Fuel tank drain plug seal

[WikedPlymouth]

Good morning,

I just replaced the fuel tank in my 1958 Plymouth with a nice used one from John at Big M Auto. The tank cleaned up nicely and I replace the filler neck O-ring and the sending unit gasket. I didn't think about the drain plug gasket and now that I have fuel in the car I see it is starting to leak slightly. The drain plug did turn so I can remove it. My question, on other tanks I've pulled (including the original to this car) there does not appear to be any gasket or washer. What have people used here? Just a large cooper washer or is it a fiber gasket or do you coat the bolt threads with something? Thanks.

 

[WikedPlymouth]

Wow, over 50 views. I guess no one has ever had this problem.

 

[CBODY67]

Maybe put a good copper washer in there and get it brazed closed?

 

[Ross Wooldridge]

None of my fuel tanks have had a drain, so I'm not familiar with the issue.

 

[Jakter]

Maybe put a good copper washer in there and get it brazed closed?

I would not get it brazed closed.
I took a tank in from a 1957 Dodge Sierra told them to test for leaks and fix them.
Apparently the drain plug leaked, I had not put fuel in this tank to even know the plug leaked, when I got it back they brazed around the drain plug.
I was not happy knowing that I would have fixed the leaking plug as soon as I was aware of it but they did what I asked and fixed all the leaks.

 

[Jakter]

Is the head of the plug where it meets the tank concave on the side facing the tank?
I had a 1960 Chrysler New Yorker that I wanted to clean the tank and pressurize with air to pop out a large dent.
When I pulled the drain plug the concave area under the head had a hardened type of sealer that resembled dried putty, don't know if it was factory or not.
Anyway, I cleaned it off and put a strand of plumbers putty in the concave area, tightened it down and removed the excess putty that squeezed out.
I had the car for several more years and it never leaked.

I had also thought of using a gas resistant O-ring.

 

[volksworld]

if the drain plug has a head that seals against the tank, I'd look into a Stat-o-seal washer...if its a tapered pipe plug with no head I'd vote for teflon tape

 

[WikedPlymouth]

Thanks for the suggestions. I plan on draining the fuel today to see how the drain plug/surface looks. Luckily I only put 5 gallons of fuel into the tank.

 

[WikedPlymouth]

Got the tank drained and cleaned up the bottom of the tank. The threads looked good and I noticed the drain plug head has a curve inside indicating it had some kind of gasket in the past. I installed a large rubber washer and used Teflon tape on the threads. I reinstalled the drain plug and put some fuel in it. I waited about 10 minutes and did not see any leaking. Will check today to see if it's still good.

 

[Sixpactogo]

No help for you but My 60 Dart has a drain plug. I drained it once back in 1983 years ago when I restored the car. I do not remember what if any seal was there but it has not leaked or been a problem. Maybe yours was just loose. Here is a recent pic.

 

[Toolmanmike]

Got the tank drained and cleaned up the bottom of the tank. The threads looked good and I noticed the drain plug head has a curve inside indicating it had some kind of gasket in the past. I installed a large rubber washer and used Teflon tape on the threads. I reinstalled the drain plug and put some fuel in it. I waited about 10 minutes and did not see any leaking. Will check today to see if it's still good.

No help for you but My 60 Dart has a drain plug. I drained it once back in 1983 years ago when I restored the car. I do not remember what if any seal was there but it has not leaked or been a problem. Maybe yours was just loose. Here is a recent pic.

View attachment 732205

Thanks for the photo of the tank with the plug. At least we know what the outside looks like. @WikedPlymouth , we need a photo or two of the plug and where it seals against the tank to be able to help here.

 

[WikedPlymouth]

Thanks to everyone for the comments. I checked today (24 hours later) and there are no drips at all. Everything seems sealed. I have another tank that I pulled out to replace with this one. I will take a picture of the threads and bolt so that will help someone else in the future with this issue.

 

[WikedPlymouth]

Attached are pictures of the old tank drain plug and threads. These were exactly like the replacement tank I got from Big M Auto.

 

[Toolmanmike]

Attached are pictures of the old tank drain plug and threads. These were exactly like the replacement tank I got from Big M Auto.

View attachment 732230

View attachment 732231

The ridge around the edge does the sealing.

 

[WikedPlymouth]

Are you referring to the ridge around the outer edge of the drain plug? The old drain plug had a very crusty and dried gasket of some type that filled in the concave area under the drain plug head. It was where the rusty orange look is on the drain plug.