VCCA Home Forums TECHNICAL - 1945 AND NEWER 1971-1979 1975 Corvette Fuel Tank Bladder

Are there any failure issues with these bladders? The increasing alcohol levels in fuel have got me wondering about the life expectancy.

My car has only had about 5000 miles put on it in the last 25 years and I've kept it VERY, VERY FULL with stabilizer, some 2-stroke oil (car has true duals / no cat) and usually a quart of alcohol every fall to deal with any moisture but I plan on discontinuing adding the alcohol since there's now more in the fuel.

I've never had to touch the carb and it starts and runs great so it seems this process has been working well...so far. Anything that can be done to take care of this bladder?

Thanks

Tim

That is a good questions I know on some of the older cars the alcohol eats the rubber up good. Your in Canada? How much alcohol is in your gas? Is it more than 10% I would avoid anything over 10% in the gas.
I live in Texas and so far the only gas that seems are at least it shows on the pumps with alcohol is at large trucks stops showing 10%. In my older corvette I stopped using that when I seen it on the pump, because it might eat my rubber hoses up. But even at that small amount we might be safe, just be cautious .

Canada indeed. The percentages are about the same as the US - in "normal" regular gas it seems to be 10%Alcohol, mid grade less, high octane is less again. There is "gasohol" out there but I've never paid much attention to it. We just get to pay more for the gas but it's no different. We're getting a huge deal right now since the price of oil has droped; about $4.25 a gallon.

There were several percent in gas during the winter when I was a pump jockey 30 years ago. Not sure if it was to eliminate pump feezing at the stations or to prevent cases of "my car was fine before I bought YOUR gas"...maybe both.

At least your '71 has a normal steel tank. The bladder in my '75 has performed well but I wonder what the life expectancy truly is?

Hi Tim,

Coming to this party a little late - but I could not resist the temptation to reply.

The fuel tank in a Corvette is one of the easiest to inspect for condition - thanks to a huge filler neck. You can put a mirror inside and look around.

If condensation is a concern - jack up the front of the car - and suck out the fuel at the bottom rear of the tank - the water will roll to the back (if there is any)

A few months ago - I took some fuel samples from several stations in my area. The purpose was to confirm the alcohol%
I was impressed to find the most at 5% - well below the 10% posted on the pump sign. Most likely, they are keeping it low - to prevent the % from going over the 10% allowed by law in certain states.

How long do they last? I have some tanks in my collection that are 40+ years of age and they look new inside.... I use STABIL year round and like you - keep the tank FULL.....

FYI,
Stabil has alcohol as a major component. I did not realize that until it ate the diaphram in a '31 fuel pump. I say ate but actually turned it into a black goo-like jelly. Since have changed all diaphrams to alcohol resistant material.

Thanks guys,

I hadn't thought about looking inside the Vette tank until after I pulled the tank from my 38 but by then I had it filled to the brim with Stabil added. I went heavy on the stabil too but it's still probably not much more than a cup in a full tank. Good to be aware of the alcohol in the Stabil.

Next year I'll take a good look inside that tank since it is indeed so obvious!

Thanks