Mercury spitting out water where it should not be

[spareparts]

inside of cowl, stb side? Thats the poppit valve letting you know it needs replacing

[soulseller]

How difficult is this to DIY? I'm pretty comfortable wrenching but I have limited marine engine experience. If its going to be a big project to get at it I'd rather give it to someone else to do, its too hot to keep her down for too long.