engine blowby
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engine blowby
I have a 1987 f250 with a 351w motor, I am getting oil blowing out the dipstick tube. there is no smoke coming out the exhaust and the engine runs smooth. The pvc is new and the lines are not kinked or restricted. Does anyone have any idea what might be causing this besides the rings.
Postmaster
Joined: Mar 2013
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From: Over There
The PCV "valve" is too restrictive, either gut it buy opening up the bottom and removing the internals. Or swap it out for just an elbow.
Also I put a free flowing PCV in both valve covers.
If that sounds extreme at least check the flow of the fresh air vent on the other side.
IMO you don't need a fresh air vent and in fact fresh air vents aren't a good idea but without adequate PCV you need it.
Also I put a free flowing PCV in both valve covers.
If that sounds extreme at least check the flow of the fresh air vent on the other side.
IMO you don't need a fresh air vent and in fact fresh air vents aren't a good idea but without adequate PCV you need it.
Postmaster
Joined: Mar 2013
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From: Over There
What vacuum? where? What are you talking about?
PVC is Polyvinyl Chloride a type of plastic often used in pipe.
PCV is Positive Crankcase Vacuum, a condition where the pressure in the crankcase is lower then atmospheric. If you had a functioning PCV system it would be impossible for the dipstick tube to blow out oil.
PVC is Polyvinyl Chloride a type of plastic often used in pipe.
PCV is Positive Crankcase Vacuum, a condition where the pressure in the crankcase is lower then atmospheric. If you had a functioning PCV system it would be impossible for the dipstick tube to blow out oil.
Laughing Gas
Joined: May 2009
Posts: 854
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From: Maine
Right...it's PCV. But, it is Positive Crankcase Ventilation.
It is possible to have a functioning PCV system which is just overloaded by too much blow-by. The OP was worried about his rings...and, rightly so.
Roy
It is possible to have a functioning PCV system which is just overloaded by too much blow-by. The OP was worried about his rings...and, rightly so.
Roy
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Postmaster
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From: Over There
Engines wear out, they have blow-by, the stock system is retarded and is barely adequate for a new well sealed engine, it must be changed.
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It's "ventilation". The key word here is "positive", not "ventilation". All crankcases are vented, they have to be. Even with the old Road Tube setup there was a breather vent to let the air in - usually steel wool was used in the oil-fill cap as a filter. The Road Tube created a vacuum as the car moved down the road. PCV just returns the gasses to the motor to be burned instead of dumping them out into the atmosphere. PCV was the very first Emission Control device.
Postmaster
Joined: Mar 2013
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From: Over There
It's "ventilation". The key word here is "positive", not "ventilation". All crankcases are vented, they have to be. Even with the old Road Tube setup there was a breather vent to let the air in - usually steel wool was used in the oil-fill cap as a filter. The Road Tube created a vacuum as the car moved down the road. PCV just returns the gasses to the motor to be burned instead of dumping them out into the atmosphere. PCV was the very first Emission Control device.
More Turbo
Joined: May 2014
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From: Lakeside, Arizona
You have a big vacuum leak somewhere. It will cause the oil to exit the dipstick, ask me how I know. 
Check the line from the airbox to the valve cover on the drivers side of the engine. It may be disconnected or broken. Look also at the brake booster vacuum line for the same.
Check the line from the airbox to the valve cover on the drivers side of the engine. It may be disconnected or broken. Look also at the brake booster vacuum line for the same.
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There is no vacuum leak, if there was the carb. would be running lean and the engine would be running rough, which they are not.
The vent side is clear with no restriction from the valve cover to the air cleaner.
The vent side is clear with no restriction from the valve cover to the air cleaner.