Top Of Gas Tank Leaking

[Dennis Detweiler]

This is the first time I filled the tank since I bought this 39 Plymouth. I'm getting it ready to store it for the Winter and thought I should fill the tank to prevent moisture and rust on the inside. When full it started flooding out from the top of the tank. I'm hoping it's just the sending unit gasket? Or, are these tanks known to rust out from the top side?

[bobostski]

The tank on my  49 Chrysler  rusted out on the top also. It had been stored for almost 30 years in an airplane hanger. I think moisture condensing in the tank rotted it  out.

[Los_Control]

Why is it always when you need to pull the tank, it is full?

[Dennis Detweiler]

The gas gauge doesn't work either. If the tank is rotten on top, the sending unit is probably kaput along with it. Just when I think I'm finished buying and replacing parts, I find something else is worn out. Well, the body and interior is nice. After I replace all of these parts it will be a new car again.  

[busycoupe]

When I first filled the tank in my car 10 yrs ago, I discovered that it had a crack on the upper rear corner.  I ran the car for a year or more by not filling the tank entirely.  Finally I pulled the tank and had a local  radiator shop clean it out and solder the crack.  It apparently cracked because someone had tightened the tank straps too much.  It has been OK since.

[Bryan]

Bought a replica fuel tank on ebay for about $300.

[desoto1939]

When storing your car for the winter get some Stabile 360 product. When mixed with your gas it created a vapor that will coat the top of the tank and any exposed metal to prevent rust becasue of the ethenol and water in the gas. It will last for 12 months and also helps clean the fuel lines and carb.

I use it regularly in my 39 desoto and I have the original gas tank. Can get the product at walmart.

Rich Hartung

desoto1939@aol.com

[Dennis Detweiler]

If I have to replace the tank, has anyone installed one of the new Poly tank replacements in their car? They are about $240.00. I wouldn't have to be concerned about the condensation rotting the tank.

Are any of the available new 5 bolt sending units compatible with the 39 fuel guage? 

I may get around to inspecting the tank for prognosis before Winter. Otherwise, it will be Spring before I get to it. 

[plymouthcranbrook]

On 11/2/2017 at 9:59 PM, Los_Control said:

Why is it always when you need to pull the tank, it is full?

At least most have drain plugs unlike modern plastic tanks

[50fordtruck]

I had a leak at the top of my 47 Ply. tank . I got it off and found that  someone but a long screw in the cover over the fuel sending unit and put a hole thru the tank.