Excessive crankcase pressure? Oil comes out oil full cap

[E4Marty]

Just today this started occurring on my 86' 2.5l. There's alot I pressure out the oil fill cap, makes a high pitched whistle and lots of blow out when I uncap it. Oil coats the valve cover and side of throttle body after driving. I don't notice a loss in power, or any oil burning out tail pipe. The truck can hardly stay running at idle.

[Rymanrph]

I had a '91 4.0 in my Wrangler that would blow oil out of the dip stick and it was because of poor maintenance. All the oil passage ways were clogged and sludged up. I assume the oil was rarely changed with any frequency. I removed the valve cover and cleaned out what sludge I could. I then ran a light engine flush and changed the oil several times. I still had to run an oil catch can but it wasn't nearly as bad as before the flush.

[Jeep Driver]

You need to remove the cover and clean it as the other guy suggested. Replace your vacuum and vent tubes and grommets.

 

I also used Ultra Black around the grommets at installation. You can tape it off for a clean look when you are done.

 

 

Clean clean clean and it will stay clean.

 

 

It's gotta breath.

[E4Marty]

Well i got it fixed. Boneheaded move on my part, plugged off the hose that normally would attach to the aircleaner box. So realizing my dumb move and not wanting to have an open line I rigged it to attach to the cold air intake. Should have tracked the line instead of immediately plugging it.