It’s gonna happen sooner or later … after 40 years of use rust particles will begin to form inside your fuel tank and you’ll need to restore it. Restoring the fuel tank can be done for $70 over a long weekend in an easy 4 step process: 1) cleaning & coating the inside of the tank, 2) repainting the outside of the tank, 3) replacing the old parts, and 4) checking electrical connections.
BUYING PARTS: From POR-15 (www.por15.com or 800 457 6715) buy their Fuel Tank Kit (below right) including Marine Clean (cleans residue & gunk), Metal Ready (removes the rust and leaves a zinc phosphate coating for the sealer to bond to), & US Standard Fuel Tank Sealer (forms a liner inside the tank filling-in any pinholes and cracks) for $53 total with shipping. From Home Depot or any hardware store buy four new bracket bolts (M8-1.25mm x 20mm) for $3 and Camper Mounting Tape (1.25” x 30 feet) for $5 which is a compressed foam seal for the rim of the tank. From your local VW supplier buy a new fuel tank kit (screen filter, gasket, nut, & tube for $8), fresh fuel hose ($1.50/foot), a 3.25” piece of fuel tank breather hose (10mm inner diameter), & a fuel sender gasket. A new Type III fuel sender will cost $75, so check your used one first (see “Testing Your Connections” paragraph). And get some rubber gloves to be safe. If you’d prefer not to do the cleaning & coating yourself, you can have a radiator shop do the work for about $180 + tax. It’s only money, right? It’s your choice.
RESTORING THE INSIDE: Remove the fuel tank from your T34 then remove the sending unit from the top and the tube fitting from the bottom (and the remains of what once was the cylindrical screen fuel filter). Add a metal chain (a handful of M8 nuts will do too) inside the empty tank and thrash it liberally to loosen off any flaky rust, then dump the debris out and you’ll be surprised by what’s been inside! Mine had leaves, a nail, lots of rust, a mostly-dissolved metal mesh filter, and even a petrified wasp (above)!
Day One: Combine Marine Clean with hot water in the tank for a couple hours to degrease, empty the brown sludge, rinse with the pressured hose, & let dry overnight. Day Two: seal off the openings with tape before pouring in the Metal Ready. This can sit all day if the tank is really rusty but it needs to be agitated regularly but no overnight treatments. I rotated the tank to cover all surfaces, let sit for a couple hours, then drained back into the container (reusable), rinsed with a gallon of hot water (not a high-pressure hose) and then let dry for several hours. Day Three: add the Sealer and rotate the tank to cover all areas. You’ve got 20 minutes before the goo begins to set, then drain and let dry 24 hours, fully cured in 4 days.
RESTORING THE OUTSIDE: While the tank is drying, remove the rust and old paint on the outside of the tank with sandpaper. Paint the exterior surfaces first in a rust-preventative primer and then with a couple coats of gloss-black premium paint. Paint the four tank brackets with silver for a new look. The tank will be covered anyway with the cardboard mat & vinyl lining, but it’ll look nicer and you’ll know you did a complete job. Finally, sand-down your old fuel cap and paint it glossy silver and add a couple coats of clear-coat.
While you’ve got the tank out, check out the condition of your steering box (see other article for details on this simple adjustment), tie rods, steering damper, master cylinder, & front brake hoses. Also remove the fuel hose in engine bay from the fuel line, attach a temporary hose and a bottle to it (to catch the debris&fuel from the line) and clean the fuel line with compressed air until you get clean fuel through: If the tank is rusty and dusty, the fuel line will be too as the lowest point of the fuel line is in the middle of the car.
These are difficult to reach when the tank is installed so it’s best to do it while the access is easy now.
After stripping off the old foam insulation from around the perimeter of the fuel tank area, cut the new foam strips and stick them into place (above). Leave spaces for the four mounting brackets.
Connect the new bottom drain metal tube & fuel hose before installing the tank. Once installed, connect the fuel hose to the main fuel line on the car. Install the new gasket under the fuel sender unit and connect the sender wire. Now you’re almost done.
TESTING YOUR CONNECTIONS: to check if your sender is working properly remove the sender wire from the sender on the tank and with the ignition key ON touch the sender wire to a ground bolt on your T34. If the fuel gauge needle shows a full tank then your sender connections are good.
Replace the sender wire on the sender and it should register on your fuel gauge if there’s fuel in the tank. If not then you may have a grounding problem. A bouncing fuel gauge needle is also a grounding problem. This is caused by poor grounding of the sending unit-to-tank or tank-to-body. You can spend an hour cleaning the electrical connections & metal contacts at the bolts, or you can simply run a short wire from the fuel sender to under one of the gas tank mounting brackets. This wire will be hidden by the cardboard tank cover as well as the trunk liner and the problem will go away.
Special thanks to Steve Makepeace, Ian Cuthbertson, Paul Stone, & Paul Colbert for their expert advice!