Pcv valve and tailpipe smoke - JeepForum.com
LinkBack Thread Tools
post #1 of 3 Old 08-23-2005, 01:19 AM Thread Starter
Registered User
2000 TJ Wrangler 
Join Date: Jun 2005
Location: Snellville, Ga
Posts: 140
Pcv valve and tailpipe smoke

I am curious as to if a never changed PCV valve (2000 4.0 tj) can cause these things to ingest a little oil. I noticed after blipping the throttle a few times to 4K rpm (no load, wide open, full closed, wide open, full closed.. ) that i get a light amount of burned castrol gtx in the air. This alone dosent bother me, but I wonder if its possible that a 111K mile old PVC valve could be putting a little oil in the intake under very high vacuum.

I havent taken the valve out yet, my air filter and intake hose tube seem to be pretty clean, but the throttle body and inside of the intake is blackened with something that looks like soot, but the soot is dry, and the intake dosent seem to be wet fouled per se.

Im a firm believer that anythings possible, and if a bad PCV valve will vent some oil into the intake only under certain high vacuum conditions that perhaps that oil is completely sucked through and the intake dried out after the engine is shut off and cools down- hence leaving the dry soot inside.

I wonder if anyone else has noticed this or has any ideas. I never replaced my PCV valves or leaky valve cover grommets because I thought that PCV valves were a part of maintenance that could be neglected and a little oil on the valve cover dosent bother me. Apparently though through my readings online youre supposed to replace the valve itself every 15k?

anyone with similar experiences or recommendations?


Blk2kTj is offline  
Sponsored Links
post #2 of 3 Old 08-23-2005, 05:53 AM
Registered User
Join Date: Sep 2003
Posts: 1,552
The 4.0 used a CCV system. Check you air filter to see if oil is getting in there. The rear tube has a metered port. You just need to stick a paper clip up in there to clean out any build up. The valve cover gasket can affect the system. If it leaks more air gets in than the system can handle. The newer engines don't seem to have this problem as the rubber valve cover gasket does a good job.
75SV1 is offline  
post #3 of 3 Old 08-23-2005, 07:32 PM Thread Starter
Registered User
2000 TJ Wrangler 
Join Date: Jun 2005
Location: Snellville, Ga
Posts: 140
oil in breather tube

well I pulled out the rear breather tube and metal fitting in the manifold, and it dripped a little oil out. The entire tube and rear metering device in the valve cover was completely wet.

I guess thats where the little bit of burning oil is comming from. But now Im interested in replacing the metering device in the rear valve cover hole as well as both of the grommets. However, I wonder if replacing the rear metering device will stop oil from comming up into it. It seems like the device is nothing more that a plastic disk with a small hole in it. If there is no system in the metering device to stop oil from getting sucked into it then I suppose theres no reason to replace it.


thanks for the reply

Blk2kTj is offline  

Quick Reply

Register Now

In order to be able to post messages on the JeepForum.com forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.

User Name:
Please enter a password for your user account. Note that passwords are case-sensitive.


Confirm Password:
Email Address
Please enter a valid e-mail address for yourself.

Email Address:


Human Verification

In order to verify that you are a human and not a spam bot, please enter the answer into the following box below based on the instructions contained in the graphic.

Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
Thread Tools
Show Printable Version Show Printable Version
Email this Page Email this Page

Similar Threads
Thread Thread Starter Jeep Forums Replies Last Post
Tailpipe warning!!!!!!! Smallz General Jeep & Off-Road Equipment 3 08-20-2009 08:21 AM
valve cover smoke shawnxj Engines & Drivetrain 2 01-25-2009 06:00 PM
Where did you guys get 2.5" tailpipe from? KeyserGogo Street Jeep Forum 5 04-20-2008 11:33 AM
Tailpipe too near gas tank? Matt in TN Engines & Drivetrain 2 05-29-2006 08:47 AM
tailpipe tech Greencar Engines & Drivetrain 1 12-18-2004 10:21 AM

Posting Rules  
You may post new threads
You may post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are On
Refbacks are On

For the best viewing experience please update your browser to Google Chrome