I just pulled the valve cover today to adjust the valves and fix an oil leak up front. When I was putting everything back together I went to put the half moons in their place. This is the first time I’ve pulled the valve cover but I was expecting this to go pretty smoothly. Expect the half moon up front straight up wouldn’t fit. The rounded section was WAY too small. They would fit in the rear one but wouldn’t go more than half way down in the front. I don’t know if the previous owner put some jank Chinese head on here or what but I’ve never seen anything like that? Does anyone have any ideas or experience with this?

 

Get your measuring tools out and post some dimensions of the seals and head orifice?

 

when i did the valve cover for the first time on my 20r the half moons were way harder to get in than when i did my other truck (22re). i used genuine toyota parts. i just pushed them in and tightened it down, ive not had any leaks. i havnt seen any differences in the half moons sizes before so i thought it was strange too.

 

I assume you are installing new 1/2 moons.
The part number on oem 1/2 moons should be molded in. I'd check both old and new to see if that offers any insight. the part number should be 11183-38010.