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Unread 12-06-2009, 10:15 AM   #1
Krayzie949
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PCV Valve on Valve Cover?

I have a 96 Grand Cherokee with an I6. I believe it's the PCV valve on the front of the valve cover. Well there is blow-by going through there and I was just going to put a breather on the valve cover and get rid of piping to the air box/throttle body and just put a cap on that. Is this a bad idea? I don't think it will screw with anything but I'd rather get an answer before I do. Please let me know. Thanks.

Brian

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Unread 12-06-2009, 10:35 AM   #2
Kruzin
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There is no PCV 'valve'...it's just a rubber orafice.
Just get a new one, they're cheap.
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Unread 12-06-2009, 10:44 AM   #3
Turbonut
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No PCV valve on the 4.0, just CCV, or constant crankcase ventilation. Air enters in the front and out the back into the intake manifold. Need to make certain all tubes are open, and that the rear valve cover adapter isn't clogged. The system needs to remain open to disperse the fumes that are created inside the engine.
Here's some reading:
http://www.jeepforum.com/forum/f13/p...-4-0-a-492738/

Cherokee America - My Jeep is Blowing Oil onto the Air Filter!! - - Jeep at Off-Road.com
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Unread 12-06-2009, 06:37 PM   #4
ZJJay
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Perfect timing as I replaced mine just yesterday. I bought my '96 4.0 ZJ two years ago. Soon after buying it I was checking the crankcase ventilation system and found mine wasn't working. The 4.0 doesn't have a PCV "valve" per se. The plastic elbow at the rear of the valve cover is metered and functions similar to a PCV valve. In other words, it has a small hole in the bottom which regulates the amount of vacuum pulled by the intake, not a spring loaded plunger as a PCV valve would. The front elbow, connected by a tube to the air cleaner assembly, allows clean air to enter the crankcase. The front elbow is wide open at the bottom. To test to see if your system is working, remove the hose going to the air filter and put your finger over the end of the hose. You should feel a small amount of suction. That's what the metered elbow and the rear of the valve cover is allowing through. If you have no suction (like mine did two years ago), the rear elbow is plugged. HERE'S WHERE THE PROBLEMS START!

Those old rubber grommets can get real hard, so much that you cannot remove the plastic elbows. When I checked mine two years ago I was able to force a screwdriver under the flange on each side of the CCV (rear) elbow and gently pry it out of the grommet, after squirting some oil around it. I then used brake cleaner and a small drill bit to clean out the orifice. THAT WAS TWO YEARS AGO. I tried to pry out the CCV elbow a couple of weeks ago and it wouldn't budge. In fact, I broke off part of the flange. Humph!

I was already planning on replacing my valve cover gasket, so I decided to do it all in one shot. I bought the valve cover gasket (Felpro P/N VS50458R, $45), then went to the Jeep dealer and bought the CCV elbow ("crankcase vent", P/N 53030495, $13), and two grommets (both elbows take the same grommet (P/N 2946079, $9 each).

I thought I had everything wired. GUESS AGAIN. Removing the valve cover off sounds easy, but is more difficult than it should be. Just follow a shop manual (like Haynes). A couple of tips. The rear elbow might cause enough interference with the cowl that you'll have to break it off just to lift the valve cover high enough to get it over the rocker arms and out. Also, that rear bolt is a bear to reach. I ended up using a 7/16" deep socket, a 2" extension, and a small ratchet (all 3/8" drive).

After I got the valve cover off and cleaned up, I tried to remove the front elbow (which I had planned on reusing) and what was left of the rear elbow. No way, Jose! Those rubber grommets had fossilized and wouldn't let loose of the elbows, even after using oil. I ended up breaking the front elbow too! Another run to the Jeep dealer to get P/N 53030991, $5.

Back to working on the valve cover. I ended up breaking off all of the flange on both elbows just to gain access to all of the gromets. Then used a utility knive to cut the grommets up into small pieces and finally hacked away at them enough to get them and the remains of the elbows out. I would not want to try all of this with the valve cover on the engine. You wouldn't want to drop any pieces down into the valve cover, even though the inside of the top of the cover has a baffle that runs the full length, with only a large opening for the oil filler cap. Besides, it's easier to do this type of work on a bench rather than bending over an engine. Before you reinstall the valve cover, thoroughly clean the surface on the head being very careful not to knock any of that gunk into the head. Also, while you're there, you might as well check the torque on your rockers. Good luck. Just be prepared.
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Last edited by ZJJay; 12-06-2009 at 09:17 PM.. Reason: Making it more readable.
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Unread 12-06-2009, 06:47 PM   #5
CrazyIvan888
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I replaced my CCV elbows, and I'm getting good suction at the rear orifice, and I still have oil coming out of the front tube.
Krayzie, I did exactly what you're considering, using a crankcase breather filter, and I noticed zero ill effects. It's nice not to have oil dribbling onto the air filter! Go for it!
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Unread 12-06-2009, 06:57 PM   #6
Kruzin
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Quote:
Originally Posted by ZJJay View Post
Perfect timing. I replaced mine just yesterday on my '96 4.0. Here's the whole story, and it might take a while, so sit down. (Oh, you're at your PC and already sitting.) I bought my '96 two years ago. Soon after buying it I was checking the crankcase ventilation system and found mine wasn't working. The 4.0 doesn't have a PCV "valve" per se. The plastic elbow at the rear of the valve cover is metered and functions similar to a PCV valve. In other words, it has a small hole in the bottom which regulates the amount of vacuum pulled by the intake, not a spring loaded plunger as a PCV valve would. The front elbow, connected by a tube to the air cleaner assembly, allows clean air to enter the crankcase. The front elbow is wide open at the bottom. To test to see if your system is working, remove the hose going to the air filter and put your finger over the end of the hose. You should feel a small amount of suction. That's what the metered elbow and the rear of the valve cover is allowing through. If you have no suction (like mine did two years ago), the rear elbow is plugged. HERE'S WHERE THE PROBLEMS START! Those old rubber grommets can get real hard, so much that you cannot remove the plastic elbows. When I checked mine two years ago I was able to force a screwdriver under the flange on each side of the CCV (rear) elbow and gently pry it out of the grommet, after squirting some oil around it. I then used brake cleaner and a small drill bit to clean out the orifice. THAT WAS TWO YEARS AGO. I tried to pry out the CCV elbow a couple of weeks ago and it wouldn't budge. In fact, I broke off part of the flange. Humph! I was already planning on replacing my valve cover gasket, so I decided to do it all in one shot. So I bought the valve cover gasket (Felpro P/N VS50458R, $45), then went to the Jeep dealer and bought the CCV elbow ("crankcase vent", P/N 53030495, $13), and two grommets (both elbows take the same grommet (P/N 2946079, $9 each). I thought I had everything wired. GUESS AGAIN. Removing the valve cover off sounds easy, but is more difficult than it should be. Just follow a shop manual (like Haynes). A couple of tips. The rear elbow might cause enough interference with the cowl that you'll have to break it off just to lift the valve cover high enough to get it over the rocker arms and out. Also, that rear bolt is a bear to reach. I ended up using a 7/16" deep socket, a 2" extension, and a small ratchet (all 3/8" drive). After I got the valve cover off and cleaned up, I tried to remove the front elbow (which I had planned on reusing) and what was left of the rear elbow. No way, Jose! Those rubber grommets had fossilized and wouldn't let loose of the elbows, even after using oil. I ended up breaking the front elbow too! Another run to the Jeep dealer to get P/N 53030991, $5. Back to working on the valve cover. I ended up breaking off all of the flange on both elbows just to gain access to all of the gromets. Then used a utility knive to cut the grommets up into small pieces and finally hacked away at them enough to get them and the remains of the elbows out. I would not want to try all of this with the valve cover on the engine. You wouldn't want to drop any pieces down into the valve cover, even though the inside of the top of the cover has a baffle that runs the full length, with only a large opening for the oil filler cap. Besides, it's easier to do this type of work on a bench rather than bending over an engine. Before you reinstall the valve cover, thoroughly clean the surface on the head being very careful not to knock any of that gunk into the head. Also, while you're there, you might as well check the torque on your rockers. Good luck. Just be prepared.
HOLY RUN ON, BATMAN!

Not even gonna try to read that mess.
Learn where your 'enter' key is, and use it once in a while
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Unread 12-06-2009, 07:14 PM   #7
ZJJay
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Good point. I'll try to remember next time. Sorry.
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Unread 12-06-2009, 08:16 PM   #8
CrazyIvan888
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You can always edit the post, throw a few "enters" in there.
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Unread 12-06-2009, 08:30 PM   #9
Kruzin
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Quote:
Originally Posted by CrazyIvan888 View Post
I replaced my CCV elbows, and I'm getting good suction at the rear orifice, and I still have oil coming out of the front tube.
Krayzie, I did exactly what you're considering, using a crankcase breather filter, and I noticed zero ill effects. It's nice not to have oil dribbling onto the air filter! Go for it!
The problem with this is that technically this is part of the emissions system. And if you are in an area that requires inspections, it would fail the visual inspection for removing factory equipment.
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Unread 12-06-2009, 08:35 PM   #10
CrazyIvan888
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Oh, I never thought of that! There's no inspection required where I live, so I never considered that angle.
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Unread 12-06-2009, 09:22 PM   #11
ZJJay
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Thanks, CrazyIvan888. Another good editorial tip I'll remember.
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Unread 12-06-2009, 09:24 PM   #12
CrazyIvan888
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No problem.
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Unread 12-07-2009, 04:03 PM   #13
Krayzie949
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Thanks for all the responses everyone. I'm unsure what I'm going to do yet. I may just put a breather on it and cap it for now as it is cold where I'm at and I don't have anywhere warm to work. I'm thinking of doing this for now and then taking the valve cover off in the spring when it's warmer. Thank again everybody. I love this website.

Brian
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Unread 01-20-2010, 12:58 PM   #14
melk
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Sorry to revive a recently departed thread but I'm lining up projects for my 96 4.0 100k and the CCV is near the top of my list.

The elbows and grommets aren't brittle but I'm having a hard time getting them off. Do you just wiggle and pull them straight up and off? I'd like to inspect and clean them but I probably should just wait until I have replacements just in case they break.


Next up is the valve cover. I've had a fairly loud tapping noise (increases with throttle) the entire 6 months/10k miles I've had the Jeep and I'm worried that it's the valves and they are getting alot of uneccessary wear and tear. Anyone have a link for detailed instructions on how to remove and clean the valve cover? Any other maintenance that should be done while I have it off?

Thanks
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Unread 01-20-2010, 02:48 PM   #15
ZJJay
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First, take a look at my post from 12/7. I suggest you buy two grommets, both elbows, and a valve cover gasket before you begin. Also buy a Haynes manual if you don't already have a Jeep shop manual. It tells how to do the job.

I also suggest you buy a mechanic's stethiscope. Summit Racing has them. With it you can listen to where your tapping noise is coming from. The noise might not be your valves, but your lifters. While you have your valve cover off you might want to change out the lifters. I'll let other members weigh in on that idea.

You might need to use a pry bar (rolling wedge bar) GENTLY to get the plastic rail off that holds the fuel injector wires.

I suggest you remove the valve cover before trying to remove the elbows, unless the rear elbow causes a clearance issue.

It's technically a simple job. It just takes longer than you'd expect.
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Last edited by ZJJay; 01-20-2010 at 03:51 PM.. Reason: correct typo.
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