VCCA Home Forums TECHNICAL - GENERAL Mechanical - Engine, Trans, etc Installing gas tank sending unit

I am getting ready to install my rebuilt gas tank sending unit back into my '39 coupe. Should I use a gasket sealing compound on the gasket that goes between the unit and tank? If so should both sides of the gasket be coated? Or is the gasket to be installed without any sealer?

This may or maynot apply but with my 52 the original gasket was cork and thick. The replacement gasket that came with my new sending unit was a rubber like material and quite thin. Leaked like a sieve, and had to use two gaskets to solve the problem. One thing that bothered me was the method of shipping used. The two gaskets could have been sent in one envelope first class. Not the way they came, they were in a large nearly 8.5by 11 envelope with bubble pack and the shipping cost far exceded the cost of the two gaskets.

Y'all be cautious some sealants will not hold up with alcohol in gasoline. Many of the Permatex sealants contain alcohol in the formulation and are not compatible. Silicone sealants can also deteriorate with alcohol. If in doubt check with the manufacturer before relying on one of the old traditional sealants. That goes for some gasket material as well.

Hey glovell39,

My experience for what its worth.........

Two years ago I replaced the sender unit and gas tank in my 48 Fleetline. The original sender unit gasket was some sort of rubber material that turned to black mush......my belief is that the ethanol gas did it.....no proof, just my gut feeling. Anyway when I replaced the sender unit and tank I made my own cork gasket (about 1/16" thick) and installed it with no sealant. No leaks. And that, my friend, is my story and I'm sticking to it.

May you have good luck however you make the installation.

Thanks Ken,
I think I'm going to take your advice. One of my old buddies who is a retired Chevy mechanic told me the same thing. Cork gasket & no sealant.
Thanks a bunch. Gary L. - Marion, Ohio

I learnt the hard way 35 years ago not to use silicone sealers where petrol is concerned though diesel is not a problem.
I think cork only may have been the original sealer used but Gene or Chipper may have more accurate information.
Tony

Silicone sealants don't last with gasoline. They swell up and turn mushy. There are some sealants that can be used with gasoline. Permatex has one called "Permashield". Just got that information from Permatex. Expensive but they claim it works. I haven't tried it yet but have some on order at the local PH.

I completed installing the original tank sending unit in my '39 Chevy. I had installed an aftermarket unit a couple of years ago that was not working properly. I found that the aftermarket unit may have been malfunctioning due to not having a good ground. When grounded it was fine. This may have been because I used sealant on the gasket and it did not allow the screws to make a good ground connection with the tank??? This time I did not use sealant other than a little "seal-all" to hold it in place to align the screw holes, and I think it I going to be fine. A lesson learned. Now I have a spare. Thanks to all who responded to my post. GLovell39