There's more reason now than ever to protect your petrol.
Gas tanks have become a subject of interest recently because of how much it costs to fill our tanks. As our Corvette's go-juice becomes more precious, it's appropriate to examine the hardware that holds and protects the gasoline. The tank itself is mostly hidden from view and keeps a fairly low profile in the maintenance category. Primary reasons for replacing a Corvette gas tank are rust damage (from inside or out), collision damage, and cosmetics (as in restoration).
The appearance of rust damage on or in gas tanks is a puzzler to some people. The tank was unpainted from the factory, but the silver-colored sheen of its surface looks somewhat similar to galvanized or galvanic plating. And the surface acts like it has some form of rust-preventative coating-entire areas can be rust-free, even though adjacent areas suffer from extensive corrosion.
Extensive rust is evident on the exterior surface of this New Hampshire Corvette gas tank.
The name of the coated steel used for gas tanks is Terne steel. This type of steel was primarily selected because of how the upper and lower halves of gas tanks are made. Each half is pressed from a flat sheet of Terne-coated steel. More specifically, each half is deep-drawn and the lubricity of the coating helps the steel slide on the tooling as the steep sides are formed. Terne steel has a dull gray finish from its coating, which consists primarily of lead with a little tin. Another attribute of this particular coating is it provides good corrosion protection when in contact with petroleum fuels.
Original Corvette tanks were made of Terne steel and had no zinc (galvanize) or nickel coatings according to Gary Whiting, president, Quanta Products LLC. The Quanta reproduction tanks are made with Ni-Terne steel, which has an additional flash coating of nickel applied to the steel before the traditional Terne steel lead-tin coating is applied on top. The underlying nickel coating provides a greater measure of corrosion protection.
We cover what's involved in removing and replacing a C2 or C3 gas tank and its related components.
For those readers who don't need to replace their tanks, there's a sidebar above on how to easily vacuum water and debris from the inside of the tank. This prevents corrosion or rust-through from the inside and helps keep down-stream parts, such as the carburetor and engine, clean and happy.
|Difficulty Index - 2 Wrenches|
|Anyone's Project: no tools required||1 Wrench|
|Beginner: basic tools||2 Wrenches|
|Experienced: special tools||3 Wrenches|
|Accomplished: special tools and outside help||4 Wrenches|
|Professionals Only: send this work out||5 Wrenches|
|Things You'll Need |
|Gas tank ||$219 |
|Anti-Squeak Strips ||$5 |
|Hold Down Straps ||$40 |
|Sending Unit ||$70 |
|Gas Cap ||$30 |
|Overflow Kit ||$48 |
|Hose and clamps, tank to fuel line ||$7 |
|Hose and clamps, tank to separator ||$7 |
|Hose and clamps, separator to vapor line ||$7 |
With the body-off, it's easy to see how the front of the tank rests on a removable crossba
The rear framerail supports the rear of the tank. Although this is a custom frame featurin
The tank is one of Corvette's bigger parts, but it still can be shipped to your door. Quan
The antisqueak strips are likely to need replacement, and a pair only costs $5. If your ho
The gas tank sending unit has an internal coil of resistance wire that can eventually brea
The sending unit is held in place in the tank by a lock ring; a rubber seal goes between i
Parts located on the top of the tank include the overflow boot, nipple, drain hose, hose s
After draining the gas tank, remove the spare tire carrier and cover. Use caution when rem
Slide the clamps out of the way, and then carefully break the hoses loose. If the hoses ar
If there's a fuel-vapor separator on your tank, it's located on the top left side. Althoug
Oil the exposed threads and remove the bolt from each hold-down strap. There's no need to
Remove the four bolts that attach the tank crossbar to the frame. A 9/16-inch box wrench c
Two tabs determine the alignment of the sender in the tank. Press the sender against the r
The threaded holes for the filler neck screws open into the tank, so make sure the o-rings
There's nothing tricky about the installation; it's just the same steps in reverse order.
Some areas of this tank are completely rust-free, while other areas are heavily rusted. Th
The '75 Corvette model year introduced a gas tank with a reinforced rubber bladder to redu
If your tank is original, there may still be a buildsheet (tank sticker) glued to the top
Tank Maintenance-Vacuum Water and Debris
Inevitably water and dirt get into a gas tank. Dirt that passes the fuel strainer can cause problems with everything downstream, from the fuel pump valves to the carburetor, and, ultimately, cause engine problems. The effect of water on these parts can be just as bad or worse. water is heavier than gas and settles into the lowest part of the reinforcing channels stamped into the tank, which can cause the tank to rust-through from the inside. Fortunately, it's fairly easy to remove any water and dirt from a gas tank of a '63 to '74 Corvette by using a length of hose and a small metal tube.
Attach about eight feet of transparent 1/4-inch rubber hose to a 1/4-inch brake line that'
Insert the tube into the tank and position it in the front of one of the recesses at its l
Start the siphon to vacuum the water and dirt from the tank. Tip: bump the car slightly to
A few minutes of gas tank maintenance can prevent future problems by removing water and di