pheller
pheller UltimaDork
3/5/20 9:53 a.m.

My recent Prius acquisition has lead me down the rabit hole of EGR problems. A common fix on Priui is to add an oil catch can. 

I know this is pretty common on a lot of other cars as well - but here's my question: is bigger better?

For example, if the EGR system piping (the barbs coming out of the block or intake) are 3/8" tubing, is there any advantage to using large tubing to the OCC? 

Or, are there any advantages to using the OEM sized tubing, but a larger catch can? I see OCC that's are clear and hold .5oz, and huge ones that hold 10oz. Aside from draining the smaller one more often, is there any advantage to the bigger one? 

79rex
79rex Reader
3/5/20 8:48 p.m.

A bigger catch could be emptied less?  Otherwise I'm not sure of an advantage.  Someone smarter then me may explain how a larger one affects pressure.  

GameboyRMH
GameboyRMH GRM+ Memberand MegaDork
3/5/20 11:29 p.m.

I can't think of any advantage to a larger catch can other than a longer maintenance interval. Larger tubing will only help if the volume of blowby gases is so large that the stock tubing size becomes enough of a restriction to cause crankcase pressure buildup. I wouldn't consider increasing the tubing size for a small-displacement stock engine.

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