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73-87 Chevy _ GMC Trucks => Engine/Drivetrain => Topic started by: Joe-NC on June 19, 2012, 02:20:22 pm
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My valves are blowing oil through the breather hose into the air filter. I'm not going to get it fixed because the entire engine will need replacing soon, and I can't afford to keep spending money on it until then.
My questions:
Does that air from the crank going into the carb really help with gas mileage, or should I just do away with the hose?
Are there any caps that are really good at keeping the oil from going through the hose?
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Are you valve covers original? Do you know if they have the baffles in them? Should be a piece of sheet metal just under the hole in the valve cover to keep oil from splashing up.
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If it's getting all the way up into the air cleaner, then crankcase pressure is overwhelming the PCV system, and it's probably due to excessive piston ring blow-by.
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I don't see any sheet metal under the hole in the valve cover, so I don't know if there are any baffles. This is a 305, but don't know if the covers are original. The PCV valve is on the drivers side and goes to the carb. The hose blowing the oil is on the passengers side and goes to the air filter housing. As far as I can tell its just a 1" hose going directly from the valve cover to the air filter with nothing to block it at all.
As far as blow-by, yes it smokes a little when its cold, but not too bad at all when its warm. Maybe valve stem seals or piston rings, I don't know.
But would I be better to keep the crankcase air going to the air filter as long as I can find a way to block the oil ...or should I just let it vent to the outside air?
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its your valves and/or rings. I have the same issue with my 305. The breather doesn't need to go to the air cleaner for any reason. was just a location where the crankcase could drawn in cool air. If your looking at rebuilding or swapping engine do like i did, get a cheap aftermarket breather that is straight up instead of curved into the air housing. The oil most likely gets caught up there because that bend gives it a place to sit. With a vertical breather the splash will drain back into the valve covers.
But like i said this is a cheap temporary hold till you fix or replace the issue. Im swapping to a 350 soon and just didnt feel like changing the breather filter a hundred times.
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Use a push in breather in your valve cover (that may be what usar17 is talking about). If you haven't changed your pcv valve it wouldn't be a bad idea, however you probably have serious issues. I've seen engines run a long time with this condition though.