cfair

I picked up a fairly rare gas tank for my 66 98 yesterday at Turner’s Salvage in Fresno CA for $200.00. It has a few issues that will need to be addressed.

I’m hoping some of you know more about gas tank repair than me. And tank refurbishment.


The filler neck has a leak and I know my mechanics can repair this with a support brace inside and soldering/welding. They’ve done this fix to my other tank(s?). The long neck on these tanks can develop leaks after 55 years of having gas pump nozzles shoved in. Auto-fuel shutoffs may have made this problem more frequent.

The main body of the replacement tank has a medium sized dent, but not a hole, on the bottom passenger side just to the right of the filler neck. The lower corner line of the tank got pushed in somehow, but seemingly not by a forklift, which usually pierce or really mangle the tanks I’ve seen. This one is “not obviously bad” by my read. But I’m no pro.

The yard guys thought the tank could “blown out”, which I think means to pressure re-inflate and rebend the tank as though it were a balloon. Are any of you familiar with this? Is it a radiator shop kind of thing? Or is this a tank-specialist kind of process?

I’m under no illusions that the tank has to be visually perfect, but I need it to be safe.

Do any of you have additional advice about how to prepare or redo this tank so it can live a long and safe life under my ‘66 98?

Looking forward to your comments, tanks in advance
Chris

OLDSter Ralph

Without pics, its guesswork. I would suggest you search for a "Gas Tank Re-nu" (franchise) place near you. I can't vouch for individual shops,but thats all they do is gas tanks. Good luck.

matt69olds

Any possibility of pushing out the dent from the sending unit hole?

if you plug all the holes, vents and seal the fuel cap, a LITTLE compressed air might pop out the dent. Id partially fill the tank with water, partly to help seal small leaks, and mainly limit the amount of air needed to fill. Use a bunch of hose to put as much distance between you and the tank. If you have ever seen the damage caused by a air tank splitting, it ain’t pretty!!!

Use a regulator to keep the air pressure low. If 5-10psi won’t pop out the dent, you need to come up with a better solution. While 10 psi doesn’t sound like much, multiply the air pressure by the total cubic inches in the tank, it quickly adds up to a sizable amount of energy.

Definitely discuss this with whoever solders the filler neck. Someone who repairs fuel tanks might have a better solution. And I would suggest having them test for leaks after the dent repair, I wouldn’t be surprised if pressurizing the tank creates new leaks. Better to find them before installing it.

cfair

I'm definitely leaving this work to the professionals. Your thoughts about water to reduce air volume are sensible as is the safety warning.

For better or worse, the dent is not too far from the filler neck.

If the neck comes off as part of the neck-leak repair, I think they could reach the dent with body working tools.

Koda

They may pop a stud on there and pull, like in body work.

bccan

Koda

In case anyone cares, apparently AATASH! means "Fire!" in Persian, which is what the guy yelled before it happened.

cfair

I enlisted my daughter as photographer and wanted to share some pictures for anyone who goes through 65-66 gas tanks after me. Maybe this post will take some of the mystery out of these forgotten tanks & allow some of you to make good decisions after me.

First up is a disclaimer: I got this tank from a boneyard. It has numbers that the guys there said were not from their yard. This means the photos below may not actually be a 65-66 98 Olds. But the tank fits the 65 4 door 98. I saw it mounted on the car. This means that everything below may be wrong, but I can confirm that the tank fit well in a 65 4 door Olds 98. Hollander reports that 65-66 98 tanks are the same. I'm out on a limb here, but not uncomfortable. The car I'd like to install this on is a 66 98 convertible.

Next, here are the dimensions of the tank, best as I can describe them. The walls are canted a bit so nothing here is really precise, but I'd call them ball park decent in case you're swapping something in from Buick, Caddy, Pontiac or others.

A tank which fits a 65 Olds 98. Doesn't look to be original to the car, but it fits.

So let's get in to the nitty gritty. Tank dimensions & filler neck length. These are the things that can foul us up if we get them wrong.

In my mind fuel tanks need to be safe & fit properly. If not, they're more or less a bomb under your trunk with no fuse. I have no interest in taking a chance on driving an incidiery device.

With the 65-66 88's/98's (+ maybe later) Olds used a 25 gallon tank. So you could get 250-350 miles out of a tank with your 425. The basic dimensions of the tank are a matter of physics as seen above. Since Hollander says not a whole lot interchanges, I'm guessing that Olds mainly varied the filler necks lengths in the mid-60's between the 88's/Starfires and the 98's since the bumpers and frames among the models were different. So, next up is are photos of the filler neck, which can be repaired, modified and so on, if the overall dimensions of the actual 25 gallon tank are close.

65-66 Olds 98 filler neck length. I think, but cannot confirm since the tank came from a boneyard. A lot of stuff can change in 55 years...

My daughter got a good close up of the length with my measuring tape bent over the neck kink to show a close up of the actual neck length:

65-66 Olds 98 filler neck length. These sometimes leak and can be repaired.

Tank Length, Width & Depth
65-66 Olds 98 Gas Tank Length

65-66 Olds 98 Fuel Tank Overall Length front to back. Or fore / aft if you're nautical..

Close up of the tank length:

65-66 Olds 98 Fuel tank just around 36.5" long front to back. The sides of the tank are canted making measurements a little inaccurate.

Here are the 65-66 Olds 98 fuel tank width shots:

65-66 Olds 98 Fuel Tank width. This is a 25 gallon tank, not to be confused with the smaller 442/Cutlass tank.

65-66 Olds 98 Fuel Tank width close up

Just about 30" wide. 2 straps hold it in, so if you're swapping in something different, the frame rails are one width limitation. If you're replacing, put some foam or sound deadening material between the tank and under-trunk floor to keep things quiet.

65-66 Olds 98 Fuel Tank depth
Since the tank is not exactly square or straight, please consider this an estimate. I suspect a lot of GM tanks might swap if they're the right 25 gallon capacity. But frankly even if you used a 24 gallon Chevy reproduction and it bolted up, your gas gauge would read about right.

Across the varying depth of the tank, it looks it's more or less 7" deep

Vent Line Variance
Well, this is interesting. My on-car tank has 2 vent lines at the passenger side front corner, the replacement tank has just one Hmmm. Not sure which is correct, better for the environment, better for fueling or within design spec. Suggestions?

Here's my on car tank:

Large and small vent lines on the passenger front corner of my '66 Olds 98 fuel tank. Both lines vent to the atmosphere, which is good for 1966, but I'm sure the EPA would have some words for me these days.

Here's the fuel vent on the tank from the boneyard. It's a big vent >3/8". Was surprised to see it's different from mine.

Single, large vent pipe (>3/8") on 65-66 98 Olds fuel tank. Why aren't there 2 pipes like my factory tank?

So, next up, just to document it, is the fuel sending unit from a '65-66 Olds 98. Or at least one that fit well enough to work for a while on the boneyard car.

Things to note here are
A) Output hose of 5/16" to the fuel line is bigger than the 1/4" return line;
B) Only A/C cars had a return line, heater-only cars were simpler (cheaper for GM...).

will be reusing my good NOS sending unit, so this sending unit will probably go into storage in case I need it later.

65-66 Big Olds (88/Starfire/98) fuel sending unit. Note that the sending unit is on the front of the tank, not on top.

Here's the dent in the tank I'm hoping can be repaired. Next week will be interesting to see what can/can't be fixed. This dent is on the passenger side, at the rear of the tank, so theoretically it can be banged out if the filler neck come off. Since the neck is leaking, maybe dent & neck can be fixed in 1 go. I'm crossing my fingers, or o.k., we repair my on-car tank.

Didn't scare me too much, but here's the boneyard tank dent:

Can this crease be "blown out" or knocked back into to position with body panel tools? Please let me know your views...

My $200 tank-purchase bet is that either this tank can be repaired to a good state, or it tells us that the on car tank is the best option to repair. Sad we can't get new, but those of you following along know that.

Hoping the photos and dimensions help some of you along the way.

cheers
cf

Greg Rogers

Thanks for all the pics. I find this interesting. Unless the dent is worse than it looks in pic, why not just leave it, if it doesn't leak there.? Not too noticable, is it? Keep us posted.

joe_padavano

Smooth dents can be inflated out (I've actually done this inadvertently while trying to empty a tank with air pressure). The problem is that the sharp crease in the dent in your tank will not be easy to straighten. By the time you get enough pressure in the tank to push that out, you'll already have ballooned the flatter portions of the tank out of shape.

The only way to get that dent out is to have the tank boiled out to remove all fumes and then to use a stud welder to pull it out. Or, live with it.

Tedd Thompson

My guess is that a paint less dent remover guy could pop that out without much trouble at all no heat involved. They have all kinds of long skinny tools to get into difficult places.

As youth I worked in an old world blacksmith shop and we installed trailer hitches on everything that rolled and repaired many gas tanks on farmer trucks tractors and pickups. A gas tank can be made inert by simply washing with a strong solution of dish soap and water then filled with fresh water leaving only the to be repaired area in a small air bubble. Eather spot weld a stud or heat up and pull that dent out shouldn't be a problem which ever way you go.....Tedd

Koda

That's not a dent, that's a crease. Like Joe said, the metal is deformed and worked, so it's stronger than the rest there, and will need pulled or lived with.

cfair

Gents,
Thanks for your advice. Great thoughts all. I can definitely live with the crease aesthetically.

I just wasn’t sure if it would create a weakness in the integrity of the tank which might threaten safety.

The tank will need to be boiled out just to clean up the turpentine and old junk in there now. And I believe to repair the crack at the filler neck. I really don’t want unknown age gas remnants and whatever dirt might be in there running up into my engine and potentially clogging my fuel line.

I know the tank is not dry. Meaning it didn’t leak out in the boneyard from rust or a hole. On the 3.5 hour return trip from the junk yard I had to run with the windows down to avoid the gas remnant fumes. So at least it’s got that much tank integrity. But boneyard dust got everywhere.

I’ll let you know where this lands. Many thanks again.

Cheers
cf