YJ 4 cyl oil coming out of dip stick

[crimsonride]

So my YJ (2.5 4 cyl) has oil coming out of the dip stick. (Miss managed blow by right?) The engine is fairly new with about 20K after a rebuild.

So I checked the PCV valve and I'm not certain exactly what to be looking for. I have two rubber hoses going in to the valve cover. One is a small 3/8" line going in to the side on the front of the valve cover and leads to the intake manifold for vacuum. It's getting good suction and the fitting is not plugged.

The second is in the top of the valve cover to the rear.....looks like a PCV valve but is actually just a fitting, no "valve" to it at all.... just a clear passage. Anyway, this hose just runs up to a little breather valve like what you would find on a axle vent line. The intake box has been removed and now it's just a hose running to an air filter behind the headlight.

When I removed the vent and plugged the second hose with my thumb I felt vacuum....although it wasn't super strong.

Any thoughts?

Should I tap the second hose in to vacuum as well?

I'm swapping in a new engine later this year so I'm not super concerned about this one but it would be nice to not have it caked in oil every time I take it out.

-Chris

 

[gatchmo5710]

On my straight 6 I T'd both lines together than into intake box(instead of intake manifold) and put new valves on both. Never had a issue. I would blow through lines to verify no clogging. Its shouldn't need vacuum to keep dipstick from blowing.

 

[Gravy]

If both vents are going to the valve cover I'd assume you need vacuum to both.

That's lower crankcase pressure you've got going on and you shouldn't need vacuum to the top end to keep the bottom end from blowing oil out the dipstick.
Something is pressurizing the bottom end.
Have you got good compression? Or a worn ring that's causing blowby?

 

[crimsonride]

I haven't checked compression.... haven't really cared all that much since I'm planning on swapping it but I guess I could look in to it. Normally I think one of the vent lines runs to vacuum and the other runs to the intake to recirculate the fumes. The weird thing is that when I plug the vented line with my thumb I get vacuum, not pressure.

Wouldn't crank case pressure push up through the drain holes of the head and manifest itself in the valve cover as well? Some blow by is common on all engines.... excessive blow by is bad. Usually you can check it by pulling off the oil fill plug and plugging it off with your hand.