For sure not running a valve can be detrimental. Something for you to check on. Some of the later than 2000's, 4.0 Jeeps and some others didn't use a valve but had a metered orifice in the hardline going into the throttle body or manifold. Think of a carb jet in the line. Called it the CCV system if I remember correctly. You need something along that line to extract the gasses that collect in the crankcase and run them through. Keeps the engine clean on the inside, keeps oil cleaner etc.