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Topic Review (Newest First)
05-25-2013 01:32 PM
Davers87 I think I just fixed this on my jeep yesterday. Took off the valve cover, cleaned all the sludge caked inside around the valve cover was probably a quarter of an inch thick layer all around pretty bad but I shouldn't have to do it again for a long while. The sludge was blocking the front pcv valve and so the back valve was working as a vacuum pulling oil into the intake.
06-26-2008 07:54 AM
parrot head
Originally Posted by xxcheathamxx View Post
mine does the same thing but i was told that they just did that when it was an overflow and it was normal for there to be some oil.
no, not normal. It is either blocked vacuum lines, pcv or blow by. This just me, but I'd check all the cheap and easy stuff that was mentioned here before I just gave up and said it was blow by. In my case it was the steel vacuum manifold that was so plugged when I bought my 89 4banger that I had to remove it and let it soak in solvent overnight before blowing it out with compressed air. After that, no oil in the airbox
06-25-2008 02:14 AM
Buc Knaked mine does the same thing but i was told that they just did that when it was an overflow and it was normal for there to be some oil.
06-24-2008 09:58 PM
oil in airbox

I had the same problem with my 95 2.4l. The CCV system was not working properly. I removed the small brass fitting on the left side front of the valve cover and found the very small orifice in the fitting was totally blocked with yeek. The flexible hose that connects the fitting/orifice to the plastic vacuum tube that then connects to a fitting on the intake manifold under the TBI was also shot and creating a major vacuum leak. I removed all the pieces, cleaned them all with carb cleaner, ran a small brass bore brush through the fitting in the intake manifold under the TBI, replaced the flexible hose and clamped it to both the orifice/fitting and the plastic vacuum tube. That solved the vacuum leak problem quite nicely and no more oil in the air box. It also seems to have increased the fuel mileage slightly. I think this is an often neglected bit of maintainence and I am sure that mine had not been cleaned in 135,00 miles.
06-01-2008 09:29 PM
4.0l sahara Some times a clogged pcv valve will cause oil to be blown out the breather and seem like blow by even know it isn't. Try replacing the pcv valve.
06-01-2008 08:57 PM
rebelBullDawg325 its a blow by issue. not pcv valve. i've seen 2 91 6cyl do the exact same thing first hand.... on mine i just disconnected from the air box, plugged the hole on the box then lengthened the hose to where it hangs real low and the excess oil drips out. my buddy re routed his hose closer to the throttle body so it would burn it up in the combustion chamber
06-01-2008 07:38 AM
parrot head
Originally Posted by bizzleyj View Post
i jus purchased a 91 wrangler has the 2.5 and the hose from the valve cover that goes to the air box is spitting oil in there,,does any one know ylllll
Check all your vaccuum lines for blockage, especially the metal ones. When I bought my yj 4banger it had the same problem you are describing. It ended up being severely plugged up vac lines.
05-31-2008 12:41 AM
Triple88a what do you mean? the breather is suppose to be connected to the intake so the harmful fumes produced inside the engine can be "vented" into the intake and then burned in the combustion chamber.
05-31-2008 12:27 AM
bizzleyj i installed a snorkel yesterday and just ran a hose from that valve cover breather under the frame so it dosent spray oil everyware,,
05-30-2008 01:31 AM
AzTJ Older Jeeps have PCV valves and newers don't, instead they have a CCV or crank case ventilation which is just the rubber grommet with a small orifice.

To check the PCV, remove it from the valve cover and shake it. If it rattles, it's not clogged. Then with the engine running, put your finger over the bottom and you should feel it sucking.
05-30-2008 12:54 AM
Triple88a i've been wondering that for a while. Whats the difference between the pcv and the breather one. On my old vehicle (havent messed with it on the jeep yet) it was connected to the intake manifold so this tells me that when i let go of the gas it gets vacuum but i dont know if thats right.
05-30-2008 12:43 AM
Dare2BSquare Yeah, that's just a crankcase ventilation hose.
05-30-2008 12:22 AM
Triple88a Az, isnt the PCV all the way back by the firewall?
05-30-2008 12:17 AM
AzTJ Check the PCV valve that the hose is connected to on the top of the valve cover. When they go bad they let blow-by through.
05-29-2008 11:43 PM
crafty With any luck it is something minor. I had a 92 before with a 4cyl that lost compression due to being worn out. One of the engines I tried to replace it with had severe blow-by. Pumped it into the airbox, up the dipstick tube never seen 1 that bad. Rebuild time or NEW engine if it is not something minor Don't waste your time with salvage yard engines like I did. 4 times to find a descent engine in the salvage yard, not worth it IMHO.

A little oil can be considered normal.
05-29-2008 10:41 PM
Triple88a is it clogged? Pull the breather pipe out and check it out. I have the feeling thats its clogged and there is just a small hole left so it sucks the oil up.
05-29-2008 10:24 PM
air box full of

i jus purchased a 91 wrangler has the 2.5 and the hose from the valve cover that goes to the air box is spitting oil in there,,does any one know ylllll

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