Just finished installing a new gas tank in my Skyliner and what an adventure it's been. The biggest hassle has been installing the new sender unit. That piece came with a lock ring and an o-ring that plainly is too thick for the application (1/4 inch thick). There is just no way to compress that o-ring enough to lock it into place. When I looked at the original tanks o-ring, it was rounded on the bottom to fit into the groove, but the upper part was flat and much thinner than the replacement. I ended up trimming about 1/3 of the rings thickness off by mounting it on top of the lock ring and using that as a jig. Then by using a razor knife and heating it with a torch, it cut through the rubber like butter. The trimmed ring still had to be compressed a little, but I was able to lock it into place. Of course, the acid test will be when I fill it with gas. Anybody have a similar experience with this?
Similar, but different, lol. I can't remember (old age bad memory) exactly what the issue was, but after finding and ordering a quality fuel sender to match the ohms range of my gage, I found out it had the wrong type of mounting plate....maybe a screw-down?? I ended up morphing the new gage's inards onto the old sending unit's mounting plate, which fortunatly was still in good shape.
I tried to use a new sending unit from a sedan on my Ranchero by bending the arm. No luck. I ended up having a company called John Wolf (Pennsylvania?) rebuild my original stock sending unit ($135) and they included a new O ring. Worked great. John Wolf advertises in Hemmings. The price may have gone up as this was 3 years ago.
All of the original ford gas tanks that I have worked on had a square profile O-ring. The tank side has a curved seating area which would cause the O-ring to deform into a curved shape on that side. I would think you could use a normal round shaped O-ring in the appropriate thickness. Originally they were hard to get started during replacement, but the density of the rubber ring did conform. A 1/4" high does sound a little thick.
I wasn't too happy about the original designed rubber band type and tried to find a regular O ring to fit but never found one of the right diameter and thickness. After a few tries I finally got the original one to seal, it leaked the first few times.
Guess this is giving me a heads up on what to expect when my new tank arrives this week. How about a good grade of gas resistant sealer applied to the o-ring seal when putting it together?
I did apply a bead of gas resistant sealer with the altered o-ring - hope that helps. I'm not sure how that sealer reacts with rubber, but I figured it should add a little insurance. I originally tried to source another, better fitting o-ring, but just try to find the right one. In the universe of o-rings, trying to find one with the correct dimensions and not being forced to buy a case of the things is nearly impossible. You'd think that job should be the responsiblity of the vendors offering a part with the "correct fit".
One other thing I wanted to mention is that even though the tank is listed as a "exact reproduction" of the original, it is not. The shape of the original is square in the lower rear part of the tank. In the replacement it is slanted at a 45 degree angle. This does not affect its fitment in the car, but requires new, compatible straps to mount it and probably changes its capacity.
i had the same problem with the new sender i ordered. o ring was way too thick. ended up splitting it to be able to get retainer on. have not tested it yet, but hoping for no leaks.
My new tank arrived today and it had a rather thin cork gasket for the retainer. I don't plan on putting the tank in yet,as I need new straps and the right timing to do the job. Also ordered new strap bolts which came today. When I do the job, I will report back and tell how it went with that cork type gasket o-ring. Seems as though some type of permatex could be used on it. Will see.
Found this sealer that should work on my gasket and rubber o-rings that are used on any ones tank sender retainer.
Permatex? PermaShield? Fuel Resistant Gasket Dressing & Flange Sealant
Do a trial fit, one of the cheap replacement sending units I tried came with a flat thin cork gasket and when I installed the lock ring the sending unit was loose, no way it could provide a seal.