Smoke from rocker cover vent

[Mary Mac]

I noticed some smoke in the engine compartment today. I hadn’t run the engine in a few months. It’s coming out of the rocker cover vent. Is this normal? Is it blow-by? Engine oil level is good. Westerbeke 30 4-91

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[rcvesselstyn]

Hi Mary. Yes that's normal. A combination of blow by and hot vaporized oil. It'll leave a sticky residue in your engine compartment and make your boat smell like oil. Run a hose from the vent to a PCV valve available at any auto store. That's a positive crankcase ventilation valve. Continue the hose to your air intake you can either hang it in front of the intake or connect it to the base of your air cleaner like I did. Since unfortunately on occasion we run the engine for 5 or 6 hours (like when our rigging failed on this last Catalina trip).We have a sealed system so even when the engine gets good and hot our engine compartment doesn't smell like oil and everything isn't coated with a black sticky slime. Glad to hear you're back at the boat!

[Mary Mac]

Thanks, Randy. After replacing the exhaust elbow and hoses and getting rid of that leak, I guess it made this more obvious.
The air intake is right next to this and has a lot of oily soot. The vent points at a grate on that rectangular intake cover with the wing nuts. Can you share a pic of how you connected yours? I don’t think I have an air cleaner.. haven’t seen one!

[rcvesselstyn]

I have a Universal M18 so it wouldn't be helpful, but these pictures might help.

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this was the earlier configuration, with a brass pipe to the side of the air cleaner.

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This is similar to the disposable air cleaner.

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You have a intake silencer.

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The brass pipe went to just under the cover.

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This one was modified to direct the crankcase gases into the screen area.