A look at gas tank coatings

Every now and then people post questions about gas tank repair.  At Eclectic Motorworks, we try to put in a new tank whenever possible as we see so many repaired tanks cause problems a few years later.  I recently cut a couple of repaired tanks open and I thought maybe you folks would like to see inside as well.

This is the inside of an MGA Twin Cam tank that had been thoroughly and pretty properly resealed by the shop that restored the car.  You can see they got the coating very evenly spread through the tank.

You can see how thick the coating is--somewhere around .100"

They got the coating in so evenly by drilling large holes in several places in the tank, then putting plugs in the holes, then letting the coating seal the plugs.  On the outside of the tank, they used body filler to hide the plugs. The trouble with this tank was that one of the plugs still had a pinhole which seeped under the body filler and then a big chunk came out eventually.  So even though this was done pretty carefully, it didn't last long.  By the way, a new MGA fuel tank is about $200, so it's a little surprising that this much work was done to save an old one.

This is the other extreme, and what we see more commonly.  This TR6 tank was done very poorly and the sealant didn't cover much.  To make it worse, the rust underneath wasn't properly cleaned away.  This car came in on flatbed several times, only to start right up when it came off the truck. The fuel filter was always pretty clean.  It turned out there were several 1" flecks of the black stuff floating around after they had broken away and every now and then they would block the fuel pickup.  After the car would get shaken around on the flatbed, the pickup wasn't blocked.

I don't cut many tanks apart, but look inside every one we replace.  If they've had coatings, they usually look more like the TR6 tank than the MGA tank. Ethanol seems to peel the coatings faster.  And that's why we usually install a new tank if we can get one.

Just thought I'd share. 

Very cool. Thanks, Carl.

Interesting, thanks for sharing. I don't have the wealth of experience that Carl has on this subject, but the information shared makes me even more glad I went with Moyer's in Pennsylvania for my tank repair on my Suzuki Cappuccino. New tanks don't exist, original or aftermarket.

Here's the inside of the tank when I got the car. It wasn't yet leaking, but brake and fuel hardlines under the car were leaking, and the rust flakes were causing problems elsewhere in the fuel system.

Moyer's cut the tank in half, blasted it thoroughly inside and out, then welded the two halves back together, then coated the inside completely twice, then put a heavy rubberized outside coating on super super thick. They guarantee the tank not to leak. Here's the end result:

Here you can see where they welded the tank back together:

And the exterior of the tank after treatment:

Just a satisfied customer and wanted to share in case someone else has a project where new parts availability is nonexistent...you don't have to throw the baby out with the bath water if the tank is rusty! 

I had Moyers do basically the same thing to a Toyota Starlet tank years ago. They drilled holes for the sealant and never cut it in half.

I didn't keep the car very long after I had it done, but I was impressed with the end result.