Seadoo jet boat oil tank

[Water sports]

Hi can anybody help me I am just wondering if this valve at the top of the hose off the tank should be allowing air in and out. I am trying to pressurise the tank to see if there are any leaks. This is a brandnew tank fabricated to match my existing plastic one

 

[boonie53]

That valve is to let air into the tank it is a one way check valve to check it remove it put a vacuum pump on it it should hold vacuum one way and not the other install it so the tank can get air in or it will form a vacuum in the tank and stop the oil flow to the pump causing engine failure from lack of oil