I have an 05 3.7L 4x4 KJ, and I took it in for an oil change at 35,2xx at Jiffy Lube (I know). They pulled out the plastic baffle piece in the filler tube and it had dense mayonaise-looking residue all over the length of it. Even worse, this piece was dripping something that looked like water and my coolant was 1-2qts low. I had only run the car long enough to get it to operating temp since the oil place is near my work (it has been 20's-30's here lately).

Anyway, they cleaned the crap off, put 50/50 in the coolant, and changed the oil. I called the dealership and they said they'll look at it next week. Has anyone else had this issue? From what I understand, it could be an emulsion of oil and water caused by condensation on the cool plastic parts or a leaking head gasket that is allowing coolant into the oil system. I'm hoping for the former.

My Libby has had a rough time in the last year from random tire marks appearing on my front bumper, hitting a dear and needing frame and body work (nobody was hurt, and the deer got up and ran away eventually), and getting vandalized by some punk kids with chunks of cement so more body work. I got new Bridgestone 695 A/T 245/70R16's last weekend to replace my balding oem wrangler 225/75R16's.

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LOST Mid-Atlantic #071463
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2K5 3.7L Sport in Patriot Blue w/ bug deflector
+ slush mats + JVC 12 Disc changer and HU
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Coming Eventually:
Custom built fiberglass enclosure with two 12" 1000W DHD subs and one 12" 400W Orion sub with an 1800W Legacy amp and a 600W Boss amp

Been lots of discussion on here some get some dont depends on how much you drive etc. Bit it sounds like what a lot of people have been getting, just clean it out and run it.

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MUDD'S MOTORSPORT'S We do IFS lift installs ,
03 OVERLAND EDITION /Kilby-Skidrow-Mopar-4XGuard skids/ 2.5 inch TOTAL CONTROL JBA coilovers -JBA Arms/MOABS-31 FALKEN WILDPEAK AT3W / 4.10's etc, 04 Kilimanjaro Edition loaded, plus 05 KJ limited

#1, it's most likely just condensation which mixes with the oil and doesn't cook off if you just take a lot of short trips and, #2, do not deal with a Jiffy Lube. If your coolant was 1-2 quarts low, it was most likely due to a leaky hose/hose clamp.

There's been reports of the KJ sliming up the oil filler cap when driving only in cold cold weather.

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L.O.S.T forever!
Silver 2002 Skoda Fabia TDI, 235,000km
Former car: Jeep KJ 2003 CRD

DIESEL - saving millions of liters of petrol every day!

I had the same problem. I ran a engine flush through just to make sure everything was cleaned out. When I drained the oil, it was straight black, no moisture.

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OH NO! I THINK WE NEED SOME "OH SH*&T HANDLES!!!!
KJ gone.
New ride
05 Rubicon Unlimited, mostly stock.Starting to add stuff.

as indianrefining already said .. it is the condensation.. I had the same with my 3.7 on my '06 KJ.. and also my'02 ram with a 4.7... I thought something was wrong like I thought I had a coolant leak. but when I did some talking to some folks I found it was just the condensation.. I guess it might come from the pcv filter or something.. guess thats why they added the plastic thingy.. when they ditched the magnum series engines..

overnite temps around here hitting 15-17 range but no problems on mine.

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Peace Through Power.

2002 Liberty, salsa red
1997 Wrangler, dark green

PSN ID: David_Lucas (Burnout: Paradise, Battlefield: Bad Company/Bad Company2)

Try changing the PCV valve. Seems to fix the problem for me most of the time.

What I do:
I just clean the gunk off about once a month. Keep the PCV valve up to date and go from there... The build up on condensation is a pretty common problem with the KJ and it's oil filler neck. Just don't let the oil change shops talk you into a "engine" flush every time you go for an oil change. Those things usually have kerosene in them and eat away at rubber gaskets.


What I think:
The oil filler neck acts like a chimney. As you warm up your engine, some of the hotter air rises to the top of the valve covers. This air is warm enough to rise, it is not hot enough to have evaporated the moisture content contained within. That little chimney that allows a bunch of this semi warm air to get trapped (PCV valve can't evacuate it all). While the air sits there, the ambient temperature and surrounding plastic cools off the air inside the filler neck and then condensation forms. With that ledge design, all the condensation is captured and doesn't fall down into the "hot oil bath" to be thinned back out. Rinse and repeat this heating / cooling effect (if you take a lot of short trips) on a daily basis and you have the build up of milky gunk.


What it does:
I don't know what the long term effects of this really are. I do know that as a side effect of this process, I developed a routine for cleaning and inspecting my engine compartment to help remove the build up. What I have and will continue to wonder is some of the higher mileage members report SOME mechanical problems with valve springs but who's to say this is the direct cause. I really doubt it is, since in most cases a valve spring failure is caused by a stress failure rather than a "moisture induced" problem.... But again, just me speculating here

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02 Liberty Limited
Silver Outside & Taupe Inside
Heated Seats, Sunroof & Infinity speakers
USA Spec I-Pod adaptor, Mopar Sub, Garmin GPS
Tow Package, Select-Trac
Rock Rails, Tow Hooks

sounds pretty dang reasonable to me, sleeve!