Oil from breather?

[EdwardK]

Just got back from the salvage and scrap yards, (Crazy mad hills there and back.) my carb sticks on occasion and it decided to do it again coming up my drive way. I pulled the top off the air box to find oil in it. Not like a puddle or spewed all over the place, but obviously fresh oil that wasn't there last time I had to mess with the carb.

 

Truck is running fine, and not giving me any problems, just a little worried... Think the hills had anything to do with this? I had to engine brake going downhill and the truck doesn't have enough power to get outta second going up the hill to the salvage. (My F-150 has to go up that hill in first.)

 

The point I'm getting at is; I was going up and down crazy steep inclines, could oil have maybe just sloshed up in there? Or do I have bigger problems on my hands?

[metalmonkey47]

Probably just blowby picked up oil. If you were driving it hard, this will be more evident. 

 

I'm guessing you haven't done a compression test in a while? Might be time to do a wet/dry test and see how it looks. Rings are probably pretty worn. 

[datzenmike]

No.

 

If you were running high RPMs and full throttle this is just excess blow by, combustion gasses forced past the rings into the crankcase. They have to go some where and the easiest way out is the valve cover vent hose that is connected to the air filter housing. Now when the motor is well revved up a lot of oil is being sprayed around from the rod and main bearings. If extremely steep, oil can puddle into the front of the oil pan and be whipped into spray by the spinning crankshaft. All this produces a fog of oil droplets that can easily find their way up under the valve cover. On the top underside of the valve cover is a screen to help filter out oil spray and let it drip back onto the head, but if over burdened with too much oil spray and/or too much blow by it will work it's way past these baffles. The blow by will push this oil fog out the valve cover vent and into the air filter where it will puddle.

 

I guess you are surprised by this. Well engine braking going down steep grades can do this or steep upgrades with lots of throttle. If you plan to do this a lot look at building a catch can to keep the oil out of the air filter.

[DanielC]

Before all that, is the PCV valve working good?   Granted, if the rings are worn, a good PCV valve cannot Keep up with that, but a goof PCV valve will help, even then.

[EdwardK]

Probably just blowby picked up oil. If you were driving it hard, this will be more evident. 

 

I'm guessing you haven't done a compression test in a while? Might be time to do a wet/dry test and see how it looks. Rings are probably pretty worn. 

 

 

No.

 

If you were running high RPMs and full throttle this is just excess blow by, combustion gasses forced past the rings into the crankcase. They have to go some where and the easiest way out is the valve cover vent hose that is connected to the air filter housing. Now when the motor is well revved up a lot of oil is being sprayed around from the rod and main bearings. If extremely steep, oil can puddle into the front of the oil pan and be whipped into spray by the spinning crankshaft. All this produces a fog of oil droplets that can easily find their way up under the valve cover. On the top underside of the valve cover is a screen to help filter out oil spray and let it drip back onto the head, but if over burdened with too much oil spray and/or too much blow by it will work it's way past these baffles. The blow by will push this oil fog out the valve cover vent and into the air filter where it will puddle.

 

I guess you are surprised by this. Well engine braking going down steep grades can do this or steep upgrades with lots of throttle. If you plan to do this a lot look at building a catch can to keep the oil out of the air filter.

 

 

Before all that, is the PCV valve working good?   Granted, if the rings are worn, a good PCV valve cannot Keep up with that, but a goof PCV valve will help, even then.

 

 

 

First of all sorry for never responding to this.

 

You guys are right, just blow-by past the rings. This engine has god knows how many miles on it and I know the piston rings are about shot. I haven't had any problems since the trips out to the salvage yards.

[datzenmike]

Blow by increases with the load and revs of the engine. Just drive normally to reduce it.