CCV issues, why is there positive pressure??
CF Veteran
Joined: Aug 2011
Posts: 10,489
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From: Nor-Cal Coast
Year: 90,84
Model: Cherokee
Engine: 4.0,2.5
When that plugs up inside where you can't see it, crank-case pressure will make it try to blow oil out everywhere. Rear main, ect. You might do an oil change and try that product, Restore. Their is a small chance than might help worn rings. Idk, maybe just''Snake oil". If you DO try it be sure to let us know!
CF Veteran
Joined: Mar 2010
Posts: 47,923
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From: Broward County Fl.
Year: 1989 xj sport 2dr
Model: Cherokee
Engine: 12 hole bosch Injectors
Thread Starter
Member
Joined: Sep 2013
Posts: 101
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From: Machias, Maine
Year: 1989
Model: Cherokee
Engine: 4.0
I've realized that the issue is not so much of the oil, it's also the fact that I just pulled off the new hose, and blew through it and straight water came out. A good amount of it. How could so much moisture be accumulating in the valve cover? Would that be my gasket?
Herp Derp Jerp

Joined: Nov 2011
Posts: 18,251
Likes: 17
From: Parham, ON
Year: 1999
Model: Cherokee
Engine: 4.0L OBD-II
Depends on driving habit. If you only do short little trips water can build up and not completely evaporate as the engine doesn't stay at temp for a long time. Of course it could also be coolant lol
CF Veteran
Joined: Aug 2011
Posts: 10,489
Likes: 24
From: Nor-Cal Coast
Year: 90,84
Model: Cherokee
Engine: 4.0,2.5
The CCV valve has a 2.6mm orifice, an anti-backfire valve, and a function that closes it off under extreme vacuum. Idk what makes that Closed Crankcase Vent different than Positive Crankcase Ventilation besides maybe it closing off under high vacuum. (not even sure a PCV won't do that!)
Agreeing with Salad, venting any moisture is part of what it is for. With the right 195* t-stat running at temp for a while should vent normal moisture.
Agreeing with Salad, venting any moisture is part of what it is for. With the right 195* t-stat running at temp for a while should vent normal moisture.
Last edited by DFlintstone; Dec 9, 2013 at 09:39 PM. Reason: not even sure
Herp Derp Jerp

Joined: Nov 2011
Posts: 18,251
Likes: 17
From: Parham, ON
Year: 1999
Model: Cherokee
Engine: 4.0L OBD-II
CCV systems in our engines have air constantly being drawn through them. PCV systems with a valve are normally shut and only release gasses when a certain pressure is hit. I imagine PCV system is inherently better as atmosphere isn't always flowing through it, reducing methods for contaminants to enter and condensation. Pretty sure any engine built in the last twenty years is all PCV jazz. However it sure is handy if you have a problem with the IAC!
I've realized that the issue is not so much of the oil, it's also the fact that I just pulled off the new hose, and blew through it and straight water came out. A good amount of it. How could so much moisture be accumulating in the valve cover? Would that be my gasket?
CF Veteran
Joined: Aug 2011
Posts: 10,489
Likes: 24
From: Nor-Cal Coast
Year: 90,84
Model: Cherokee
Engine: 4.0,2.5
How about "Continuous Crankcase Ventilation" for A CCV valve ?
Last edited by DFlintstone; Dec 8, 2013 at 11:55 PM.
Thread Starter
Member
Joined: Sep 2013
Posts: 101
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From: Machias, Maine
Year: 1989
Model: Cherokee
Engine: 4.0
I'm pretty sure a PVC sucks pretty much whenever there is manifold vacuum. That Positive Crankcase Ventilation was an improvement over a draft tube since "positive" ventilation cut down on sludge, moisture, and maybe acids building up. Some just had steel wool like stuff in the oil filler cap to filter any incoming air. Then it changed to a hose to the air cleaner.
How about "Continuous Crankcase Ventilation" for A CCV valve ?
How about "Continuous Crankcase Ventilation" for A CCV valve ?
The moisture seems to be coming from the crankcase, as the blowby condenses into the airbox. (which in theory should have negative pressure) So at least the moisture is making it into the filter rather than my engine.
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Joined: May 2012
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From: Lost in the wilds of Virginia
Year: 1998 Classic (I'll get it running soon....) and 02 Grand
Model: Cherokee (XJ)
Engine: 4.0
The moisture is STARTING in your engine. It starts in the cylinders and is blowing past the rings down into the guts, where all those nice bearings live, and your reservoir of oil. What fun! Water in your engine!
When you first start your engine, it's cold, and that steam (in the true sense of the word, the invisible stuff) gets cooled to water vapor and can condense on the interior of your engine, which causes it to accumulate in your oil, get in your bearings, etc. Some gets drawn out through the crankcase ventilation system.
When you run the engine hot enough and long enough, that nice big block of iron and all those other engine pieces and the air inside your engine get all heated up and keep the majority of the moisture in steam form, which then gets pulled out by the ventilation system and eventually goes into the atmosphere where it can't hurt your engine.
This is [part of] why it's very hard on an engine to do a lot of short trips, instead of long one.
You can see this in action at your exhaust pipe on a cool day. When the car is cool, you'll see plenty of water vapor coming out of the tailpipe. (Many people mistakenly call this "steam".)
Once the car warms up, you don't see it anymore. Why? The engine and exhaust system gets warmed up, and is no longer cooling the steam (which is invisible) to water vapor (which is visible). It hits the atmosphere as steam, and quickly dissipates before it can condense to water vapor.
That ain't good!


