Leaking fuel gauge sending unit

[48bill]

I have a plastic "TANKs" brand fuel tank in my 48 Chevrolet convertible.  For some reason no matter what I've tried a leak developes around the sending unit.  I wonder and have had a few folks tell me it is the different rates of expansion between the plastic tank and metal sending unit flange.

Any suggestions on how to stop this other than keeping less than 1/2 a tank of gas in the tank?

[BFS57]

I have a plastic "TANKs" brand fuel tank in my 48 Chevrolet convertible.  For some reason no matter what I've tried a leak developes around the sending unit.  I wonder and have had a few folks tell me it is the different rates of expansion between the plastic tank and metal sending unit flange.

Any suggestions on how to stop this other than keeping less than 1/2 a tank of gas in the tank?

Hello;
Ive had this problem on my 57 Chevy. I have tried all kinds of things! Different gaskets, adding copper washers to the attaching screws, but have not tried some kind of sealant!
I don't know what you like but I do know that JB Weld works on a gas tank, I had an old jalopy that had a leaking tank so I jacked it up, wire brushed the places where it was leaking, applied slow set JB and let it cure over nite and NO LEAKS!!!

Bruce

[Bruce Dorsi]

Hylomar Universal Blue is a non-hardening sealer rated for use with gasoline.

I have used it for diesel fuel with good results.

[wayne petty]

hylomar is what i use also..

sometimes its hard to find. but Permatex 85420 is the same product.. and available at almost every parts store..

so you know what the package looks like


https://www.permatex.com/products/gasketing/gasket-sealants/permatex-permashield-fuel-resistant-gasket-dressing-flange-sealant/


edit..

i would also worry about how tight the flange is tightened down..   you may end up copying the flange bolt pattern on a piece of copper or even stainless sheet..  so you can put a split ring down thru the hole at an angle and have studs or just threaded holes.. so you are pulling flat on both sides of the plastic..

[enjenjo]

I do what Wayne suggests with the split ring. I usually make it from 1/8" aluminum, drilling ans tapping the holes for 10 x 32 screws. I install the screws into the ring from the bottom, and tighten the heads against the ring. A bit of Locktite doesn't hurt.  I then install the ring on the inside of the tank, and hold it in place with a couple 1/8" countersunk Pop rivets. Then you can install the sender with just one hand rather than needing three to juggle all the parts.

[UGLY OLDS]

That's a NEAT idea  :!:  :!:   ^^^^^^^^^^^^^^^^^^^^^^^

Bob...

[48bill]

I do what Wayne suggests with the split ring. I usually make it from 1/8" aluminum, drilling ans tapping the holes for 10 x 32 screws. I install the screws into the ring from the bottom, and tighten the heads against the ring. A bit of Locktite doesn't hurt.  I then install the ring on the inside of the tank, and hold it in place with a couple 1/8" countersunk Pop rivets. Then you can install the sender with just one hand rather than needing three to juggle all the parts.

I appreciate the replies.  I'm in a quandry.  I called the PERMATEX tech line last week before I put the request on the RRT.  They just called a few minutes ago and said that making a gasket of VITON rubber sheet and using the HIGH TACK GASKET SEALER with it would be better than using their PERMAFLUID FUEL RESISTANT GASKET DRESSING & FLANGE SEALANT which as Wayne pointed out is the same as "Hylomar Universal Blue Gasket Sealer".  He said both would work but the HIGH TACK GASKET SEALER would be better as there were no voids to fill which would be the best use for the PERMAFLUID FUEL RESISTANT GASKET DRESSING & FLANGE SEALANT.

I guess you can see my quandry.

Any thoughts on the PERMATEX Tech's suggestion?

[kb426]

I have no exp. with the plastic tanks so take this as a grain of salt. All the metal tanks came with a cork gasket and specified to use only the old Indian head sealant. I have good results using that but if you have rubber instead of cork, this is of no use to you.