Fixing a plastic tank

So I was flushing and cleaning out the cooling system, starting out by cleaning out the expansion vessel.



When getting rid of some gunk I see this creative fix of some previous leak.


The fix consisted of probably all silicone they found in the garage and some random piece of rubber.


It seemed to have worked but I think the good ol' Buick deserves a bit better. Starting by drilling the hole clean using a stepdrill. Then I cut out a plastic disc using a holesaw. The plastic comes from the lid of a lunch box that felt sturdy. I am clueless when it comes to welding plastics, I just took a chance with the material selection. The diameter was not perfect so had to grind it down a bit by putting it on a drilling machine and holding it towards a piece of sand paper (not shown in the picture).


Then I welded it using a soldering iron and a small heat gun. I had not done this before and honestly did not know what I was doing. So it probably both looks and is a bit of a hack. But at least it looks (and feels) better than before I think, and it is leakage free so far