating the tank.
BRENT in 10-uh-C
Well-known member
Sounds like you have a plan. From all accounts I have heard, Gas Tank ReNu does a great job but the issue I have heard repeatedly with them is they bore holes into the tank and then weld an unsightly plug back into the tank. They will tell you that you cannot grind the welds as it voids their warranty, ...which BTW, theirs is not a lifetime warranty unless both side of the tank are coated with their sealer. Why not do it the better way opening the tank in the factory weld? Lifetime guarantee that way.
.
Attachments
henry's 31
Well-known member
If you want a treatment that last go with Brent's method. Worth every penny you pay. He did one for me and I love his work.
years ago I bought a 51 chevy wagon. the previous owner used the RENU method. after 5 yrs the tank developed a pinhole leak in the rear corner.
so the renu process is not totally reliable.
fortunately, someone made a run of new tanks for the wagon and I bought one. can the old tank be fixed again- maybe.
so the renu process is not totally reliable.
fortunately, someone made a run of new tanks for the wagon and I bought one. can the old tank be fixed again- maybe.
Bob Bidonde
Well-known member
Brent, you do a fantastic job of restoring Model A gas tanks!