I am doing head gasket.

 

Does anyone know if I should redo the half moons that are on the back side (towards flywheel) of the head. If so what sealant should I use? Permatex Ultra grey okay. Subaru Service Manual doesn't mention it all all in Cyclinder Head service procedure.

yes, you should but you should put in new half moons, rather than trying to reseal those in. If you can't get them or don't want to do it, it is better to leave them alone, than take them out and reseal the oil ones. Grey High Temp Permatex will work.

 

Also put a dab of it where the camshaft seal housing and the valve cover gasket touch. (There should be little bit of it dried up there, so clean that off and then add somemore.

IIRC mine were in so tight that I couldn't easily get them out, so I left them alone. The sealant used at the factory seems really good. No leaks so far.

I do have new half moons...I will see if I can pull them out...if not I will leave them alone...

 

thanks

If they don't come out, put a little silicon over them before putting the valve cover back on.

I sprayed some permatex gasket remover and they pulled off real easy. Put in the new ones.

 

Does anyone know what function the half-moons serve? Why not just have metal there instead?

I think those are the result of line boring the heads for the cam journals.