Leaky Fuel Sender Gasket Investigation ('72 Satellite)

[Dibbons]

Recently replaced (for the second time now) the float inside the fuel tank that controls the dash fuel gauge (brass but full of fuel). It had not been leaking externally.

After reading all the rumors about how the retaining rings being sold are too thin, I purchased a new retaining ring and gasket (don't remember the source at the moment). The new replacement ring was thicker than the installed ring (.076" vs .049") so I felt good about that. Don't remember if I compared the gaskets (removed was .072" and installed .057"). That means the new combination had a thicker ring and a thinner gasket and together the total thickness of the new was .012" thicker overall. (.133" - .121" = .012").

Using my special tool to remove and install the locking ring, I found it difficult to tighten the new one but I did my best. I did use soap on the gasket to help getting it to turn. Filling up the tank, a customer standing near my vehicle starting yelling. I looked down and found the sender area leaking gasoline on the ground. We pushed the vehicle away from the pumps and two other customers helped me siphon a few gallons out of the tank (I gave them the "free" gas). One of them followed me home (about a five minute drive) in case something else happened on the way but arrived safely and thanked him.

The following day, I noticed the lock ring still had a smidgen left to turn before it bumped into the "stops". So I tried to tighten the locking ring some more with the tool, but would not budge. Ending using a screwdriver and hammer and got it to turn a little more. Filled up the tank, little by little, over several days only to find still leaking.

Today, removed the sending unit pickup and found the rubber gasket shredded to pieces. I did some measuring and found I have two new gaskets that match the thickness of the one I removed originally that measured .072". So I need to use that one and I don't see a problem in doing so. With respect to the locking ring, definitely not going to use the "leaky" one that measures .076". I have the choice between the one i removed originally .049", a new one I found the same size .049", or another new one in a small package with a gasket that measures .059".

At the moment, I'm thinking about using the old "original" ring that measures .049" (which may have been factory or may have been reproduction, it was installed more than ten years ago). My other options are a new ring with the same .049" thickness, or the other new ring with .059" thickness.

What I did not mention is that the thicker leaking ring is constructed so that in order to tighten it all the way, it needs to be spun more than the other rings (maybe about 1/4 inch). Perhaps one can see the difference in construction in the photo with the small red handle screw driver comparing two rings and the previous photo (photos #4 and #5). In photo #5, the leaking ring is on the bottom and the previously installed ring is on top.

 

[Cranky]

And it's still leaking??

 

[furyus]

I would use the original lock ring, and grease on both sides of the rubber seal.

 

[Dibbons]

Update: I first tried usiing the lock ring that had been installed the last ten years or so (.049"). Went on easily using special tool after coating gasket with creamy hand soap, maybe too easy. I then tried the new lock ring which was a little thicker which felt better (.059") In both cases, although I tried to encourage the lock ring to center itself, one of the three tabs looks to be just barely underneath its little catch (the one nearest the fuel outlet tube). Or maybe I'm not interpreting the position of the tabs and locks correctly.

If the lock ring is not situated correctly, I could try: a) taking it off and on again; b) tapping it as installed and to try to center it more; c) or leave it alone and hope it doesn't slip out some day.

For now, i' going to leave it alone, fill the tank up some, and find if it leaks any.

P.S. Looking at the photos, the lock ring may need just a little more rotation to seat fully. It's difficult to tell when it is at the end of its spin with all the waves and bump built into the three tabs. That's way I was tempted to remove the fuel tank altogether and install the lock ring on the ground where I would have a better chance to get it secured once and for all.

 

[Bird 426]

I got tired of messing around with your problem, because I had it too. I see that you are in Mexico. I used an aviation fuel tank sealant, it's called Pro Seal, there may be other names. It's a 2-part, 1 qt can and then the catalyst, a small jar. Aircraft Spruce in California carries it. Use the lock ring and gasket that go in and lock comfortably. Sealant on both sides of the gasket, install. You shouldn't have to get crazy with the sealant. My guess is that the flange of the gas tank is buckled, you should be able to see it. Then judge how much sealant to use. After curing, it can be taken back apart with a little heat from a heat gun. Otherwise, you can keep playing musical chairs with the lock ring and gasket. I have done this with two of my cars.

 

[Dibbons]

Update: I filled the fuel tank little by little over a period of days. It is now full and no signs of leakage.