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Discussion Starter · #1 ·
took the airfilter out of the cherokee today and the thing is soaked in oil and the box is full of gunk and so is the throttle body.
Its a 4.0l with 270000 on it...
What is this caused by...do these things have a pvc valve somewhere else since theres non on the valve cover...
Dont have a manuel for it yet so i cant look it up.
 

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Discussion Starter · #3 ·
Thanks for the links ...but we found them actually after i posted this.....That was the problem

the one little line was plugged and the little valves were all the way open..

Hope that this encourages everyone with a 4.0l to check so that they dont end up with the same problem...

Thanks again....that was sure a good article....the only one on the internet we could find.
 

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I had blowby on my 4.0 HO and tried both the valve cover cleaning 'trick' (I really don't know how this would solve anything) as well as the PCV valve and vacuum line 'upgrade'. Although there was some improvement it certainly didn't solve the problem and I was still getting about 250 ml of oil in the airbox every tank or so of fuel.
Using scrounged rubber tubing and the plastic tubing from the charcoal cannister I extended the breather tubing to the fender side of the airbox and installed an oil 'recovery jar' inline. This is a 1 litre calf feeding bottle I picked up at Princess Auto. I created an inlet and outlet by cutting into the nipple. So now, before the breather can vent the oil into the airbox, it first must pass through the catch jar eliminating about 90% of the oil.
Restricting the crankcase vent simply forced oil out every place it could (dipstick tube, oil fill etc.) and simply venting it to atmosphere created a nice oil fog and smoke cloud everywhere along with the environmental issues that result.
Ultimately the engine is tired and unless you want to rebuild it immediately then I think the catch jar is the simplest route. I have been told the 4.0 will run forever in this condition and although I hate 'Mickey Mouse' solutions I am going to see how well this works out.
Good luck.
 

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Discussion Starter · #5 ·
Hey that is a great idea... Well have to see how it goes and keep an eye on the airbox situation..

Are those metal flaps that are in those weird valves under the valve cover supposed to be bent uP???

i thought that they might have to be bent down bu will correct it if it isnt easily enough/..

Thanks for the great info....i think that your right in that the engine is tired...270000 on it now so i thnk that your idea will be used..
Thanks again..
 

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The restrictor plates only fit one way. Into the snorkel so down once the valve cover is in it's correct position.
Did you have much carbon build up (an indication of worn rings) or tar and can you understand how cleaning these would stop blowby or "give more power" as the write-up indicated?
 

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Discussion Starter · #7 ·
yah there was a lot of buildup and gunk in the little tubes but not that much at all under the rest of the cover or top of the head....

It should give more power because then you wont restrict the air so much and the pressure wont build forcing air out of the seals.

though you may gain a bit of power it wont be anything noticable...1 horse wont make you stick to the seat when you give her.....only a dyno will show a change in power.
 
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