The International Cessna^® 170 Association

c170b53 wrote:You’re going to find out its a ton of work. From memory, as I understand it there’s really only one gasket that’s sealing water from entering the tank, that’s the one inside the tank. The two cork gaskets are there to provide fretting / dissimilar metal protection. One, between the tank wing access panel and the fuel tank well. Second, between the fuel tank top and fuel well bottom mating surface. I thought Jim Wildharber had made a good presentation of the process of replacing these gaskets. It’s hidden here somewhere.
Success here will be measured by how easily the screws come out of the wing panel fuel tank access panel, a direct function of when they were last removed and more importantly how the screws come out of the filler neck adapter.
Really take you time, use mouse milk like its free, and here’s hoping good success.

Thanks for this. I'm going to put mouse milk on it for about a week beforehand to loosen up the screws. Making new cork gaskets and installing those too from the provided stencils.

I just want to add a cautionary comment with regard to manufacturing one’s own cork gaskets. I tried this about 15 years ago for gascolator gaskets to seal the glass cylinder top/bottom. My old Aeronca chief used cork gaskets on it’s gascolator so I was comfortable making them for the 170. About 4 months later I noticed fuel-stains along the bottom of the gascolator so I checked and re-tightened the lower cap (compressing thy cylinder a bit more) and used aerosol solvent to remove the fuel-stain.
About a month afterwards my annual inspection came due and the gascolator was disassembled to clean it (per the 100-hr checklist) and the cork gasket was completely disintegrated. I believe that gasket was about to completely disappear of it’s own accord and would have failed IN-FLIGHT with disastrous results.
My point in this post is to pass along the possibility that some sources of cork gasket material may not be “airworthy” and to be cautious in using it. Select quality material and use it only where Cessna did. The fuel filler neck area is unlikely to cause the problems in-flight the gascolator might... but, YMMV.

Watch the clocking of the filler neck. It has six screws, and the adapter/mounting flange has eight, and you want the cap handle to align with the airflow when it’s on and tight.