I recently purchased a knightsports AST from Japan, and noticed there is no pressure cap, the unit is an aluminum drum with 2 hose inlet/outlets. What is the function of the pressure cap and is it a bad thing that it does not include one? I cant see one of the leading aftermarket rotary companies making a product that doesn't work effectively, any advice?

 

They must assume you already have a cap. It functions to maintain a specific pressure in your cooling system to affect the boiling point. Higher pressure raises the boiling point. If your system exceeds the pressure rated by the cap, it bleeds off coolant to the overflow tank. You need a pressure cap if your running water/glycol. If your running any zero pressure fluid (i.e. Evans), you dont need a pressure cap, but a cap none the less

 

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no cap in the pic....

 

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As you can see there is no cap, its just the aluminum drum, is this a problem, will the performance of the AST be affected in any way??

 

That ain't an AST. I would send it back, or eat it and buy one local.

 

It says knightsports right on it, what else would it be?

 

Found out they accidently shipped me a KSP oil catch can instead, thanks for the help and input everyone