This is the main thread: Oil Catch Can, Eliminate that knock! | PriusChat To clarify: there isn't an Oil Catch Can on the car from the factory, it's an aftermarket install, basically spliced in along the hose between the Positive Crankcase Ventilation valve (kinda buried, under intake manifold), and a spigot on the intake manifold, just downstream of the throttle body. It's a good idea to do OCC install in conjunction with intake manifold cleaning; that hose from the PCV valve to intake manifold is pretty much the main source of oil/gunk fouling in the intake manifold. So, clean the manifold, then install OCC. Watch @NutzAboutBolts video on intake manifold cleaning here: Nutz About Bolts Prius Maintenance Videos | PriusChat He hasn't done one on OCC install, yet...
I think that I read that the banging is caused by a buildup of oil in the intake manifold and is sucked into the engine. Liquids will not compress. Does the OCC prevent the oil from getting to the IM and thus prevents the banging? And, how does the redesigned IM prevent buildup of oil?
More likely water or water/coolant, long story. As far as I know, it doesn’t. It’s reputably to provide more equitable allocation of exhaust gas to the cylinders, and perhaps not very effective at that either I empty my oil catch cans (two Moroso 85474’s in series) in conjunction with oil changes, and having gone to once-a-year changes (roughly 4000~5000 kms), so this is a full year’s catch. First can is on the left, is mostly an oil/water purée, with layer of mainly water at the bottom. Second can is pretty much the inverse, thin layer of oil at top, the rest water. each is about 60 cc’s:
