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interesting oil leak

dellstopjeep

dellstopjeep

NAXJA Forum User
Location
KUNA, ID
i just picked up an 89 cherokee 4.0 with 150,000 miles on it. motor runs fairly healthy no rod knock and such.....
but it is dumping a lot of oil from an interesting spot. i think i have pinned it down to the air box. not just a little blowby though. i would say a quart a day if i drive it 30 to 40 miles. i know 4.0's leak a bit into the airbox that is normal but any ideas as to why so much on this vechicle. the way the drip pattern is i cant find anywhere else it would be coming from in that area. there is standing oil on the filter and some at bottom of airbox so has to be. i thought maybe the guy had just done a oil change and overfilled but i am at add line so that cant be it.
thanks
 
What happens to really suck oil is the top of the head gets layer after layer of sludge build up, each layer moves the oil pumped to the top of the head closer to the CCV pipes till a certain point where the ccv pipes are submerged in the oil. Then it sucks it up and pumps it to the airbox. The sludge build up also slows the return which adds to the oil level under the valve cover. Only solution is to clean it out either mechanically [fast] or with a cleaner [slower] or with running synthetic oil [slowest and with the amount of oil you are pumping, expensive].
 
dellstopjeep said:
i will clean the ccv tube i saw in a diagram from other post. whats best use pipe cleaners?
Click to expand...

Probably beter to replace the small diameter CCV tubing and orifice, rather than cleaning it. Dealer or NAPA have them, not expensive, part numbers are in recent threads here somewhere. Less than $20 as I recall.

Chlorinated brake cleaner, and compressed air work the best, but elbows are a pain to clean. Mine broke in several places (made it easier to clean) but it has three rubber hose pieces holding together now (Makes it easier to clean, LOL)

New Valve cover gasket and rubber grommets are a good idea too while the valve cover is off. They need to seal good and the small CCV line needs to be clean to stop oil flow into the air filter.
 
i will order up smaller ccv line tonight and then see how that works and then determine if i need to jump on valve cover right away or i can at least not have to park jeep for a while.
 
For your year you should take the valve cover off and clean it up. Inside there are valves in the cover to the holes for the hoses. I think there are screws that hold them in. There are also gaskets under the valves but I never replaced them. Do it carefully and clean well.
 
pulled off ccv line and it has plenty of air goin through it and lots of suction so i dont know if its really necessary to replace that line. but valve cover i will do.
 
dellstopjeep said:
pulled off ccv line and it has plenty of air goin through it and lots of suction so i dont know if its really necessary to replace that line. but valve cover i will do.
Click to expand...

If you have good suction and flow, a 2.2 mm or larger, clean orifice, and no leaks around or on the valve cover gasket or the two gromets and hoses on the valve cover and you still get oil in the air filter, you might have a serious blow by compression problem. That could be confirmed with compression tests on the cylinders.
 
block is clean around valve cover and no major oil around grommets and hoses on top of valve cover. hmm, looks like im kinda screwed huh. i will still pull valve cover off and clean inside. seems weird this thing dumps a lot of oil in airbox. when i have driven for while and park i drop a good thiry drops haha. need compression check huh, if verdict is bad do i need to rebuild motor???
 
was it ever hydro locked? my buddy ran his yj though some water and it sucked it in. Turned the oil into chocolate milk. We did an oil change next day and his started puking oil into the air box. Pretty sure his motor is fried but I don't have the heart to tell him that because he is still paying for the YJ.
 
dellstopjeep said:
block is clean around valve cover and no major oil around grommets and hoses on top of valve cover. hmm, looks like im kinda screwed huh. i will still pull valve cover off and clean inside. seems weird this thing dumps a lot of oil in airbox. when i have driven for while and park i drop a good thiry drops haha. need compression check huh, if verdict is bad do i need to rebuild motor???
Click to expand...

Don't panic yet, just pull the valve cover, clean it up (find and follow a good write up here so you do it right, their are some cautions to follow) and then see what you have. You could also pull one hose off the valve cover, plug the other hose leaving it on the valve cover and see if the open hole is blowing out gas and oil, or not! Hold your hand over the open hole momentarily and see if you feel a lot pressure building and blowing by or not.
 
Damn shame to pull the valve cover. That may be the only Jeep I-6 valve cover gasket that doesn't leak in the country.
 
"Damn shame to pull the valve cover. That may be the only Jeep I-6 valve cover gasket that doesn't leak in the country."

As Yoda once said, "there is another", LOL.:laugh:
 
When you pull that cover off have a shop vac with a crevice tool in one hand. IMMEADIATELY vacum any pieces of sludge that seperated from the cover/head area. To clean the top of the head use a plastic scraper and the shop vac, work them together, you don't want any of that crap getting down to the return galleries and the oil pan. Get enough of that stuff in the pan and it will plug up your oil pump pickup.
 
dellstopjeep said:
motor is toast, well in a nutshell at least i wont go into detail. thanks for help i will now begin hunt for used motor to swap in.
Click to expand...

Awe, come on, we want to hear the toasty (LOL) details, just how toasted was it, and yet it still ran! Can't seem to totally kill these things.

What about running gear oil in it? Some guy here says he is running straight Lucas oil additive in his, and he is still 4 wheelin in it!
 
explain how that works, you can really run gear oil? i will run this motor till it blows probably. i will keep a 12 pack of 20w 50 in the backseat :cheers: it honestly will probably be okay for a long time its just the fact that when you know your rings are shot it bothers ya. but the motor is still fairly healthy, doesnt smoke at all. oh well.
 
here is another question while im also askin about gear oil. elmininating the line and just adding a breather filter, will it help minimize the oil mess by just burning it off through the filter, or will it just make a mess still. i had a breather on a toyota once and oil kinda smoked out when you gave it gas. at least it elminiated oil soaked everything.
 
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