Oil leaking out breather in Valve Cover

[Deerhunter30]

I have a question about my 83 CJ. Whoever had it before me had removed a lot of the vacuum lines, air cleaner, etc. My jeep has a PCV system in the back of the valve cover and one of those K&N breathers in the front. Over time oil will get soaked up into the breather and it will leak out. What can I do? Do I need the breather? What was in that hole from the factory?

 

[Bounty__Hunter]

The PCV system is designed to pull fumes from the rear of the valve cover where the PCV filter is. This creates a vacuum in the crankcase that should then pull fresh air through the breather at the front of the valve cover. If it's pushing air/oil into the breather the PCV is not working properly. Make sure the PCV hoses are in good shape and have vacuum. If that checks out, you may need to remove the valve cover and have a small baffle tacked around the breather hole, to prevent the valvetrain from splashing oil into the hole.

 

[Snitty]

this is a problem that many jeepers are not aware of.. and is quite possibly the only fault in the AMC inline motor design... the PCV system often fails, and routine maintainence on the valve cover and pcv hoses is a great idea in keeping the flow moving properly

 

[Inspector-Gadget]

Hello Deerhunter30,

It is always hard to visualize a pollution control system that has been modified, but I will try to give what information I can.

First, here is how the hoses of your 83 Jeep’s pollution control system were configured when the Jeep left Toledo.

(Note: I know this is a big picture in terms of bytes and screen dimensions, but the picture needs to be large for legibility.)

Originally, your Pollution Control Valve (PCV) system consisted of two hoses, an air cleaning housing filter element and the PC-Valve. The PCV was inserted into a rubber grommet in the valve cover at the FRONT of the engine. The rubber hose from the end of the PCV led back to a source of manifold vacuum at the base of the carb. The other hose attached to the small filter element in the air cleaner box and then led back to a hose fitting which sat in a rubber grommet at the back end of the valve cover.

See diagram, above.

So…fresh air gozinta the engine through the air cleaner filter, through the hose, into the back end of the valve cover, bounces around inside of the engine for a while, then gets sucked out of the engine by manifold vacuum, through the PCV and the attached hose into the base of the carb, to burned in the combustion process.

(How’s that for a run-on sentence?)

That was how things were supposed to work.

The air coming out of the engine will naturally be laden with oil vapor and combustion byproducts because of the inevitable blow-by. Those oily vapors are likely collecting in your K&N breather and condensing back to a liquid upon cooling.

To cure that, I would put the PCV valve back in the front end of the valve cover and connect the PCV to a source of manifold vacuum at the base of the carb. Then move that K&N breather-filter element to the back end of the engine so it filters fresh air going INTO the engine, instead of the oily air coming OUT of the engine.

If that does not stop the oil suction, I would suggest a cylinder compression check. You might have have a case of excessive blow-by, which is forcing an excessive amount of oil out of the engine.

I hope the above proves helpful.

Gadget

 

[Bounty__Hunter]

I always thought PCV=Positive Crankcase Ventilation and CCV=Closed Crankcase Ventilation. Hmmm.

 

[Inspector-Gadget]

You could be right, Bounty. But that might just be a case of, “You say potato, and I say patahto.”

Is there a functional difference?

Gadget

 

[Bounty__Hunter]

I'm not sure how the PCV and CCV systems differ, I just know the newer FI engines have CCV.

If you find out what PCV really stands for, I'd be interested in fnding out.

 

[Inspector-Gadget]

Bounty,

The more I think about it, the more I believe you are correct: that PCV is short for Positive Crankcase Ventilation.

I plead guilty to sloppy use of terminology. Hopefully, the PCV system explanation and tips I gave to Deerhunter above are still correct.



Red-faced Gadget

 

[Deerhunter30]

I'll look at swapping the PCV (which is currently connected to a manifold vacuum source) to the front of the engine and see if that makes a difference.

 

[Bounty__Hunter]

No biggie, it sounded right and I'm not 100% sure on what I always thought it stood for. I think you were right on with your diagram and description, and you gotta love all those vacuum lines :roll:

But, you'd think it would work regardless of which end of the valve cover it was connected to, considering everything else was in working order.

 

[Inspector-Gadget]

Deerhunter,

You might want to replace that PCV-valve also.

As I recall, about $3.00.

Replacing mine magically cured my valve cover oil leak and the rear main seal oil drip.

My "guess" is that the malfunctioning PCV-valve over-pressurized the engine.

Gadget

 

[Inspector-Gadget]

Ever any events near the Seattle area?

Oh!

The reason I suggested moving the PCV-valve back to the front end is because that was the "suction" end of the system as originally designed. There MIGHT already be an oil baffle in place within the valve cover.

SSsshhheessshhh.....all in all, I could have done a much better job of explaining my theory.

Gadget

PS: I think I need a nap.

 

[Deerhunter30]

The PCV valve is new. I'll try the swap theory and see how it goes.