i have a 87 cherokee 4 0 it si filling air box with oil cant figerout y

 

its called blow by and its usually cause by needing to clean the rear pcc valve line going from the rear of the valve cover to the intake. the nipple that's threaded into the intake needs to be cleaned out also. if that doesn't stop it. make a catch can to put in the line going from the pcc valve on the front of the valve cover going to the breather box.

 

I had this problem and just replaced all the vacuum hoses in the area...

NAPA part numbers
BK 7151367
BK 7151366
BK 7151365
BK 7151364
BK 7151363

The bold ones have the parts that I think helped the most.

Also, if my 87 has a PCV valve, I'll be damned if I can find it. I have been told that it is integral inside the valve cover... I don't know for sure.

 

i was told the same i have a 90 i was told that we have the pcc not pcv valve on ours

 

my 91 had bad blow-by and oil in the air filter. I had a couple of vaccum hoses and boots that needed replaced. no more blow-by...

 

I heard that taking the valve cover off and cleaning the orifices really helps too.

 

depends on how bad it is. you could solve it by replacing the piston rings.

 

Have you tried replacing the front valve on the valve cover, the CCV valve that connects to the air filter box. Not sure if it would be the same as my 98