Hi all, First time posting, have enjoyed the archives though. So , I have had quite alot of difficulty finding a suitable replacement gas tank for a 78' coupe. I have seen 6 of them and upon closer inspection, all have split bladders. The material is High Density polyethylene and apparently decays over time and causes these splits. My question is : Is there an epoxy that will repair these bladders that will obviusly need to be impervious to gasloine? I understand that this materieal can be "Spin-Welded", however that necessitates cutting the tank in half and welding the bladder and then trying to re-weld the tank shut without damaging the plastic. Probably impossible. Anybody have any thoughts? GM has discontinued theses tanks and i cannot find an aftermarket source. Thanks in advance for any help!
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Re: 78-82 Gas tank
"Delray"-----
These 78-82 fuel tanks are going to be a major problem for 78-82 owners unless someone comes on the market with a reproduction. Due to product liability issues, I'm not hopeful that this is going to happen any time soon, if at all.
As you descibed, these tanks have a steel sheel with an integral bladder. The bladder is of a polyethylene or polypropylene material. Like all organic material, it will be eventually degraded by contact with an organic solvent, in this case gasoline. Personally, I think that once the degradation occurs, the bladder is not really worth repairing, even by the method that you suggest. This method will be difficult and, likely, expensive if even you could find someone to do it. If it were a PERMANENT repair, and considering the unavailability of new tanks, it would be worth just about whatever it cost. Unfortunately, I don't think that the repaired bladder would last very long before further degradation and leaks occur.
The 75-77 tank has recently come onto the market. This tank originally used a seperate steel shell and bladder. However, in reproduction, only the steel shell is available. Presumably, someone could use just the steel shell and omit the bladder. That arrangement would be no more dangerous than any of the 63-74 tanks, but I really don't think that anyone would be found recommending such a thing. The fact is, when one DEGRADES or RECOMMENDS DEGRADING a vehicle from its ORIGINAL safety condition, very serious concerns and issues are raised.
No reproduction of the 78-82 tank is currently available. Although the 75-77 tank SHELL has become available in reproduction, the part was originally supplied in that form from GM. The fact that no bladder is available for this tank is entirely INDEPENDENT of the availability of the shell and no liability issues are created. In the case of the 78-82 tank, the bladder and shell were INTEGRAL. Therefore, I don't see anyone coming out with just a bare shell without the integral bladder for liability issues. And, since even reproducing the original configuration tank carries with it difficult, and likely EXPENSIVE, product liability issues, I think that won't happen soon. But, I hope that I'm wrong. Because if a reasonable and safe replacement is not made available, then I'm sure that folks will start implementing "less safe", "bubba-ized" solutions to keep 78-82s on the road.In Appreciation of John Hinckley -
Re: 78-82 Gas tank
Thanks for your reply Joe. Doesn't sound like many alternatives exist. Like i said, i have viewed several of these tanks in my quest to find a good one and have not been successful. I would expect that the vast majority are already split, and leaking between the bladder and the outer steel shell. I suppose if i use one of these, i am in no more danger than any other 78-82 driver out there. I do believe that new vettes use an ABS plastic tank, and may be the solution however, as you pointed out, that deviates from the "design" Chevrolet originally intended. I can only hope for the best but i am not optimistic! As an aside, thanks for hours of great reading as i have read many good discussions in the archives.
DonComment
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Re: 78-82 Gas tank
What is the purpose for the bladder? Could we use aviation technology for this. They use a rubberized liquid to seal the tank on the inside.
Signed No leaks yet.Comment
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Re: 78-82 Gas tank
Well , that was my question. If i can remove the bladder from the tank, in several pieces obviously, then why couldn't i get the tank sealed and use it as a normal gas tank. Sounds reasonable to me..Comment
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