I have been working to stop a slow drip leak from near my fuel sending unit, stock 76 280z.

When I fill the tank above about 3/4, I get a slow drip from that area.  It is hard to tell if it is the o ring or the elec. connectors, or maybe a hole in the top of the tank?

I have installed the new o ring, and also a new locking nut.  I also put some JB waterweld around the electrical connectors on the outside (I didn't want the chance of putting anything on the inside in case it fell off into the tank).

No leaks right now, since the tank is about 1/2 full.

Is there a special tool for these lock rings?  I used the screwdriver/hammer method.  There is a small tab on the locking ring that I cannot tighten further.  (How far am I supposed to turn the locking ring?)  I cannot tighten the ring any further, it started bending the tabs.

Here are the tabs I cannot tighten further.  Is it supposed to tighten to the arrowed tabs, or all the way the the sharp "stoppers"?

 

I just used my hand to tighten most of the way, and then some water pump pliers set wide open to get on the tangs for the last few degrees. I stopped at the tabs indicated. the hardest part was keeping the gasket in place. I used a little dab of fuel resistant gasket sealer to make sure it did not get displaced. no leaks so far.

Edited July 20, 20168 yr by Dave WM

It has been a while but I think you need to turn it until the high points go past the ramps so it cannot back out. Use a lever and grab it by the tabs across the ring to turn it smoothly rather that using impact.

40 minutes ago, beermanpete said:

It has been a while but I think you need to turn it until the high points go past the ramps so it cannot back out. Use a lever and grab it by the tabs across the ring to turn it smoothly rather that using impact.

oh now that makes since, I better go tighten mine a touch more then.

4 hours ago, beermanpete said:

It has been a while but I think you need to turn it until the high points go past the ramps so it cannot back out. Use a lever and grab it by the tabs across the ring to turn it smoothly rather that using impact.

I used a tire changing tool for dirt bikes, we always called them spoons, flat steel with the ends angled up for prying under the beads. Put one across the locking ring and turned it until it hit the notches pass the ramps.

Past the ramps!

Can't edit from my phone, don't understand that.

Thanks for the replies, I'll try to tighten it a little further.   The electrical connectors seem to be in the way if I try to use the lever across the ring method, but I will try it. 

My intuition told me what has been mentioned, that I should tighten it past the tabs, then the tabs keep it from backing out.

There is a youtube video of a guy fixing this leak on a 240z and he stopped at the tabs, so I thought I'd verify.  

Thanks for the feedback

14 hours ago, siteunseen said:

Past the ramps!

Can't edit from my phone, don't understand that.

Perhaps I am using the wrong terminology. The o-ring has to be held between the tank and the sender unit to seal. Either the lock ring or the tank has ramps (wedges) that the other half rides on to make the seal when you rotate the lock ring. As you tighten the ring those tabs (shown in Ramsesosirus's photo) go past the end of the ramps and fall into a depression which prevents the lock ring from rotating the other way.

I had the leak on my 1976 280Z. It turned out it was coming from the electrical connections on the sending unit. There are small O-rings under the riveted connections that dry out and crack.

I used JB Water Weld which is designed to seal Water, Oil, Gas, Diesel, Hydraulic Fluids and most chemicals. It is a two part epoxy and will cure under water. Regular JB Weld products will disintegrate with prolonged contact with Gasoline.

I removed the sending unit and wire brushed all an area around the electrical contacts on both the inside and outside of the sending unit housing. Then I applied a bead of the Epoxy around both sides of each contact. Seems to  be working. So far I've had this applied for two years and no further leaks. But I'm still on the look out for a NOS sending unit.

http://www.jbweld.com/products/waterweld-epoxy-putty

 

 

7 minutes ago, Chickenman said:

I had the leak on my 1976 280Z. It turned out it was coming from the electrical connections on the sending unit. There are small O-rings under the riveted connections that dry out and crack.

I used JB Water Weld which is designed to seal Water, Oil, Gas, Diesel, Hydraulic Fluids and most chemicals. It is a two part epoxy and will cure under water. Regular JB Weld products will disintegrate with prolonged contact with Gasoline.

I removed the sending unit and wire brushed all an area around the electrical contacts on both the inside and outside of the sending unit housing. Then I applied a bead of the Epoxy around both sides of each contact. Seems to  be working. So far I've had this applied for two years and no further leaks. But I'm still on the look out for a NOS sending unit.

http://www.jbweld.com/products/waterweld-epoxy-putty

 

 

Maybe I will apply the water weld to the inside as well.  My issue with it is it isn't like regular JB weld, it is more like a putty, therefore harder to get into all of the crevices.  If it was more of a liquid, it would be easier to seal it up. 

I had a leaky o-ring a couple years ago, so I replaced it from MSA and all was fine. Then, this year, the washer/rubber gasket around the (+) electrical connection started leaking like crazy, and I did try a repair with something like the JB Weld, but it's tricky as there isn't a lot of room on the inside of the sender. After some fiddling, I just ordered a new one from MSA, a new rubber o-ring (you have to get one that's fuel rated), and a lock ring. I think everything came to about $70. It took a few minutes to put in and no more leaks!

Here's the sender...the o-ring and ring come up as well. In truth, my o-ring and ring were probably just fine, but I hate mucking around with leaking gas, and I wanted it fixed. It is.

http://www.thezstore.com/page/TZS/PROD/11-3271

Edited July 26, 20168 yr by z boy mn

If it's leaking wih the electrical connections, better get a new sender, or replace it with a used one that doesn't leak. Yeah the lock ring is supposed to pass the notches. ( New sender comes with a new o-ring, or else like said above, get an o-ring that is fuel resistant