Compression Question

Howdy All,
Specs:
88 MJ, 4.0L, 5speed, 4X4

I have a 95 97 VC on it, allow it to vent into the airbox. Milky oil is coming from it saturating my air filter. Milky oil is also present on the oil fill cap.
Plugs are all burning equal, no visible bad signs there.
Coolant is super green. No loss of coolant is visible.
Oil is fine. Performed an oil change, drove it a hundred miles, no sign of coolant in it.

Compression specs:
Cylinder Dry Wet PSI Difference
#1 110 125 +15
#2 130 140 +5
#3 120 140 +20
#4 125 130 +5
#5 135 135 +0
#6 90 105 +15


Looks I have a ring issue in Cyl#6, but that doesn't explain the milky oil. Any idea's?

Thanks in advance!

I currently ran the front VC hose to dump outside of the box, not inside. I'll go thru all the vac lines soon.
I also plan to pull the rear CCV elbow on the valve cover and check if the metering hole on the bottom is clogged. This plastic hose goes from the rear CCV elbow to the intake manifold. I'd like to think I could eliminate it altogether.

Milky Oil = water moisture + Oil

From the look of your compression numbers along with the hydrated oil, I'd be willing to bet you have a very mild blown head gasket. I don't know much about the MJ specific 258 but if the oil filler neck is long leading down into the valve cover it may just be that the cover isn't getting hot enough and water vapor from combustion is getting into the oil. I would make sure your crankcase vent is good and clean and that your PCV valve is in good shape.

Regardless, sounds like a relatively minor issue.

The oil fill cap screws right onto the VC. That shows some milky residue along with the front elbow hose is blowing it out.

I may just pull the VC and check everything under it. Can't hurt, right?

Nope, can't hurt at all. While your in there what about checking the torque on the head? Maybe it is loose in the rear?

Good call, might as well.

Hell, while you're checkin, just throw in another head.

Ya got one? I don't. Felpro VCG is only $5, and my examinations are free

sooooo

What did you find out?

Hubie wrote:sooooo

What did you find out?

Heh, never even opened it up yet.