Gas tank leak

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scrag

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Hey everyone,
Well my sons 68' dart recently leaked gasoline.......question is why? Well we looked for the source and found there are not holes and are no rust spots so no help there, but we found it was instead coming from the sending unit area. From what it seems the gasket either was not on good or not on in the right area (it was not centered but instead more upwards and the leak was where the lesser of the gasket was) or it wasnt on tight enough. So since he has pulled off the sending unit to check for holes there, and came up empty. This leads us to believe that the gasket location wasnt a sufficient seal and led to a leak. I've decided to make a bigger gasket myself hence we live in hawaii and no auto store carries the lock ring and gasket. My question is is there something im missing and what materials can i use to make a gasoline proof gasket? I was thinking quark. Opinions and some help would be awesome right about now. THANKS.
 
Ya mean cork? :-D Yeah, I`ve done it, but I smeared both sides in a good fuel resistant type sealant, edges also and let tack real good. Seems to be holding just fine.:clock:
 
I had a few leaks at the fuel senders on several Mopars. Usually because the lock ring wasn't tight enough. Rather than make a thicker gasket, try bending the 3 ears out more. Make sure everything is perfectly clean and no rust. Coat the gasket w/ kerosine or mineral spirits to help it slide. There is a special tool for installing the lock ring that isn't expensive (~$7?). I'll have to get it and stop using a screwdriver and hammer.

It is hard to install it correct with the tank on the car, especially since you should tap the lock ring evenly at all 3 ears to get it centered. Removing the tank is easy if you use up the gas first. That yields other benefits like fixing rust and blowing it out.
 
How can i center the gasket then because several times its seems to want to shift upwards. I'm not sure a thicker gasket but i'm kinda leaning towards a larger gasket in diameter. My gasket is a simple piece of rubber. no O- ring ...idk if thats what everyone else has but yupp.
 
The factory rubber gasket always worked best for me. The dealer should still stock it. Another area often overlooked on sender leaks is the steel fuel line that goes through the sender plate. The soldier connection there is prone to popping loose. Also, on A-bodies especially, many get pin hole rust on the upper surface under the trunk floor. You have to pull the tank to check that. Don't forget to reinstall the insulation pad. Usually you can see where the leak is as it will leave a fuel stain.
 
for an extra seal can i use a silicone sealant? such as RTV and if so which kind is better the RTV Black, Blue or grey? they all say gasket maker but i've used them with gaskets for a guaranteed seal. any ideas?
 
Bending the ears up is the thing to do. However, I recommend removing the tank to do it. I just got done with Bruce's ex's dart. I say remove it because, since the sender is located on the side of the tank, it's very easy for the gasket to slip out of place. With the tank removed, you can stand it on the back side with the sender hole straight up and get the gasked positioned correctly and see what you're doing. It's very easy to remove and install the tank. I wouldn't use any kinda sealant.
 
Thanks everyone for the advice and ideas, i will let you know the out come when i get there. I've decided to make a thicker gasket out of cork with no sealant and while the tank is in the car, the last time i took the tank out it wasnt so happy. I am also going to bend the 4 prongs on the lock ring a little more back. Is is supposed to be on top of the prong or in-between prong-bend and the bump?
 
I just dealt with this so I'll let you know what I did.

I ordered a lock ring and gasket from Jegs.

Went to install it and even though the gasket was the same thickness, it wasn't even tight when I'd turn the lockring.

I removed the gas tank and made myself a gasket "spacer" out of gasket material. I put that on top of the rubber gasket and in between the lock ring. Now it was tight and I tapped the lock ring all the way until it stopped. Hasn't leaked since.

Be sure to put some vaseline on the gasket in case it leaks again, you don't want it coming apart if you have to pull it back out. No need to use any kind of sealant becuase the gas will just eat it away. The tab should sit in between the bump and the prong. I personally wouldn't try cork but I'd like to hear how it works out.
 
One trick I have heard is to stack two rubber gaskets, but I would try bending the ears first. I agree w/ ESP47 that the lock ring tabs should sit in the slots on the tank ring. I know that tends to make the ring lose, so tempting to leave the ring at its tightest, but it could then vibrate lose.

As cudamark mentions, a younger brother had a Duster where the tank rusted thru on top after spilling water in the trunk. There is a recess in the tank under the large round plastic body plug in the spare tire well, a great place to hold water. That was in Florida where spills don't evaporate. He and Pa insisted on a $1 epoxy fix, though I advised getting another tank. Didn't work so my brother sold the car cheap ~1983. Nice looking car - yellow w/ black race stripe, though a slant six w/ 3-sp manual ('72 I recall).

I didn't bother replacing the factory blanket on top of the tank in my '65 Dart recently. Couldn't find it and vaguely recall discarding since degraded. I glued leftover trunk weather-stripping in a few bands as cushioning. It feels firm and quiet. I recalled my brother's experience and thought better to have air gaps so water can't sit on the tank. I also wire-brushed and painted the outside. The inside looked pristine. Hold it so sun shines in the filler hole and you can see well.
 
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