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Old 04-21-2010, 10:27 PM   #1
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PCV Valve?

So my TJ has been running really rough and stalling randomly. I changed out the plugs and wires and the distributor cap and rotor. I was looking at changing the PCV Valve however I can't seem to actually find the valve at a parts store or online?! According to the trusty Haynes manual, there is an actual PCV Valve that can be changed out. Can anyone provide a little guidance on where I would be able to find said valve or if I really don't need to replace it?

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Old 04-21-2010, 11:08 PM   #2
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Checked a couple of vendors for ya. No PCV Valve. Not with Standard Motor Products or Hastings Filters. Might try your nearest Chrysler/Dodge/Jeep dealer.

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Old 04-22-2010, 12:44 AM   #3
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The purpose of the PCv system is to suck fumes out of the crankcase and burn them.
The valve was put in the line in case of backfire - if there was an explosion in the intake it would slam and prevent flame from getting in the crankcase.

TJ's etc with the 4.0 do it differently. There is a long small plastic vacuum line that runs from the intake to the filler cap at the back of the engine. At the cap end, it has a small calibrated restriction - as I remember, it's about .060".
That's it. No more valve.

It's not going to cause rough or stall either.

Look for an unplugged vacuum line somewhere else.
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Old 04-22-2010, 01:21 AM   #4
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As Rich stated, there really isn't a PCV valve for TJ's.

Try thoroughly cleaning the inside of your throttle body with a can of aerosol throttle body cleaner. The IAC (idle air controller) that feeds all of the engine's air into the engine at idle when you're not stepping on the gas might be sticking and not letting enough air into the engine at idle. The IAC is bolted onto the passenger-side of the throttle body and it gets its air for the engine through the slot on top of the throttle body's butterfly valve plate that is closed at idle. Make sure some of the cleaner gets into that slot (idle air control passage inlet) as you can see in the below illustration. The engine needs to be running while you do this, simply hold the rpms up a tad while you spray into the throttle body. Complete instructions will be on the back of the can.

This is a common issue for the IAC to get dirty and clogged up on TJ's. Simple fix anyone can do.

Here is a picture of the TB and the location of the IAC.

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Old 04-22-2010, 07:14 AM   #5
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Thanks for the help guys! Interesting that there is no PCV on these models. It is shown in the trusty Haynes manual but this isn't the first thing in the book that hasn't been accurate for the 99 model.

The shop checked all the vacuum lines and said they couldn't find anything wrong. They also cleaned the IAC. I will try that again. Hopefully this was an easy fix of just putting in a new dist cap and rotor. We'll see what today brings. Thanks again!
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Old 04-22-2010, 09:53 AM   #6
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Quote:
Originally Posted by Big_B View Post
Thanks for the help guys! Interesting that there is no PCV on these models. It is shown in the trusty Haynes manual but this isn't the first thing in the book that hasn't been accurate for the 99 model.

The shop checked all the vacuum lines and said they couldn't find anything wrong. They also cleaned the IAC. I will try that again. Hopefully this was an easy fix of just putting in a new dist cap and rotor. We'll see what today brings. Thanks again!
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Old 04-22-2010, 11:30 AM   #7
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I have to agree. I pick up the actual shop manuals on e-bay for all our vehicles.
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Old 04-22-2010, 01:43 PM   #8
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I would never waste my $$$ for a Haynes or Chiltons manual. They are too general, try to cover too many model years in one thin manual, and have too many inaccuracies. The Mopar factory service manual is the only error-free and totally complete and useful manual you're going to find.

What model year and engine do you have? Exactly what plug brand and model # did you install?
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Old 04-22-2010, 02:42 PM   #9
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Originally Posted by Jerry Bransford View Post
What model year and engine do you have? Exactly what plug brand and model # did you install?
Quoted for emphasis.

Using the wrong plugs are notorious for causing hell. and you can't trust the morons behind the counters to give you the "right" ones most of the time.

EDIT: Jerry, his Jeep profile says 1999 4.0L....and post says distributor cap/rotor.....
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Old 04-22-2010, 02:49 PM   #10
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Originally Posted by mrcarcrazy View Post
EDIT: Jerry, his Jeep profile says 1999 4.0L....and post says distributor cap/rotor.....
I see that now. What is wierd is that I already checked his profile but depending on how you do that, you get two different results.

If you do a simple left-click on it, which I didn't do the first time, you get his profile that shows his Jeep's profile. But if you do a right-click and tell it to open his Profile in a new window as I did the first time, it only shows a collection of Jeep photos and nothing about his Jeep profile. Wierd!
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Old 04-22-2010, 09:39 PM   #11
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Gents,

Again, I appreciate all the help as this is my first Jeep.

My rig is a 1999 Sahara edition with the 4.0L I6 engine. I put Autolite plugs (not sure of the model number) and wires in it from AutoZone. They told me the gap should be .035 which matches the Haynes and anything I have found online. The cap/rotor I put is is BWD Z-series from Advanced Auto Parts.

Thanks for the heads up on the manual. I completely agree that this this is useless. Maybe someone else wants it on ebay? I will look for a true shop manual for my Jeep.

So...can anyone tell me what this part is that I have circled in red? My buddy insisted that it is a PCV even though I told him it is not. He gave it a good tug and broke it. Now I need a replacement... any thoughts? Thanks again!
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Old 04-22-2010, 11:46 PM   #12
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^^^^ Vent tube for the valve cover. Why the hose goes to the intake.
The plastic 90* piece is just a connector, it is empty//hollow...Just used to connect the hose to the valve cover is all. They are cheap, just a few bucks at any auto store.

NOT a PCV valve. <<< so you can rub that in your buddies face.
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Old 04-23-2010, 05:35 PM   #13
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Since Big B posted a pic of it, can anyone say why I would have oil coming out of my vent hole that was just mentioned in his picture? Or where else would oil be coming from to be running down my valve cover and onto my manifold, then on down over an O2 sensor and onto my exhaust pipe. Mmm I love that smell!!! I've checked my oil filler cap and it "seems" to be in good shape, the elbow going connecting the vent tube seems snug enough as well... Any ideas?
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Old 04-23-2010, 08:50 PM   #14
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^^^^ Vent tube for the valve cover. Why the hose goes to the intake.
The plastic 90* piece is just a connector, it is empty//hollow...Just used to connect the hose to the valve cover is all. They are cheap, just a few bucks at any auto store.
Every part store knows what I'm talking about...none carry it! Off to the dealer tomorrow morning to see if they can hook me up! Still doing the stalling thing. Hopefully this weekend I'll be able to get to the bottom of it.
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Old 04-23-2010, 09:22 PM   #15
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Quote:
Originally Posted by chrisb0108 View Post
Since Big B posted a pic of it, can anyone say why I would have oil coming out of my vent hole that was just mentioned in his picture? Or where else would oil be coming from to be running down my valve cover and onto my manifold, then on down over an O2 sensor and onto my exhaust pipe. Mmm I love that smell!!! I've checked my oil filler cap and it "seems" to be in good shape, the elbow going connecting the vent tube seems snug enough as well... Any ideas?
The circled part supplies fresh air to the crankcase that is then sucked out by the orifice in the rear valve cover insert. Check to see that the orifice is not plugged and that you have vacuum to it.
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Old 04-23-2010, 09:29 PM   #16
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Every part store knows what I'm talking about...none carry it! Off to the dealer tomorrow morning to see if they can hook me up! Still doing the stalling thing. Hopefully this weekend I'll be able to get to the bottom of it.
This appears to be it:

Store Locator | NAPA Online
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Old 04-24-2010, 08:49 AM   #17
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I just got the same vent tube in the mail yesterday. The guy that owned my TJ before. me cracked the elbow off, and I noticed oil all around it. On a thread on here or JF someone mentioned that if the elbow in the back of the valve cover is clogged it causes back pressure which is why you see oil around the front one. So I just replaced both elbows, and grommets. Found them at Rock Auto

RockAuto Auto Parts

Part #'s

Front elbow - Dorman 47079
Back Elbow - Dorman 47057
Grommet - Dorman 42344

They call everything a PCV, but whatever. It got the job done. Hope this helps.
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Old 05-17-2011, 10:17 AM   #18
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Originally Posted by Big_B View Post
Gents,

Again, I appreciate all the help as this is my first Jeep.

My rig is a 1999 Sahara edition with the 4.0L I6 engine. I put Autolite plugs (not sure of the model number) and wires in it from AutoZone. They told me the gap should be .035 which matches the Haynes and anything I have found online. The cap/rotor I put is is BWD Z-series from Advanced Auto Parts.

Thanks for the heads up on the manual. I completely agree that this this is useless. Maybe someone else wants it on ebay? I will look for a true shop manual for my Jeep.

So...can anyone tell me what this part is that I have circled in red? My buddy insisted that it is a PCV even though I told him it is not. He gave it a good tug and broke it. Now I need a replacement... any thoughts? Thanks again!
Mine broke after a hard tug, too. It's probable never been replaced on my '99. I found this thread about removing the valves, and thought I would post here for reference. I'm about to go test this procedure now.
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Old 05-18-2011, 12:16 PM   #19
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Got the job done, but the method in that thread didn't help me very much. I cut away about 1/8 of the grommet, jammed a flat head between the grommet and the vent, and used that as a lever to pull the vent out. Destroyed the grommet, but the vents came out easier than any other method I tried.

I couldn't find the vent at 4 different autoparts stores. The grommet was a little easier, but no store had more than 1. So I spent $20 on two grommets and a front vent at the dealership.
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Old 05-18-2011, 12:43 PM   #20
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If you look at the haynes manual, its basically a YJ book with a couple of pictures thrown in for the TJ's... 85-06 is a lot of different wranglers to cover...
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Old 05-18-2011, 08:32 PM   #21
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The front hose is the fresh air return line. Vacuum sucks the gases out of the rear hose. If the rear hose, which is acting as a PCV valve, gets clogged, the gases are forced out the fresh air tube, causing oil around the grommet and possibly oil getting into the intake. Same thing happens with a PCV getting stuck closed. With a PCV, the more gas you give it, the more restricted the valve is. At WOT the PCV is closed causing the gases to escape through the fresh air line. Thats why you see a lot of hot rodders running a vent filter on the fresh air side of the engine, or installing a catch can. Otherwise they suck a whole lot of oil into the intake.
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Old 08-24-2011, 01:35 PM   #22
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I just got the same vent tube in the mail yesterday. The guy that owned my TJ before. me cracked the elbow off, and I noticed oil all around it. On a thread on here or JF someone mentioned that if the elbow in the back of the valve cover is clogged it causes back pressure which is why you see oil around the front one. So I just replaced both elbows, and grommets. Found them at Rock Auto

RockAuto Auto Parts

Part #'s

Front elbow - Dorman 47079
Back Elbow - Dorman 47057
Grommet - Dorman 42344

They call everything a PCV, but whatever. It got the job done. Hope this helps.
My '04 Sport has been leaking and leaving stains for over a year now, so this has been long over due.

Thanks for the part number info, I just bought them off of RockAuto; pretty sure I wouldn't have been able to find them without the help. Here is the pricing info just for FYI purposes.

Dorman (PCV) Elbow 47079 - $2.81
Dorman (PCV) Elbow 47057 - $3.08
Dorman Grommet 42344 - $2.18 per unit (I bought 4 of these just in-case I destory it during the install)
Shipping $5.31
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Old 09-19-2011, 01:46 PM   #23
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OK, I'm new to wrenching on my Jeep, and ran across this forum - which has been a huge help. Anyways, I was doing a search a couple of weeks ago to try and find a Haynes or Chilton's manual for my 04 TJ (no store in my area had one) and ran across this site:
Auto service & repair manuals: 2004 TJ Jeep Wrangler Repair Manual

Someone has gotten ahold of the PDF of the Factory Manual and posted it for free. I was skeptical at first, so I downloaded it on my work computer (in case it was a virus, or something.) Turns out it is legit. I used it last week-end to change my first set of spark plugs. Good job to whomever posted it. Just wanted to pass this along, since the discussion above talked about how terrible the other manuals were.

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