Surely someone out there has had to replace thier spark plug tube seals on a ES300 before. I have the same question about tube seal replacement that LEEVIV posted but haven't had any luck finding out how to change them out. Specifically I would like to know how the new ones go back in because it's not very difficult to remove the old brittle ones but they're worthless by the time you get them out.
If you look at how the old seals are in there, you need to take a punch or a flat head screwdriver, and bend 2 metal tabs back that are helping hold the seals in place. once you do that, then you can use the screwdriver to pop the old seals out. Be careful not to gouge the metal seat that they rest in. To put the new seals in, I used a big socket that was almost identical size to the seals, and then tapped them in by resting the socket on top of the seal. Once that is done, then take the punch and bend the metal tabs back over the seal. the end :)
Thank you jet_a_jockey for taking the time to explain the removal and replacement of the tube seals. When looking at them it doesn't seem as though you could bend them back but sure enough, it worked for me. :D
