Power Steering Reservoir Cap

Hi all,Rookie question here. Looking to see if anyone has encountered what I currently have. Running a KSE tandem pump. The instruction state to use a vented cap which is what I have been using. For the past few nights my car would smoke by the headers. Looked like I had a power steering fitting come loose. Nothing is strange, normal fluid level but after tracing it all, it appeared the fluid was coming from the power steering reservoir cap. Did a quick switch at the track from the filler tank to the power steering reservoir and like magic, my problem disappeared. The cap I switched it with was not vented. We assumed the cap o ring was bad so I ordered a new vented cap. I guess I’m am curious if the cap itself went bad or it’s pushing out fluid where the cap vents. Just curious if anyone else had some type of phantom leak while using a vented cap?Thanks!

Just had 2 weeks of steering problems. After 8 laps or so, steering got heavy. After 20..my arms tired. I threw on wrong cap somehow bc it looked newer. When I took cap off after race..it let out a lot of pressure. Fluid went blackish too. Changed fluid and ran custom vent line from top of cap down and testing seemed good. Thought it was servo but my good back up had same issue. Hope I didn't wreck seals in pump.....

How his is the fluid level. It should be below the return