my 99 Cherokee sport has milky oil. Just did a oil change a month ago and was fine. No other problems-no lost antifreeze,no oil in coolant, runs great. any idias??

 

where did you find this milky? oil fill cap?

 

How much do you drive? If you're only making short trips the engine never reaches normal operating temperature and condensation will collect in the oil.

 

Isn't that a sign of a blown head gasket?

 

*Has the engine ever been overheated?

*How often do you change your oil?

*What is your ratio of city to highway driving?

*Where did you find the milky substance?

 

X2. But mine smells like Gas. Someone else just said it smelled. I hope thats all it is. If your idling it for long periods of time condesation will buid up and cause that. As someone else said, whats your city/highway driving ratio?

 

hey, thanks for answering. I found the milky oil on the dipstick, it has not overheated and I usually just make short trips with it being I drive a company truck for work. I also live in Rochester,NY where it has been very cold at night and warm during the day-20's to the 50's.
I was told it might be PVC valve? By the way no milky oil on oil fill cap.

 

Short trips that don't heat the oil enough to burn off condensation can do that. Esp. if it's damp and cold outside.
Try taking a good long run once in a while to see if that prevents it.

You have a "CCV" system, not "PCV". They do basically the same thing, scavenge the crankcase for vapor and dispose of it.
There is a hose from the valve cover to the airbox that lets clean air in, another from the valve cover to the intake manifold that sucks crankcase fumes out to burn. There's a metered orifice in the valve cover fitting for this hose that sometimes clogs. If that happens you could see increased oil contamination.
Disconnect the hose where it connects to the air box and put your thumb over it with the motor idling. You should feel a mild vacuum pull there if it's all working right.

 

99% chance it's coolant then, as coolant will not evaporate and condense on the cap. Engine doesn't really have to overheat to crack the cylinder head enough heat/cool cycles will do it too. Rent the cooling system pressure test kit from autozone and pump it up.

 

I have a similar thing going on ..'93 HO, apprantly seller checked compression, he said ok across all 6 .. but who knows in reality .. it does not smoke white .. have not had any coolant loss

bought this jeep 5 months ago .. just did 2nd oil change since noticing weird disptick residues .. have drove it 1500 miles since my 1st oil change after buy

dipstick had some gunk at tip .. changed oil yesterday for 2nd time, slight milk at upper oil mark 2day .. barely .. thought I would step up oil changes to clean out motor

found some milky / dehydrated lookin oil in airbox .. from valve cover tube .. not much

when dumping oil ... looked normal

mainly have been driving it 8 miles (each way) to work & back, highway .. longer runs .. oil looks ok

is there a oil/water separator under valve cover ? as if thats what the air filter crap came from ? .. i plan on pulling the plugs to inspect each cylinder this weekend .. what should I look for? .. besides coolant & decent burn on plugs

just being **** on this motor .. tryin to keep it clean / make it cleaner from day 1

despite this .. I have been slow swapping the auto trans fluid (as recommended on this site) .. up to 7 quarts swapped .. still shifting great, and looks a bit cleaner each 2 quart swap .. old fluid doesnt smell burnt either

 

What you have found in the airbox is a clue as to where you should start. Your CCV system isn't working properly. I would buy both of the CCV (crankcase ventilation) hoses and grommets; not that expensive; around $50 for everything if I remember right, even from the dealership. Then remove the valve cover, clean it thoroughly, install the new grommets, reinstall the valve cover with a fresh gasket, install new CCV hoses and you're done. It is not uncommon for the CCV system to fail over time. Removing the valve cover gives you a good look at your valve train and allows you to thoroughly clean the inlet/outlet for CCV and makes it easy to install the new grommets. Doing the above will restore the systems performance.

Then as you mentioned, I'd reduce the interval for oil changes. The 4.0 is tough; I'd start there!

 

i was just going through this my head was cracked on the bottom and the top but i had the infamous 0331 head if you look down into the oil filler hole in the valve cover most that crack you can see from there. my jeep ran fine but the oil was milky so i pulled the head and ordered a redesigned casting from odessa head came with a 2 yr unlimited mile warranty and only took about 4 hours to change

never mind just looked through the post again and saw that there was no chocolate milk in the upper end sorry but still may be helpful to someone