Pugs

Hi all, Im new here.I have a question about diagnosing a very slow oil leak on 03 cherokee 4.0 . ive idled the engine for a few minutes and put card board down and no drops, turned off jeep and waited no drops on card board. but a couple days ago when i was out i noticed a drop underneath so when i got home i put card board under again after i turned jeep off, waited 15 mins and there was a small oil drop on board under the bell housing. question is should i be concerned right now? my oil level is fine, also had oil changed about a month and half ago. thank you.

Stabsthedrama

If you're keeping track of your oil loss and there's never much that needs to be added, I wouldn't worry about it yet.

Things you should check/do though that are easy - valve cover gasket (if you're going to do it, get a felpro and try your best to degunk the valve cover and rockers) and oil filter adapter o-ring.
While Idling - get under there and watch your oil filter adapter (where it bolts up to the engine block on your passenger side) like a hawk - see if it starts pooling/dripping. If it needs to get changed look around for the part #'s as they're different with the newer 4.0's and I couldn't tell you what ones you would need. Quick google.

If it's not one of those 2 things, it's your oil pan gasket or rear main seal most likely - and if it's just a very small drip, it's totally not worth fixing at least for awhile.
These 4.0's have the 2 piece RMS's, which is nice because it makes it 100x easier than the 1 piecers since you don't have to pull the trans, but it's still a P.I.T.A.

Pugs

Hey thank you for your quick response. its a very small drip that only appears once in awhile so im gonna just keep an eye on for now till i can get under it and really do some examining.Also the wife and i drove it to the local mall and other places today and didnt notice anything dripping after the engine was turned off immediately , so it cant be that bad so what ever is leaking must be just slowly oozing out.Thank you!

cruiser54

Here ya go.




I'd be looking up ABOVE first, and VERIFYING the source of the oil leak YOURSELF.

Everybody, who doesn't own or have to pay for or perform your vehicle repairs, loves to poke their noggin UNDER the Jeep and come out bearing the false bad news that your RMS is leaking.

Many mechanics, friends, people on Jeep forums who can’t see your Jeep from where they’re at, and good old Uncle Bob seem to enjoy telling you it’s the rear main seal. Has a catastrophic ring to it, doesn’t it?

A simple leak at the back of the valve cover or other source could produce the same symptoms. You don’t need to be a mechanic to figure this out. If you have good eyesight and a dim flashlight, you’re good to go on your own. Don't jump on the RMS/oil pan gasket bandwagon right off the bat.

Almost any oil leak on your 4.0 is gonna drip from the RMS area for two simple reasons.

First off, the engine sits nose-up and any oil will run back to the RMS area. Secondly, the RMS area is also the lowest point on the engine. Simple physics and the old plumber's adage apply here. "$hit flows downhill".

Valve cover gasket, oil pressure sending unit, oil filter adapter seals and distributor gasket, in that order, have to be eliminated as possibilities first.

Revised 02-26-2013

Pugs

Nice info there, I'm gonna check it out on my vacation next week. Also I forgot to mention that my oil pan is dry on the bottom and back side facing bell housing. Thanks for the responses .

cruiser54

You are now well equipped to diagnose your oil leak better than most shops. Enjoy your vacation.

Pugs

Ok, so i crawled under my jeep to look for the leak, running and idled and couldnt see anything, but it is wet under there. i noticed a drop on the tran bell housing ready to fall. I focused my sight on the the oil filter from underneath it seems to be mounted on the block without an adapter, but it is wet on the side under the filter on the block and also on top of the oil pan rim, but not underneath the pan all dry, so now im thinking it might be the oil pan gasket. Thank you, also i called a reliable shop to take a look at it cause its driving me crazy so hopefully by this monday i will know exactly where it is coming from. Oh yeah the filter is tight by the way. Thank you

cruiser54

Excellent job. Is your oil filter mounted perpendicular or parallel to the engine?

Pugs

Thanks for the reply, its perpendicular

cruiser54

Could be a leaking oil filter seal. When was the oil filter last changed?

Pugs

1200 miles ago, lets say around first of November.Ive seen a rear main seal leak before on my old 99 cherokee 4.0 i saw it while idling and the oil pan was wet along with the tran bell housing so im kinda ruling out the rear main seal due to the oil pan being dry on the bottom and back and the drain plug.

cruiser54

Make sure that oil filter is tight, and make sure the oil pressure sending unit isn't leaking due to being whacked during the oil filter removal process 1200 miles ago.

Pugs

Just want to give an update here. I drove 45 mins to a reliable shop after i parked my jeep i didnt notice any drips on the ground, about 10 mins later i looked again and sure enough the jeep had marked its territory.The tech put it on the lift looked all around and then looked under the hood, he said that my rms/oil pan was dry so he looked at my valve cover sure enough that is where the leak was coming from the valve cover. He pointed out the wet areas and explained that it trickled down the engine to the tranny bell housing. He also did a very good job on cleaning things up he said he used brake cleaner and told me i might see some cleaner trickle down and burn off odor. well i drove back home another 45 mins and and turned it off and put card board underneath and went back outside 15 mins later and it was dry so all fixed. Also he used a felpro valve cover gasket he said it came with grommits, i forgot to ask him what the grommits where for im thinking maybe the pcv/ccv valve cause they look clean. Cruiser I thank You !!!! and everbody else that contributed to my oil leak. One more thing the tech is a cherokee owner with 200k miles on his original 4.0 engine. Thank you all

94XjSport94

Wasn't CCV grommets. Grommets are a part of the valve cover change. The CCV grommets are expensive from the dealer.

Congrats.

cruiser54

You're welcome, and congrats!!