oil in the airbox, another cause

[mjeff87]

Discovered another cause for my oil soaked air filter aside from blowby. While changing the oil and PMCS-ing the MJ this weekend, I noticed the little vaccuum actuated flapper valve at the bottom of the airbox that lets air in looked like it hadn't moved in ages :roll: No vac signal = no fresh air to the intake. I'm gonna fully diagnose it when I have time, but for now I temporarily blocked the flap WFO. Viola! It's not starving for air now, and not sucking oil laden crankcase vapors back thru the fresh air line that runs to the airbox :D

 

Just something y'all might want to check out if you still run the OEM airbox/filter combo....

 

Jeff

[Bounty Hunter]

Do we need that? I cut that whole thing off the airbox.

[ROADLESS]

Cut mine out too. I also removed the intake silencer/venturi from the airbox. This mod really opens up the airway! http://gojeep.willyshotrod.com/HowtoSilencer.htm :banana:

[Fullsizexj]

did you check the baffle on the valve cover, it is located where the small vacume line attatches, if it gets gunked up, it will cause the oil type steam to be forced into the air cleaner through the larger hose conected to the valve cover into the air box commonly mistaken as blowby

[beaterjeep]

So that's why mine is always covered in oil, I've asked around and been told as many different answers as people I've asked. None of them were what you guys were saying it is. Looks like ya helped more than one person out here.

[mjeff87]

did you check the baffle on the valve cover, it is located where the small vacume line attatches, if it gets gunked up, it will cause the oil type steam to be forced into the air cleaner through the larger hose conected to the valve cover into the air box commonly mistaken as blowby

 

Yeah, it's all clean. I've actually taken the whole top end of the head off (rocker cover, rockers, pushrods, lifters and cleaned them back to bare metal (and plastic)) as well as the vac circuit in the TB and the small vac line from the VC.

My problem is worn valve seals, more than rings on the bottom end...not technically "blowby" but has the same result. I get oil in the filter, as well as oil pushing out from the oil fill cap on the VC :oops: I gots too much positive pressure inside the cover, and that little vac line in the back isn't pulling all of it out and into the TB....

Jeff