'78 - '82 Fuel Tank Sealant

[Kenn S.]

So I'm cleaning up the tank for an '80 car, getting ready to re-install it on to the frame. For some reason I can't recall, I grab a flashlight and just check things out on the inside before I go too much further. And wouldn't you know? The bladder has a crack. The outside of the tank is perfect...no dent. But the bladder looks like it was dented at some point. The location of the dent leads me to believe I didn't kill it when removing it, which is gratifying but not satisfying.

Naturally I come here and research, only to find that tanks for '78 - '82 cars aren't reproduced. Seriously? Yes, seriously. I checked. So we're left to find a used tank--good luck getting that shipped with no bladder cracks.

The situation is exacerbated by the fact the bladder is going to dissolve over time simply because of contact with gasoline. Mine, from what I can tell, isn't too awful bad in that regard, save for the cracks. But imagine...GM putting a bladder material in a fuel tank that dissolves in gasoline. Go figure.

Here's my plan, and hopefully anyone else in the same situation will find it helpful if the plan is solid. Step 1 will be to fill the cracks with Permatex fuel-impregnable gasket sealant. That'll fill any big gaps. This stuff is readily available at any auto parts store. Step 2, however, is the new tech out there, Red Kote:

http://www.dimecitycycles.com/red-ko...ler-liner.html

This may not have been available when the postings in the archives I found were written. But it looks really good, from what I can tell. I'll call the merchant and ask about possible use in a bladder-lined tank, but I suspect it'll work just fine. If anyone's interested, I'll post what the merchant says here in a couple of days and follow up with the repair results. If it works, it'll not only fill cracks and gaps but also solve the dissolving bladder issue.

Damn sight better than scrapping the car.

Plan seem solid? Surely seems worth the try.

[Joe L.]

Re: '78 - '82 Fuel Tank Sealant

So I'm cleaning up the tank for an '80 car, getting ready to re-install it on to the frame. For some reason I can't recall, I grab a flashlight and just check things out on the inside before I go too much further. And wouldn't you know? The bladder has a crack. The outside of the tank is perfect...no dent. But the bladder looks like it was dented at some point. The location of the dent leads me to believe I didn't kill it when removing it, which is gratifying but not satisfying.

Naturally I come here and research, only to find that tanks for '78 - '82 cars aren't reproduced. Seriously? Yes, seriously. I checked. So we're left to find a used tank--good luck getting that shipped with no bladder cracks.

The situation is exacerbated by the fact the bladder is going to dissolve over time simply because of contact with gasoline. Mine, from what I can tell, isn't too awful bad in that regard, save for the cracks. But imagine...GM putting a bladder material in a fuel tank that dissolves in gasoline. Go figure.

Here's my plan, and hopefully anyone else in the same situation will find it helpful if the plan is solid. Step 1 will be to fill the cracks with Permatex fuel-impregnable gasket sealant. That'll fill any big gaps. This stuff is readily available at any auto parts store. Step 2, however, is the new tech out there, Red Kote:

http://www.dimecitycycles.com/red-ko...ler-liner.html

This may not have been available when the postings in the archives I found were written. But it looks really good, from what I can tell. I'll call the merchant and ask about possible use in a bladder-lined tank, but I suspect it'll work just fine. If anyone's interested, I'll post what the merchant says here in a couple of days and follow up with the repair results. If it works, it'll not only fill cracks and gaps but also solve the dissolving bladder issue.

Damn sight better than scrapping the car.

Plan seem solid? Surely seems worth the try.

Kenn-----


First of all, the integral bladder on 78-82 fuel tanks (and also used on 84-96 tanks) will not dissolve in gasoline. However, the bladder is an organic material and, over time, will be deteriorated by contact with an organic solvent (i.e. gasoline). If they had used a bladder material like Teflon, then it would be relatively "immortal", but that's not what was used. I believe the bladder is either polyethylene or polypropylene.

Second, the purpose of the bladder is primarily SAFETY-RELATED. Bladders were first used in Corvettes for the 1975 model year (although the 75-77 bladders were separate and not integral to the tank). I think the safety consequences of a fuel tank mounted in the area the Corvette vulnerable to a rear end collision was the primary instigating factor.

I do not think that repairing the bladder as you suggest in your tank is going to fully restore the safety provided by the bladder. However, it certainly cannot hurt, so if you wish, go ahead. For one thing, I don't think that any of the materials you mention are going to bond to the native bladder material. So, while it will more-or-less "insulate" the gasoline from contact with the steel shell of the tank (which isn't really much of a problem, anyway), it's not going to really restore the integrity of the bladder. But, as I say, it's not going to hurt anything, either.

[Kenn S.]

Re: '78 - '82 Fuel Tank Sealant

Doing some research on Red Kote, it mentions it doesn't stick to plastic tanks. Other brands work with fiberglass, but no mention of plastic.

Thanks, Joe. Upon reflection and based on your thoughts, I think I'll just stick it back on the car and not worry about it. It'll be no more dangerous than my '70, and screwing with the bladder if not a sure thing just invites troubles later (liner coming apart in the tank). There aren't any other leaks to deal with, so it should be fine.

Thought I had something.