what goes behind the cam shaft at the back of the head i have a oil leak at the back of the head and i think a oil cap is missing or fell out i dont know what to ask for at the parts store its some kind of circle gasket or plug thanks for the help

 

Should be a halfmoon and come with the V/C gasket. You can remove it and aplly RTV liberally if you can't find one.

 

you are on a mazda site. but we need info to help you out.
year/model/engine/drivetrain. all will help to know what your needs are.

these maybe???
should be in the valve cover gasket set.

 

its not half moon i think its circle like the gasket shown in this attached pic.

 

Print that pic to show them. It is probably called a cam plug.

 

ok guys so i got the gasket on the pic shown above but it looks kinda like a dust cap. but its medal inside and a rubber coat on outside. i dont know weather the cup part goes twards the cam or the back part twards the cam it seams like it would fit both ways