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Unread 10-29-2012, 08:52 PM   #1
Barrin
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1998 TJ Wrangler 
 
Join Date: Oct 2012
Location: Clarion, Iowa
Posts: 45
oil soaked air filter

89 mj pioner 4.0 AT 2wd 236,000 miles...
my engine air filter keeps getting saturated with oil...
every oil change I have to rotate my airfilter or buy a new one...
it is stock air intake and stock air filter.
any ideas?

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Unread 10-30-2012, 08:14 AM   #2
cruiser54
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1990 MJ Comanche 
 
Join Date: Oct 2009
Location: Prescott, Arizona
Posts: 10,246
Yep. Your CCV hoses and/or fittings are clogged. The biggest problem is with the one from the rear of the valve cover to the intake manifold. Make sure those is clear by removing it completely and blowing through it. Look at the intake manifold fitting and make sure it's not alll carboned up.

Here's something else to do afterwards if you feel so inclined. It's a suggestion from the factory that was never published in a TSB to my knowledge.

Cruiser’s Valve Cover Mod

Most early and even later Renix 4.0s could be bothered by excessive oil in the air cleaner box. A fix from my old days as Service Manager at a Jeep dealership follows. Information was provided to me from a buddy at JeepTech during those days. I don’t believe it ever came out in a Technical Service Bulletin.


Remove the valve cover and turn it over. Next, remove the fluted tubes that are now facing you by removing three screws on each. Chop 1 inch off each of them. Then, about a half inch up from the area where you just sawed them off, drill a half inch hole in the tubes so the holes will face the rear of the valve cover. Clean and de-burr/sand all rough edges nicely, clean with solvent, and reinstall. Don’t be concerned about the chintzy gaskets that will probably crumble into oblivion when you remove the fluted tubes. They can go back together without gaskets.
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Unread 10-30-2012, 06:25 PM   #3
Barrin
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1998 TJ Wrangler 
 
Join Date: Oct 2012
Location: Clarion, Iowa
Posts: 45
sweet... im checking that out this weekend thanks.
oh and to try and fix this problem I coustomized a pcv system (that didnt work) and cant remember how or where my vac hoses are supposed to go like factory.
I keep looking for a detailed pic of an 89 4.o vac diagram or pic of someones oldeer engine but Im the only one I know of who drives an mj.
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Unread 10-30-2012, 08:21 PM   #4
cruiser54
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1990 MJ Comanche 
 
Join Date: Oct 2009
Location: Prescott, Arizona
Posts: 10,246
Quote:
Originally Posted by Barrin View Post
sweet... im checking that out this weekend thanks.
oh and to try and fix this problem I coustomized a pcv system (that didnt work) and cant remember how or where my vac hoses are supposed to go like factory.
I keep looking for a detailed pic of an 89 4.o vac diagram or pic of someones oldeer engine but Im the only one I know of who drives an mj.
Here you go.
vac-diagram.jpg  
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Unread 10-31-2012, 07:37 PM   #5
Barrin
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1998 TJ Wrangler 
 
Join Date: Oct 2012
Location: Clarion, Iowa
Posts: 45
thats going to help out great... thanks for the diagram.
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Unread 11-02-2012, 01:17 AM   #6
DonBC
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1989 MJ Comanche 
 
Join Date: Jan 2011
Location: Gabriola, British Columbia
Posts: 34
It may be all sludged up under the valve cover and the oil can't get back to the crankcase quickly enough and it gets pulled over by vacuum to the air filter. The routing of the passage ways within the valve cover do not help the problem. That was a problem with mine when I got it. I don't think that the previous owner ever drove it on any long highway trips. It was so bad that when I was stopped for a time at a traffic light it would pull oil over into the intake manifold and then lay down a huge cloud of smoke when I took off. After a major cleaning my problem stopped. At 236k miles yours may have a bit of blowby as well which will amplify the problem.
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Unread 11-02-2012, 05:58 PM   #7
Barrin
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1998 TJ Wrangler 
 
Join Date: Oct 2012
Location: Clarion, Iowa
Posts: 45
yeah, my front cylinder is the problem one... I checked my compression and all are at 130-140 and the front one is 95, so I put it at tdc and blew air into that sparkplug hole and it was comming out of my exhaust pipe...
so, I got a little work to do this winter...I could just grind the valves and change the gaskets ( I got a felpro gasket kit )... but I should just rebuild the thing compleately, it wouldnt cost that much more for the parts... just more time...
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